# Scientific Figure tool pages > Each tool below is a page under https://scientificfigure.com/tools that generates one kind of scientific figure from a written description, and the same tools are available inside one workspace. Pricing and credit costs: https://scientificfigure.com/pricing.md. Capabilities and limits: https://scientificfigure.com/capabilities.md. ## Contents - Tools - [Scientific Figure Tools: Diagram, Poster & Plot Makers](https://scientificfigure.com/tools) - [AI Scientific Illustration Generator — Free Online Tool](https://scientificfigure.com/tools/ai-scientific-illustration-generator) - [Graphical Abstract Maker — AI Generator, Sizes & Templates](https://scientificfigure.com/tools/graphical-abstract-maker) - [Scientific Poster Maker — AI Research Poster Generator](https://scientificfigure.com/tools/scientific-poster-maker) - [Electrical Circuit Diagram Maker — Free Online AI Generator](https://scientificfigure.com/tools/circuit-diagram-maker) - [PRISMA Flow Diagram Generator — AI PRISMA 2020 Maker](https://scientificfigure.com/tools/prisma-flow-diagram-generator) - [Cladogram Maker — Draw a Cladogram Online in Seconds](https://scientificfigure.com/tools/cladogram-maker) - [Phylogenetic Tree Maker — AI Phylogenetic Tree Generator](https://scientificfigure.com/tools/phylogenetic-tree-maker) - [Animal Cell Diagram Generator — Free Labeled Cell Maker](https://scientificfigure.com/tools/animal-cell-diagram) - [Plant Cell Diagram Generator — Free Labeled Cell Maker](https://scientificfigure.com/tools/plant-cell-diagram) - [Cellular Respiration Diagram Generator — Free Pathway Maker](https://scientificfigure.com/tools/cellular-respiration-diagram) - [96-Well Plate Template Maker — Free Plate Map Generator](https://scientificfigure.com/tools/96-well-plate-template) - [6-Well Plate Template Maker — Free Plate Layout Generator](https://scientificfigure.com/tools/6-well-plate-template) - [12-Well Plate Template Maker — Free Plate Layout Generator](https://scientificfigure.com/tools/12-well-plate-template) - [24-Well Plate Template Maker — Free Plate Map Generator](https://scientificfigure.com/tools/24-well-plate-template) - [48-Well Plate Template Maker — Free Plate Map Generator](https://scientificfigure.com/tools/48-well-plate-template) - [384-Well Plate Template Maker — Free Plate Map Generator](https://scientificfigure.com/tools/384-well-plate-template) - [Free Box Plot Maker — AI Box and Whisker Plot Generator](https://scientificfigure.com/tools/box-plot-maker) - [Bar Graph Maker — Free Bar Chart Generator with Error Bars](https://scientificfigure.com/tools/bar-graph-maker) - [Histogram Maker: Free Histogram Generator with Exact Bins](https://scientificfigure.com/tools/histogram-maker) - [Line Graph Maker: Free Line Graph Generator & Creator](https://scientificfigure.com/tools/line-graph-maker) - [Heatmap Generator — Free Heat Map Maker from Excel or CSV](https://scientificfigure.com/tools/heatmap-generator) - [Bode Plotter — Free Bode Plot Generator & Calculator](https://scientificfigure.com/tools/bode-plotter) - [Lewis Structure Generator — Free Lewis Diagram & Dot Maker](https://scientificfigure.com/tools/lewis-structure-generator) - [Tree Diagram Maker & Probability Tree Diagram Generator](https://scientificfigure.com/tools/tree-diagram-maker) - [Radar Chart Maker: Spider Chart Generator from Your Data](https://scientificfigure.com/tools/radar-chart-maker) - [Bell Curve Generator: Normal Distribution Graph Maker](https://scientificfigure.com/tools/bell-curve-generator) - [Scatter Plot Maker with Line of Best Fit, r and R²](https://scientificfigure.com/tools/scatter-plot-maker) - [Coagulation Cascade Diagram — Labeled Clotting Cascade, Free](https://scientificfigure.com/tools/coagulation-cascade-diagram) - [RAAS Diagram — Renin–Angiotensin–Aldosterone System, Free](https://scientificfigure.com/tools/raas-diagram) - [Cell Cycle Diagram — Labeled & Blank, Phases & Checkpoints](https://scientificfigure.com/tools/cell-cycle-diagram) - [Food Web Maker — Labeled & Blank Food Web Diagrams, Free](https://scientificfigure.com/tools/food-web-maker) - [Pedigree Chart Maker — Free Pedigree Diagram Generator](https://scientificfigure.com/tools/pedigree-chart-maker) - [Insulin Signaling Pathway Diagram — Labeled, by Tissue, Free](https://scientificfigure.com/tools/insulin-signaling-pathway) - [PI3K/AKT Signaling Pathway Diagram — Labeled with mTOR, Free](https://scientificfigure.com/tools/pi3k-akt-signaling-pathway) - [DNA Replication Diagram — Labeled Replication Fork Maker](https://scientificfigure.com/tools/dna-replication-diagram) - [Rock Cycle Diagram — Labeled Processes & Simple Drawing](https://scientificfigure.com/tools/rock-cycle-diagram) - [Skeleton Diagram — Labeled Skeletal System, Blank Worksheet](https://scientificfigure.com/tools/skeletal-system-diagram) - [Chloroplast Diagram — Labeled & Blank, Free Maker](https://scientificfigure.com/tools/chloroplast-diagram) - [Meiosis Diagram — Labeled Stages of Meiosis 1 & 2, Free](https://scientificfigure.com/tools/meiosis-diagram) - [Molecular Orbital Diagram Generator: O₂, N₂ & CO MO Diagrams](https://scientificfigure.com/tools/molecular-orbital-diagram-generator) - [Bohr Model Diagram Generator — Bohr–Rutherford Diagram, Free](https://scientificfigure.com/tools/bohr-model-diagram) - [Orbital Diagram Generator: Electron Configuration Diagrams](https://scientificfigure.com/tools/orbital-diagram-generator) - [Nitrogen Cycle Diagram — Labeled & Simple Versions, Free](https://scientificfigure.com/tools/nitrogen-cycle-diagram) - [Neuron Diagram — Labeled Parts & Blank Worksheet, Free](https://scientificfigure.com/tools/neuron-diagram) - [Nephron Diagram — Labeled & Blank, Free Maker](https://scientificfigure.com/tools/nephron-diagram) - [Synapse Diagram — Labeled & Blank, Free Maker](https://scientificfigure.com/tools/synapse-diagram) - [Protein Synthesis Diagram — Transcription & Translation](https://scientificfigure.com/tools/protein-synthesis-diagram) - [Calvin Cycle Diagram — Labeled Light-Independent Reactions](https://scientificfigure.com/tools/calvin-cycle-diagram) - [Free Body Diagram Maker & Drawer — Free FBD Creator](https://scientificfigure.com/tools/free-body-diagram-maker) - [Dichotomous Key Maker — Free Creator & Template](https://scientificfigure.com/tools/dichotomous-key-maker) - [Notch Signaling Pathway Diagram — Labeled, with NICD, Free](https://scientificfigure.com/tools/notch-signaling-pathway) - [TGF-β Signaling Pathway Diagram — Labeled TGF-β/SMAD, Free](https://scientificfigure.com/tools/tgf-beta-signaling-pathway) - [Action Potential Graph — Labeled Diagram, Neuron & Cardiac](https://scientificfigure.com/tools/action-potential-graph) - [Wiggers Diagram Maker — Labeled Cardiac Cycle Diagram](https://scientificfigure.com/tools/wiggers-diagram) - [Brachial Plexus Diagram: Labeled Anatomy and Mnemonic](https://scientificfigure.com/tools/brachial-plexus-diagram) - [Krebs Cycle Diagram — Labeled Citric Acid Cycle Maker](https://scientificfigure.com/tools/krebs-cycle-diagram) - [Carbon Cycle Diagram — Labeled, Simple & Easy to Draw](https://scientificfigure.com/tools/carbon-cycle-diagram) - [Ear Diagram — Labeled & Unlabeled Parts of the Ear](https://scientificfigure.com/tools/ear-diagram) - [Dermatome Map and Dermatome Chart, C2 to S5 Labeled](https://scientificfigure.com/tools/dermatome-map) - Templates and examples - [Free Graphical Abstract Templates — 6 AI-Filled Layouts](https://scientificfigure.com/tools/graphical-abstract-templates) - [Scientific Poster Templates — 6 Styles Filled from Your PDF](https://scientificfigure.com/tools/scientific-poster-templates) - [Research Poster, Graphical Abstract & Illustration Examples](https://scientificfigure.com/examples) - [Graphical Abstract Examples — Journal-Ready Visual Summaries](https://scientificfigure.com/examples/graphical-abstract-examples) - [Scientific & Research Poster Examples with Design Breakdowns](https://scientificfigure.com/examples/scientific-poster-examples) - [Scientific Illustration Examples — 6 Styles Compared](https://scientificfigure.com/examples/scientific-illustration-examples) - Guides - [Visual Abstract Maker — AI Generator for Clinical Papers](https://scientificfigure.com/visual-abstract) ## Tools ### Scientific Figure Tools: Diagram, Poster & Plot Makers URL: https://scientificfigure.com/tools Description: Every Scientific Figure generator on one page: diagram makers, posters, graphical abstracts, illustrations and plots, drawn to journal conventions. --- ### AI Scientific Illustration Generator — Free Online Tool URL: https://scientificfigure.com/tools/ai-scientific-illustration-generator Description: Generate publication-quality scientific illustrations from a text description — botanical plates, anatomical diagrams, ink line art, flat vector. Free online. #### What is a scientific illustration? A scientific illustration is a drawing made to communicate a subject accurately rather than attractively — a botanical plate, an anatomical diagram, a labelled cross-section — where every proportion, structure and label is chosen because it is correct, not because it looks good. That constraint is the whole discipline: an illustration may simplify, but it may not invent. - A scientific illustration can show what a photograph cannot: a cutaway, an idealised specimen, or several developmental stages in one plate. - Simplification is allowed and expected; invention is not. Removing detail is legitimate, adding structures that are not there is not. - ICMJE requires authors to disclose the use of AI-assisted technologies at submission, and chatbots cannot be listed as authors. - Publishers differ sharply on generative imagery — some allow it with disclosure, others prohibit it in figures outright. - Line art destined for print is normally supplied at 600–1200 dpi, higher than the 300 dpi asked of photographs. #### What the generator draws well, and what it does not Stated plainly, so you can tell before spending credits whether your subject is a good fit. - Cell and organelle diagrams — How it does: Reliable | Notes: Anatomy is constrained; there are dedicated plant, animal and respiration tools - Botanical and zoological plates — How it does: Reliable | Notes: Habit, floral parts and dissections in the classic plate conventions - Anatomical diagrams — How it does: Reliable | Notes: Cross-sections and systems at textbook level - Process and mechanism schematics — How it does: Reliable | Notes: Arrows, stages and labelled steps - Lab equipment and apparatus — How it does: Usually good | Notes: Common glassware and instruments; unusual rigs need description - A specific named species — How it does: Varies | Notes: Well-documented species are close; obscure taxa need reference detail from you - Your own unpublished data — How it does: Not suitable | Notes: It draws schematics, not plots — chart your data in a plotting tool - Exact anatomical novelty from your paper — How it does: Not suitable | Notes: It cannot know a structure that has not been described yet Anything the generator has no basis for, it should not be asked to invent. Where a subject is genuinely novel, use the output as a base and correct it on the canvas rather than trusting the first render. #### Three ways to get a scientific figure made Commissioning an illustrator buys judgement and originality; drawing it yourself buys total control at the cost of your time; generating it buys speed. They are not interchangeable, and the right choice depends mostly on how novel your subject is and how many revisions you expect. - Typical turnaround — Commission an illustrator: Days to weeks | Draw it yourself: Hours to days | Generate it: About a minute - Typical cost — Commission an illustrator: Hundreds of currency units per figure | Draw it yourself: Your time | Generate it: A few credits - Revisions — Commission an illustrator: Charged, and scheduled | Draw it yourself: Free but slow | Generate it: Immediate, on the canvas - Subject accuracy — Commission an illustrator: As good as your brief and their research | Draw it yourself: As good as your own knowledge | Generate it: Good on documented subjects, weaker on novel ones - Style consistency across figures — Commission an illustrator: Excellent | Draw it yourself: Depends on your skill | Generate it: Good — the same style applies across a set - Genuinely novel structures — Commission an illustrator: The right choice | Draw it yourself: Workable | Generate it: Needs correction by you - Disclosure obligations — Commission an illustrator: Credit the illustrator | Draw it yourself: None | Generate it: Disclose AI use at submission For a figure that carries a paper’s central claim about something newly described, commissioning is still the safer route. For everything around it — context diagrams, method schematics, teaching figures — generation is usually enough. #### Where are scientific illustrations used? Most figures in a paper are not plots. Schematics, cross-sections and process diagrams carry the context that makes the data readable, and they are usually the ones nobody has time to draw. - Papers and theses: Method schematics, context diagrams and cross-sections for a figure panel, at the resolution the publisher asks for. - Lectures and teaching: Clean plates on white that stay legible when projected and when photocopied in black and white. - Posters and conference talks: Large-format illustrations that hold up at reading distance, in a consistent style across the whole board. - Grant applications and reports: A single explanatory figure that lets a non-specialist reviewer follow the proposal without reading the methods. #### Common questions about scientific illustration **What is a scientific illustration?** A scientific illustration is an accurate, aesthetic depiction of a scientific subject — organisms, anatomy, geology, processes — traditionally drawn by specialist illustrators for textbooks, journals and field guides. **Can AI really produce accurate scientific illustrations?** Modern image models produce impressively accurate and beautiful illustrations from a good description. For publication use, always review scientific details — and use the region redraw tool to fix anything that's off. **Which styles are available?** Nine presets: classic scientific, vintage botanical, medical/anatomical, ink line art, watercolor, flat vector, 2.5D isometric, hand-drawn sketch, and 3D render. Each is tuned with its own prompt so results stay consistent. **Can I use the illustrations in papers and presentations?** Yes — images you generate are yours to use in publications, theses, slides and posters. High-resolution export up to 4K is available depending on the model. **What makes an illustration scientific rather than just a drawing?** Accountability to the subject. Every proportion, structure and label has to be defensible against what is actually known, and where the illustration departs from a real specimen — cutting it open, idealising it, combining stages — the departure must be a recognised convention rather than a convenience. A drawing that looks plausible but shows a structure in the wrong place is not a scientific illustration; it is an error with good lighting. **Can I use AI-generated illustrations in a journal article?** It depends on the publisher, and you must check the specific journal. ICMJE requires authors to disclose the use of AI-assisted technologies at submission, and is explicit that chatbots cannot be listed as authors because they cannot be responsible for the accuracy of the work. Beyond that baseline, policies diverge sharply: some publishers accept generative imagery with disclosure, others prohibit it in figures entirely. Treat the journal’s own guide for authors as the authority. **Do I need to disclose that a figure was AI-generated?** Under the ICMJE recommendations, yes — AI-assisted technologies used in producing submitted work are disclosed at submission, and ICMJE also states that humans remain responsible for any submitted material that involved them. In practice a line in the methods or acknowledgements naming the tool and what it was used for is what journals expect. **What resolution and file format should a scientific figure be?** For print, line art and diagrams are usually supplied at 600–1200 dpi, higher than the 300 dpi normally asked of photographs, because fine strokes and small type alias badly at lower resolutions. TIFF, EPS and PDF are the formats most publishers accept. Check the target journal first — its guide for authors overrides any general rule. **Can it draw a specific named species accurately?** For well-documented species, usually yes — habit, leaf arrangement, floral parts and colouring come out close enough to correct on the canvas. For obscure or recently described taxa, the model has less to work from, and you should supply the distinguishing features in your description rather than assuming they are known. Always check the result against a reference before publishing it. **Can I match my lab’s or journal’s colour scheme?** Yes — name the colours or describe the palette in your prompt, and the illustration is drawn in it. You can also recolour afterwards on the canvas without regenerating, which is the faster route when you already have a figure you are happy with and only the palette needs to change. **Can it produce a figure with several panels?** Yes, though it usually works better to generate each panel separately and assemble them. That way each panel can be corrected on its own, and the labelling (a, b, c) stays under your control rather than being drawn into the image, which matters if a reviewer asks for panels to be reordered. **What is the difference between a scientific illustration and a photograph?** A photograph records one specimen exactly as it was, including the damage, the lighting and whatever was in the way. An illustration shows the subject as it is understood: it can cut the specimen open, remove obscuring structures, idealise an individual into a representative form, or place several developmental stages side by side. Neither is more truthful — they answer different questions, and a paper often needs both. #### Sources - Defining the Role of Authors and Contributors — disclosure of AI-assisted technologies — ICMJE Recommendations: https://www.icmje.org/recommendations/browse/roles-and-responsibilities/defining-the-role-of-authors-and-contributors.html --- ### Graphical Abstract Maker — AI Generator, Sizes & Templates URL: https://scientificfigure.com/tools/graphical-abstract-maker Description: Turn your abstract or paper PDF into a journal-ready graphical abstract in minutes — sized for Elsevier, Cell Press, ACS and MDPI specs. Free to start. #### What a graphical abstract is not A graphical abstract is not a figure lifted from the paper, and it is not an infographic. A figure answers a question for a reader who has already committed; a graphical abstract has to earn that commitment in a few seconds, from a table of contents, against everything else on the page. That is a different brief, and it is why reusing Figure 1 rarely works. - Job — Graphical abstract: Make someone open the paper | Figure from the paper: Present evidence to a reader already reading | Infographic: Explain a topic to a general audience - Where it appears — Graphical abstract: Table of contents, article page, social posts | Figure from the paper: Inside the results section | Infographic: Blogs, press, social media - How long it gets — Graphical abstract: A few seconds | Figure from the paper: Minutes, re-read as needed | Infographic: Under a minute - Number of messages — Graphical abstract: One | Figure from the paper: One per panel, several panels | Infographic: Several, in sequence - Amount of text — Graphical abstract: A handful of short labels | Figure from the paper: Full caption plus axis labels | Infographic: Substantial, often narrative - Data shown — Graphical abstract: Usually simplified or schematic | Figure from the paper: Exact, with error bars and statistics | Infographic: Selected highlights - Peer reviewed — Graphical abstract: Usually not | Figure from the paper: Yes | Infographic: No - Submitted as — Graphical abstract: A separate file | Figure from the paper: Part of the manuscript | Infographic: Not part of submission A schematic in a graphical abstract does not have to carry error bars — it has to be true. Simplifying is allowed; overstating what the data support is not. #### Common questions about graphical abstracts **What size should a graphical abstract be?** It depends on the journal: Elsevier asks for at least 1328 × 531 pixels, Cell Press wants a 1200-pixel square, ACS uses 3.25 × 1.75 inches, and MDPI requires at least 560 × 1100 pixels. Always check your journal's guide for authors. **Do all journals require a graphical abstract?** No. Some journals require one (many Cell Press and MDPI titles), many make it optional, and some don't display them at all. Optional or not, papers with a clear graphical abstract tend to get more visibility in tables of contents and on social media. **How much text should a graphical abstract contain?** As little as possible — short labels, not sentences. A good test: if your graphical abstract still makes sense when scaled to 200 pixels tall, the text amount is right. **What's the difference between a graphical abstract and a visual abstract?** They're largely the same thing — “visual abstract” is more common in medicine and often uses a standardized three-panel layout, while “graphical abstract” is the term publishers like Elsevier and Cell Press use. Both summarize one paper in one image. **What software can I use to make a graphical abstract?** Researchers use Illustrator, PowerPoint, BioRender or dedicated AI tools. Scientific Figure's graphical abstract maker generates a journal-ready draft from a text description of your study, keeps every element editable, and exports at publisher-specific sizes. **Can I use AI to make a graphical abstract for a journal?** Publishers distinguish between general-purpose image generators and dedicated scientific illustration tools. Cell Press, for example, prohibits general-purpose generative AI for graphical abstracts while allowing dedicated tools. Check your target journal's policy, disclose AI assistance where required, and take responsibility for the scientific accuracy of every element. **Is this graphical abstract maker free?** New accounts get free credits at signup, which is enough to make your first graphical abstracts. After that each generation costs credits, and the exact number depends on the model and resolution you choose — it is shown next to the generate button before you spend anything. Failed generations are refunded automatically. **Can I make a graphical abstract online without installing software?** Yes. Everything runs in the browser, including PDF reading, generation and editing. There is nothing to download and no design software to learn, which is the point for researchers who need one figure rather than a design career. **Will it use my actual wording?** Yes. The AI extracts stage labels and the key finding from your text and instructs the image model to render them exactly as written — nothing is invented. Proofread the rendered labels anyway, the way you would proofread any figure before submission. **Is there a graphical abstract template for PowerPoint or Canva?** There are plenty online, and they all leave you with an empty canvas to fill. This tool takes the opposite route: pick one of three visual styles and the AI lays your own content into it. You can still export the result and drop it into a slide deck or a Canva design afterwards. **What if the result isn't quite right?** Every generation lands in your workspace with full editing: quick edits, region redraw, recoloring and version history — the original is always one click away. You can also regenerate with added instructions about what to emphasize or reorder. **How do you make a graphical abstract?** Start from the one sentence you would want a reader to take away, then draw only what that sentence needs. Usually that is three beats laid left to right: what was studied, what was done to it, what changed. Add short labels rather than sentences, keep to two or three colours, and check it at the size the journal actually displays it — around 500 × 200 px for Elsevier. Here, pasting your abstract produces that layout directly. **Can I reuse a figure from my paper as the graphical abstract?** You can, and most journals will accept it, but it usually underperforms. A results figure is built for a reader who has already decided to read the paper: it carries axes, error bars, statistics and a caption that explains it. A graphical abstract has a few seconds and no caption. If you do reuse one, strip it back — remove statistical annotation, enlarge the labels, and add the one-line finding the figure supports. #### Sources - Graphical abstract in Elsevier journals — size, format and font requirements — Elsevier: https://www.elsevier.com/researcher/author/tools-and-resources/graphical-abstract --- ### Scientific Poster Maker — AI Research Poster Generator URL: https://scientificfigure.com/tools/scientific-poster-maker Description: Turn your paper PDF into a conference-ready scientific poster in minutes, not hours in PowerPoint. Six research poster templates, A0 and 48×36. Free to start. #### A poster is not a paper The most common mistake is treating a poster as a compressed manuscript. A paper is read alone for twenty minutes or more; a poster is read standing up, in under two minutes, with the author beside it. That changes the word count, the type size and which element carries the argument — on a poster the figures do, and the text supports them. - Total words — Journal paper: 3,000–8,000 | Conference poster: 300–800 - Time spent reading — Journal paper: 20–60 minutes, seated | Conference poster: Under 2 minutes, standing - Structure — Journal paper: Full IMRaD with full citations | Conference poster: Question, method, key result, takeaway - Role of figures — Journal paper: Support the written argument | Conference poster: Carry the argument; text supports them - Smallest type — Journal paper: 9–11 pt, read at 40 cm | Conference poster: 24 pt minimum, read at 1–2 m - Level of detail — Journal paper: Enough to replicate the work | Conference poster: Enough to start a conversation - References — Journal paper: Complete list | Conference poster: Three to five, or a QR code - Success looks like — Journal paper: Accepted after peer review | Conference poster: Someone stops and asks a question If your poster can be read start to finish without you, it has too much text on it. The gaps are where the conversation happens, and the conversation is the reason poster sessions exist. #### Common questions about scientific posters **What is a scientific poster?** A scientific poster is a large-format visual summary of a research project — a title banner, author block, and condensed introduction, methods, results and conclusion sections arranged around central figures. It's the standard format for presenting work at conference poster sessions. **What is the best way to make a scientific poster?** Traditionally PowerPoint with an academic template, or design tools like Illustrator. The fastest route is an AI poster maker: upload your paper PDF, pick a template, and get a conference-ready draft in about two minutes — then iterate with custom instructions. **Can I make a poster directly from my PDF paper?** Yes — that's the core workflow here. Upload your paper, preprint or extended abstract as a PDF, or simply paste your abstract into the text box, and the AI structures it into a poster. **Is the text on the poster real, or AI gibberish?** Real. A language model first extracts your title, sections and key findings from the source, then the image model is instructed to render exactly that text — spelled as written. **Is there a free scientific poster maker?** You can start free here: new accounts receive free credits at signup — enough to generate your first posters — and failed generations are always refunded automatically. **What size should a scientific poster be?** Check your conference's call for posters first. A0 portrait (841 × 1189 mm) dominates in Europe; 48 × 36 inches landscape is the classic US format. The maker outputs both orientations, and the built-in upscaler prepares them for large-format printing. **Is Canva good for scientific posters?** Canva is a capable general design tool, but its poster templates aren't built around academic conventions — you still assemble IMRaD sections, references and figures by hand. A dedicated scientific poster maker starts from your paper and applies those conventions automatically. **What is the fastest way to make a conference poster?** Upload your paper PDF to an AI poster generator, pick a template, generate — about two minutes to a complete draft. Even with a round or two of regeneration to adjust emphasis, you're done in under fifteen minutes. **Can I edit the poster afterwards?** Yes — every poster opens in your workspace, where you can click to edit text, switch color palettes, upscale for print and export in high resolution. You can also adjust your instructions and regenerate as often as you like. **Which poster template should I choose?** Classic navy for conservative venues; minimal or editorial serif for design-conscious fields; dark or gradient for AI and computational work; life-sciences green for biology and medicine. Browse the template gallery to compare all six. **How much does one poster cost?** 30 credits per poster. New accounts receive free credits at signup, and failed generations are always refunded automatically. **Do you also make graphical abstracts and figures?** Yes — the same pipeline powers a graphical abstract maker and a scientific illustration generator, so your poster, TOC graphic and figures can all come from one place. **How much text should a scientific poster have?** Around 300 to 800 words in total, across the whole poster. That is roughly a tenth of the paper it comes from. Cut by deciding what one sentence you want a reader to leave with, keeping whatever supports it and dropping the rest — background that any attendee at that conference already knows is usually the first thing to go, followed by methods detail that belongs in the paper. **What font size should a scientific poster use?** Never below 24 point for body text, which is the floor Erren and Bourne set in their rules for poster presentation, because a poster is read from one to two metres away rather than at desk distance. In practice: title around 72–100 pt so it carries from three metres, section headings 36–48 pt, body 24–32 pt, and captions no smaller than 18 pt. #### Sources - Ten Simple Rules for a Good Poster Presentation — Erren & Bourne, PLoS Computational Biology 2007 — PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC1876493/ --- ### Electrical Circuit Diagram Maker — Free Online AI Generator URL: https://scientificfigure.com/tools/circuit-diagram-maker Description: Describe a circuit in plain words and get a publication-ready diagram — textbook schematics, realistic breadboard views and blueprint styles. Free online. #### Circuit symbols chart: ANSI and IEC conventions The same component is drawn two ways depending on which standard a textbook follows. Both are correct — pick one per figure and stay consistent. - Resistor — ANSI / IEEE (common in US textbooks): Zigzag line | IEC 60617 (common in Europe): Plain rectangle - Variable resistor — ANSI / IEEE (common in US textbooks): Zigzag with a diagonal arrow through it | IEC 60617 (common in Europe): Rectangle with a diagonal arrow through it - Capacitor — ANSI / IEEE (common in US textbooks): One straight and one curved plate | IEC 60617 (common in Europe): Two straight parallel plates - Inductor — ANSI / IEEE (common in US textbooks): Series of loops | IEC 60617 (common in Europe): Filled or outlined rectangle - Cell — ANSI / IEEE (common in US textbooks): Long plate positive, short plate negative | IEC 60617 (common in Europe): Long plate positive, short plate negative - Lamp — ANSI / IEEE (common in US textbooks): Circle with a cross inside | IEC 60617 (common in Europe): Circle with a cross inside - Switch — ANSI / IEEE (common in US textbooks): Hinged line breaking the wire | IEC 60617 (common in Europe): Hinged line breaking the wire - Fuse — ANSI / IEEE (common in US textbooks): Rectangle with a line through it, or an S-curve | IEC 60617 (common in Europe): Rectangle with a line through it - Earth / ground — ANSI / IEEE (common in US textbooks): Three descending horizontal bars | IEC 60617 (common in Europe): Three descending horizontal bars Only the passive components differ between the two standards. Cells, lamps, switches and ground are drawn the same way in both, which is why a mixed figure often goes unnoticed — and still reads as sloppy to anyone who works in one convention. #### Series vs parallel circuits In a series circuit there is one path, so the current is identical at every point and the supply voltage divides between the components. In a parallel circuit each branch sees the full supply voltage and the branch currents add up to the total. That single difference determines every other contrast below, including what happens when one component fails. - Number of paths — Series circuit: One | Parallel circuit: One per branch - Current — Series circuit: The same at every point | Parallel circuit: Divides between branches, and the branch currents add - Voltage — Series circuit: Divides between components | Parallel circuit: The same across every branch - Total resistance — Series circuit: Sum of the resistances | Parallel circuit: Always smaller than the smallest branch - Adding a component — Series circuit: Raises total resistance, lowers current | Parallel circuit: Lowers total resistance, raises total current - If one component fails open — Series circuit: The whole circuit stops | Parallel circuit: The other branches keep working - Typical use — Series circuit: Switches and fuses in a supply line | Parallel circuit: Household lighting and sockets - Drawn as — Series circuit: One loop, components end to end | Parallel circuit: A ladder, branches between two rails For resistors, the total is R₁ + R₂ + … in series and 1/R = 1/R₁ + 1/R₂ + … in parallel — which is why two equal resistors in parallel give exactly half the resistance of one. #### Where are circuit diagrams used? Circuit diagrams are drawn far more often for teaching and documentation than for manufacture. A schematic that will never be fabricated still has to be correct: the symbols, the polarity and the junction dots carry the meaning whether or not anyone builds the circuit. - Lessons, worksheets and lab reports: Clean schematics for physics lessons, worksheets and lab reports — describe the circuit from the textbook and get a diagram ready to print, with the whiteboard style for a hand-drawn look. - Build guides and electronics tutorials: The breadboard view and the build + schematic pair explain an Arduino or Raspberry Pi hookup at a glance — the exact figure style electronics tutorials and course slides need. - Papers, theses & textbooks: Publication-quality figures with exact labels and consistent typography for methods sections, theses and teaching material — no drawing software or symbol libraries to learn. #### Common questions about circuit diagrams **How does the AI circuit diagram generator work?** You describe the circuit in plain language. The AI first works out the component list — designators, values and the order they connect in — then draws the diagram with standard circuit symbols and your exact labels. If your description is brief, it engineers the standard working version of that circuit for you. **Can it draw a breadboard diagram for Arduino-style projects?** Yes. The Breadboard build style draws the circuit as a realistic pictorial build — battery, jumper wires, resistors with color bands, ICs on the board — and the Build + schematic style pairs that picture with the matching symbol schematic in one figure, which is ideal for tutorials and classroom handouts. **Does it use standard circuit symbols?** The schematic styles use conventional textbook symbols — battery plates, zigzag resistors, diode triangles, switch contacts — with correct polarity on batteries, diodes and electrolytic capacitors, drawn with clean right-angle wiring. **Is this an EDA tool? Can I export a netlist or simulate the circuit?** No — this makes diagram *figures* for teaching, publications, slides and articles, not editable netlists for fabrication. If you need SPICE simulation or PCB layout, use an EDA package; if you need a beautiful, correct-looking diagram in seconds, this is the faster path. **Can I make electrical wiring diagrams or logic circuit diagrams too?** Yes — describe any circuit: household wiring runs, relay logic, logic-gate networks, sensor hookups or power supplies. The AI lays out whatever components you describe; dedicated diagram types for wiring and logic are on the roadmap. **Is the circuit diagram maker free? Can I use the diagrams commercially?** You can generate diagrams on the free plan (with a watermark on exports). Paid plans remove the watermark and unlock every model and high-resolution export, and you can use your diagrams in courses, publications and commercial material. **How do you read a circuit diagram?** Follow the current from one terminal of the supply back to the other, and treat every line as a perfect wire. Junction dots mark where wires connect; lines that cross without a dot do not. Positions on the page mean nothing — the diagram states connection only, so a component drawn near the battery may be physically anywhere. Read component values written beside each symbol, and check the supply polarity before working out direction. **What is the difference between a series and a parallel circuit?** A series circuit has one path, so the same current flows everywhere and the supply voltage divides between components. A parallel circuit has one path per branch, so every branch sees the full supply voltage and the branch currents add. The practical consequence: break one component in a series circuit and everything stops, while in a parallel circuit the other branches keep working. **Why do resistor symbols look different in different textbooks?** Because two standards are both in current use. The zigzag resistor and curved-plate capacitor come from the ANSI/IEEE convention common in US textbooks; the plain rectangle and two straight plates come from IEC 60617, common in Europe and in international standards. Neither is more correct. Ask for whichever convention your course or journal uses and the whole figure is drawn in it. **How do you draw a circuit diagram?** Lay the supply on one side, run the components along the path between its terminals, and keep wires as straight horizontal and vertical lines with right-angle corners. Use a junction dot wherever wires connect and leave crossings undotted. Write values beside their symbols. Here, describing the circuit in a sentence does all of that — including keeping polarity correct on cells, diodes and electrolytic capacitors. **What is the difference between a schematic, a wiring diagram and a pictorial diagram?** A schematic shows how the circuit works: standard symbols, connection only, no physical layout. A wiring diagram shows where the cables actually run between real terminals, which is what you need for installation or fault-finding. A pictorial diagram draws components as they look on a breadboard or a board. All three can describe the same circuit and none substitutes for another. **Can it draw logic circuit symbols?** Yes — AND, OR, NOT, NAND, NOR and XOR gates are drawn in either the distinctive-shape form used in most US textbooks or the rectangular IEC form, along with inputs, outputs and inversion bubbles. Say which convention you want; if you do not, the distinctive-shape form is used, since it is the more widely recognised of the two. **What does the earth or ground symbol mean?** It marks the reference point that all voltages in the circuit are measured against, usually 0 V. Several ground symbols on one diagram do not mean several separate points — they are all the same node, drawn repeatedly so the figure does not fill with long return wires. Chassis ground and earth ground are distinct symbols and are not interchangeable in mains work. #### Sources - IEC 60617 — Graphical symbols for diagrams — International Electrotechnical Commission: https://webstore.iec.ch/en/publication/2723 - Resistors in Series and Parallel — College Physics 2e, section 21.1 — OpenStax: https://openstax.org/books/college-physics-2e/pages/21-1-resistors-in-series-and-parallel --- ### PRISMA Flow Diagram Generator — AI PRISMA 2020 Maker URL: https://scientificfigure.com/tools/prisma-flow-diagram-generator Description: Generate a PRISMA 2020 flow diagram from your screening counts or methods text — official box labels, your numbers reconciled. Ready for papers and theses. #### PRISMA 2020 vs PRISMA 2009 PRISMA 2020 is the current standard and most journals now require it. The visible differences are structural: the 2009 diagram had four phases and a single "records screened" path, while 2020 has three phases, separates database from non-database sources, and reports removals before screening explicitly. A review submitted today with a 2009 diagram will usually be asked to redraw it. - Phases — PRISMA 2009: Identification, Screening, Eligibility, Included | PRISMA 2020: Identification, Screening, Included - Search sources — PRISMA 2009: One combined path | PRISMA 2020: Databases and registers split from other methods - Duplicate removal — PRISMA 2009: Implied in "records screened" | PRISMA 2020: Reported explicitly before screening - Exclusion reasons — PRISMA 2009: At full-text stage | PRISMA 2020: At full-text stage, with counts per reason - Previous review versions — PRISMA 2009: Not covered | PRISMA 2020: Second template covers updates - Term used for the unit — PRISMA 2009: "Articles" used loosely | PRISMA 2020: Records, reports and studies defined separately If your protocol was registered against PRISMA 2009 you may still report against it, but say so in the methods — silently mixing the two structures is what reviewers actually object to. #### Where are PRISMA flow diagrams used? A PRISMA flow diagram is drawn once per review and then revised repeatedly, because screening counts almost always change during peer review. It appears in the methods of systematic reviews, meta-analyses, scoping reviews and theses, and increasingly in the protocol before any screening has happened. - Systematic reviews & meta-analyses: The figure journals expect with checklist item 16a — official labels, your counts, portrait layout ready for the methods section of the paper or the supplement. - Scoping reviews & theses: PRISMA-ScR and student reviews use the same 2020 flow. Paste the numbers from your screening spreadsheet and the diagram is ready for the committee. - Teaching & protocols: The whiteboard and presentation styles explain the selection process in lectures, protocol meetings and journal clubs — same rigor, friendlier look. #### Common questions about PRISMA flow diagrams **What is a PRISMA 2020 flow diagram?** It is the standardized figure defined by the PRISMA 2020 statement that documents study selection in a systematic review: how many records the searches identified, how many were removed before screening, how many were screened, excluded, sought as full texts, assessed for eligibility, and how many studies were finally included. The boxes, their labels and their order come from the official template. **Is a PRISMA flow diagram required for a systematic review?** PRISMA 2020 checklist item 16a asks authors to describe the search and selection results "ideally using a flow diagram", and most journals that require PRISMA compliance treat the diagram as mandatory in practice. Reviewers routinely check that the counts reconcile across the boxes. **Which PRISMA template does the generator use?** The PRISMA 2020 template for new reviews searching databases and registers, which covers the large majority of reviews. If your data mentions websites, organisations or citation searching, the second identification column — "via other methods" — is added automatically. Scoping reviews (PRISMA-ScR) use this same 2020 flow. **What is the difference between records, reports and studies?** A record is one search hit — a title and abstract from a database. A report is the retrieved document itself. A study is the piece of research, which may be described in several reports. The flow counts records through screening, switches to reports at retrieval, and ends with both studies included and reports of those studies. **What if my numbers do not add up?** The generator runs the three reconciliation checks — identified minus removed equals screened, screened minus excluded equals sought, sought minus not retrieved equals assessed — before drawing. A count the arithmetic fully determines is filled in; a genuine mismatch in your numbers is kept verbatim and flagged in the analysis so you can fix the source, not the figure. **Can I edit the diagram after it is generated?** Yes. Every generation opens in the workspace, where Edit in Canvas lets you change any label or count, and the upscaler exports a high-resolution version for submission. Verify the counts against your screening log before you submit — the diagram is a rendering of your numbers, and the numbers are yours. **How do you fill in a PRISMA flow diagram?** Work top to bottom and record every number you actually observed, not the ones that make the arithmetic tidy. Start with records identified per database and per register, then removals before screening, then records screened and excluded, then reports sought and not retrieved, then reports assessed for eligibility with exclusions itemised by reason, and finally studies included. Each stage carries its own count, and the differences between stages must be accounted for. **What is the difference between PRISMA 2020 and PRISMA 2009?** PRISMA 2020 has three phases where 2009 had four, splits database and register searches from other search methods, and reports pre-screening removals explicitly. It also defines records, reports and studies as distinct units. PRISMA 2020 is the current standard and is what most journals now ask for. **Do I need to give a reason for every excluded full text?** Yes. At the eligibility stage the statement requires exclusions to be itemised — each reason with its own count, adding to the total excluded. "Excluded (n = 42)" without reasons is the single most common compliance failure. Reasons are usually short: wrong population, wrong intervention, wrong outcome, wrong study design, no full text available. **Which template should I use if my review is an update?** Use the second official template, the one with columns for studies carried over from the previous version. It reports new records alongside those already included in the earlier review, so a reader can see what the update actually added. Using the new-searches-only template for an update hides that distinction. **Where do records found by hand searching or citation chasing go?** In the right-hand column, under searches via other methods — separate from databases and registers. That separation is one of the main changes PRISMA 2020 introduced, precisely so readers can see how much of the yield came from formal database searching and how much from other routes such as citation chasing, contacting authors, or grey-literature sources. **Is a PRISMA flow diagram needed for a scoping review?** Scoping reviews use PRISMA-ScR, an extension with its own checklist. The flow diagram itself is essentially the same shape, so the diagram you build here works for a scoping review too — but the accompanying checklist you report against should be PRISMA-ScR, not the main PRISMA 2020 checklist. **Can the numbers be corrected after the diagram is drawn?** Yes — the diagram opens in a canvas workspace where any count can be edited directly, and the three arithmetic checks re-run against the corrected figures. That matters in practice because screening counts usually change once or twice during peer review, and redrawing the whole figure by hand each time is where transcription errors get introduced. #### Sources - The PRISMA 2020 statement: an updated guideline for reporting systematic reviews — BMJ 2021;372:n71: https://pmc.ncbi.nlm.nih.gov/articles/PMC8005924/ - PRISMA 2020 flow diagram — PRISMA statement: https://www.prisma-statement.org/prisma-2020-flow-diagram --- ### Cladogram Maker — Draw a Cladogram Online in Seconds URL: https://scientificfigure.com/tools/cladogram-maker Description: Describe a group of organisms and get a ready-to-use cladogram in seconds — teaching ladders, rectangular trees, character matrices. Free online, no drawing. #### Cladogram vs phylogenetic tree A cladogram is one kind of phylogenetic tree — the kind that shows branching order and nothing else. In a phylogram, branch length is proportional to the amount of genetic change; in a chronogram, branch length is time. All three state the same relationships, but only the cladogram makes no claim about how much or how long. Asking whether a diagram is "a cladogram or a phylogenetic tree" is really asking whether its branch lengths mean anything. - Branch length means — Cladogram: Nothing | Phylogram: Amount of genetic change | Chronogram: Elapsed time - Tips line up — Cladogram: Yes, flush at the right | Phylogram: No — they end where their change does | Chronogram: Yes, at the present - Has a time axis — Cladogram: No | Phylogram: No | Chronogram: Yes, in years or millions of years - Built from — Cladogram: Shared derived characters | Phylogram: Sequence data plus a model | Chronogram: Sequences plus fossil calibrations - States branching order — Cladogram: Yes | Phylogram: Yes | Chronogram: Yes - Answers "how different?" — Cladogram: No | Phylogram: Yes | Chronogram: No - Answers "how long ago?" — Cladogram: No | Phylogram: No | Chronogram: Yes A cladogram is never "less accurate" than a phylogram — it makes fewer claims. If your data support branching order but not rates, a cladogram is the honest diagram to draw. #### Where are cladograms used? Almost every cladogram that gets drawn is drawn to explain something, not to publish a new phylogeny. Teaching an evolution unit, illustrating a background section, setting a worksheet — the tree is the argument, and it has to stay readable at whatever size it ends up. - Worksheets, revision notes and lab reports: Worksheets, revision notes and lab reports for evolution units — build the tree from a character table and get the matrix and the diagram in one figure, or a whiteboard version for the lesson itself. - Lectures & science communication: The illustrated style puts an organism at every tip, which is what a slide or an explainer needs — the kind of figure phylogenetics software will not draw and an illustrator has to be commissioned for. - Papers, theses & posters: Clean rectangular trees with exact taxon names and clade labels for a background section, a review or a poster panel, without opening tree-drawing software or preparing a data file. #### Common questions about cladograms **How does the AI cladogram generator work?** You describe the group in plain language. The AI first works out the nested clades — which taxa form each group, and what derived character marks each node — then draws the tree with your exact taxon names at the tips. Give it just a group name and it uses the currently accepted phylogeny; give it a character matrix and it builds the tree that data implies. **Can I build a cladogram from a character table?** Yes, and it is one of the things this does best. Paste the table and pick the Tree + character matrix style: the taxon with the fewest derived characters becomes the outgroup, each character labels the node where it first appears, and the finished figure shows the tree beside the matrix it came from — the exact figure a classroom exercise asks for. **Can it read Newick, or a tree I have already worked out?** Yes. Paste a Newick string or simply write the topology out, and the tree is drawn exactly as specified rather than corrected to the textbook version. If what you asked for conflicts with the accepted phylogeny, the diagram follows your instruction and the note in your workspace says so. **Is this a phylogenetics package? Can I load an alignment or get bootstrap values?** No — this makes tree *figures* for teaching, publications, slides and articles, not phylogenetic inference. If you need to estimate a tree from sequence data with support values, use MEGA, RAxML, IQ-TREE or iTOL; if you need a clean, correct-looking cladogram in about a minute, this is the faster path. **What is the difference between a cladogram and a phylogenetic tree?** Every cladogram is a phylogenetic tree, but it shows branching order alone — its branch lengths are arbitrary. A phylogram scales branch length to the amount of evolutionary change and a chronogram scales it to time. Cladograms are what teaching material and most conceptual figures use, because the relationships are the point. **Is the cladogram maker free? Can I use the diagrams commercially?** You can generate cladograms on the free plan (with a watermark on exports). Paid plans remove the watermark and unlock every model and high-resolution export, and you can use your diagrams in courses, publications and commercial material. **How do you read a cladogram?** Read it at the nodes, not across the page. Two tips are close relatives if the node joining them is near the tips, and distant relatives if you have to travel down to the root to connect them — regardless of how near each other they are printed. Tips are not ranked left to right, and no living tip is more evolved than another: every one has had the same time since the root. **What is a clade?** A clade is one node on the tree plus every descendant of that node, with nothing left out. Birds and crocodiles plus their common ancestor form a clade; "reptiles" as usually meant does not, because it excludes birds while including their ancestor. A group that leaves out some descendants is paraphyletic, and a group assembled from unrelated branches is polyphyletic — neither is a clade. **What is an outgroup and why does a cladogram need one?** The outgroup is a taxon known to lie outside the group you are studying — it is what tells you which character states are ancestral and therefore where the root goes. Without an outgroup a branching pattern has no direction: the same tree could be rooted in several places and would then say quite different things about who is related to whom. **What does a node on a cladogram mean?** A node is the most recent common ancestor of everything above it. It is a hypothesis, not a fossil: it stands for an ancestral population that the character evidence implies existed, and it usually has no name and no specimen attached to it. **What is a synapomorphy?** A synapomorphy is a derived character shared by all members of a clade because it first appeared in their common ancestor — feathers for birds, or a four-chambered heart for birds and crocodiles together. Synapomorphies are the evidence for the grouping; characters that are simply ancestral, or that evolved separately, are not. **How do I make a cladogram from scratch?** Start with a character table: taxa down the side, characters across the top, with the outgroup included. The taxon sharing fewest derived characters with the rest branches off first, and each further derived character marks the next node. Paste that table here and the tree is built from it directly — or describe the group in words and the currently accepted phylogeny is used instead. **Can two cladograms that look different show the same relationships?** Yes, and this is the most common way of misreading them. The branches at any node can be rotated freely, and the same tree may be drawn rectangular, slanted or as a ladder. Two diagrams that look nothing alike can be identical trees — only the nesting of the nodes carries information. #### Sources - Organizing Life on Earth — Biology 2e, section 20.1 — OpenStax: https://openstax.org/books/biology-2e/pages/20-1-organizing-life-on-earth - Determining Evolutionary Relationships — Biology 2e, section 20.2 — OpenStax: https://openstax.org/books/biology-2e/pages/20-2-determining-evolutionary-relationships --- ### Phylogenetic Tree Maker — AI Phylogenetic Tree Generator URL: https://scientificfigure.com/tools/phylogenetic-tree-maker Description: Describe a group of organisms and get a publication-ready phylogenetic tree — branch lengths, bootstrap support, time-calibrated clades. Free online maker. #### Phylogram, chronogram and unrooted tree — telling them apart Look at the scale bar first. If it is labelled in substitutions per site you are reading a phylogram, if it is labelled in years or millions of years you are reading a chronogram, and if there is no scale bar and no root the tree is unrooted and states relationships only. A cladogram is the fourth case: flush tips, no scale bar, branching order alone. - Scale bar reads — Phylogram: Substitutions per site | Chronogram: Years or millions of years | Unrooted tree: Usually substitutions per site - Branch length is — Phylogram: Amount of evolutionary change | Chronogram: Elapsed time | Unrooted tree: Amount of change - Has a root — Phylogram: Yes, from an outgroup | Chronogram: Yes | Unrooted tree: No - Tips line up — Phylogram: No | Chronogram: Yes, at the present | Unrooted tree: No - Can you read divergence dates — Phylogram: No | Chronogram: Yes | Unrooted tree: No - Typical input — Phylogram: Aligned sequences plus a model | Chronogram: Sequences plus fossil calibrations | Unrooted tree: Aligned sequences - Direction of descent shown — Phylogram: Yes | Chronogram: Yes | Unrooted tree: No An unrooted tree is not an unfinished tree. It is the honest output when the data cannot say where the root belongs; adding a root without an outgroup invents a claim the analysis did not make. #### Where are phylogenetic trees used? Most phylogenetic trees in circulation are figures rather than analyses, redrawn from a published topology or from a Newick string some other software produced. What matters at that point is that the root, the nodes, the support values and the outgroup all sit where they belong. - Papers, theses & reviews: Clean phylograms with exact taxon names, support values and a scale bar for a background section, a review or a systematics panel — without preparing a data file or opening tree-drawing software. - Lectures & science communication: Time-calibrated trees and illustrated tips are what a slide or an explainer needs — the kind of figure phylogenetics software will not draw and an illustrator has to be commissioned for. - Evolution units, revision notes and lab reports: Trees for evolution units, revision notes and lab reports: name the group and get a diagram that places roots, nodes, clades and the outgroup correctly, or a whiteboard version for the lesson itself. #### Common questions about phylogenetic trees **How does the AI phylogenetic tree generator work?** You describe the group in plain language. The AI first works out the topology — which taxa form each clade, how far each lineage runs, and what value sits at each node — then draws the tree with your exact taxon names at the tips. Give it just a group name and it uses the currently accepted phylogeny with published branch lengths; give it a tree of your own and it follows that instead. **Can it read Newick format?** Yes. Paste a Newick string and the topology is drawn exactly as written, with its branch lengths and any support values carried through unchanged. If you do not have a file, writing the grouping out in words works just as well — "human and chimp together, then gorilla, then orangutan". **Can I make a time-calibrated tree with divergence times?** Yes — pick the Time-calibrated tree style. Give the ages you want at each node, or simply name the group and the AI uses published divergence estimates. The figure gets a horizontal axis in millions of years with the node ages marked along it, and every tip reaching the present. **Is this a phylogenetics package? Can I load an alignment or compute bootstrap values?** No — this makes tree *figures* for papers, teaching, slides and articles, not phylogenetic inference. If you need to estimate a tree from sequence data, use MEGA, RAxML, IQ-TREE, MrBayes or iTOL. Support values you supply are drawn exactly as given; ones you do not supply are plausible published figures, not a calculation on your data. **What is the difference between a phylogenetic tree and a cladogram?** A cladogram shows branching order alone — its branch lengths are arbitrary. A phylogram scales branch length to the amount of evolutionary change and a chronogram scales it to time. All three are phylogenetic trees, so pick by what you need to say: if only the relationships matter, the cladogram maker draws the simpler figure. **Is the phylogenetic tree maker free? Can I use the trees commercially?** You can generate trees on the free plan (with a watermark on exports). Paid plans remove the watermark and unlock every model and high-resolution export, and you can use your figures in courses, publications and commercial material. **How do you read a phylogenetic tree?** Read relatedness through the nodes, not across the tips. Two taxa are close relatives if the node joining them sits near the tips, and distant relatives if you must travel toward the root to connect them — no matter how near each other they are printed. Then check the scale bar to learn what, if anything, the branch lengths mean, and the node labels to see how well supported each grouping is. **What does the scale bar on a phylogenetic tree mean?** It tells you the unit of branch length, and it is the first thing to look at. A bar labelled something like 0.05 means five substitutions per hundred sites of sequence across that length of branch. A bar labelled in millions of years means the tree is time-calibrated. If the figure has no scale bar, treat the branch lengths as meaningless. **What is an outgroup on a phylogenetic tree?** The outgroup is a taxon known to sit outside the group being studied, included specifically so the tree can be rooted. It identifies which character states are ancestral, which fixes the direction of descent for everything else. Choose one too distant and the rooting becomes unstable; choose one inside the group and the tree is rooted wrongly. **What do bootstrap values mean?** A bootstrap value is the percentage of resampled datasets that recovered that same clade — 95 means the grouping appeared in 95 of 100 replicates. It measures how consistently the data support the grouping, not how old it is and not whether it is true. Values above about 70 are usually reported as reasonable support; low values mark branches worth treating as unresolved. **What is the difference between a node and a clade?** A node is a single branching point: the most recent common ancestor of everything beyond it. A clade is that node plus every one of its descendants. So a node is a point on the tree and a clade is the whole group hanging from it — naming a clade means pointing at a node. **How do I make a phylogenetic tree?** For a figure, describe the group in plain words and the currently accepted phylogeny is drawn, or paste a Newick string from your own analysis and it is rendered as-is. For research, the tree itself comes from sequence data: align the sequences, choose a substitution model, infer the tree with maximum likelihood or Bayesian inference, and bring the resulting Newick here to draw it. **What is the tree of life?** The tree of life is the single phylogeny relating all known organisms, rooted near the split between Bacteria, Archaea and Eukarya. Published versions are always summaries: a complete tree would have millions of tips, so any drawable version collapses whole groups into single branches and shows only the level of detail its figure can carry. #### Sources - Organizing Life on Earth — Biology 2e, section 20.1 — OpenStax: https://openstax.org/books/biology-2e/pages/20-1-organizing-life-on-earth - Determining Evolutionary Relationships — Biology 2e, section 20.2 — OpenStax: https://openstax.org/books/biology-2e/pages/20-2-determining-evolutionary-relationships --- ### Animal Cell Diagram Generator — Free Labeled Cell Maker URL: https://scientificfigure.com/tools/animal-cell-diagram Description: Create a labeled animal cell diagram in seconds — nucleus, mitochondria, ER and Golgi drawn to real proportions, in clean printable textbook style. Free. #### What is an animal cell diagram? An animal cell diagram is a labelled cross-section of a eukaryotic animal cell, showing the nucleus, mitochondria, rough and smooth endoplasmic reticulum, Golgi apparatus, lysosomes and ribosomes held inside a flexible plasma membrane — with no cell wall, no chloroplasts and no large central vacuole. The irregular outline is a cut edge, not a silhouette: the diagram slices the cell open so the organelles inside can be labelled. - The membrane-enclosed compartments of an animal cell together occupy nearly half its volume; the cytosol takes a little more than the other half. - An animal cell has no cell wall, so its outline is drawn as an irregular rounded shape rather than the plant cell’s fixed rectangle. - Animal cells contain a centrosome with a pair of centrioles, which most flowering plant cells lack. - Lysosomes are a standard label on an animal cell diagram; in plant cells the central vacuole does most of the same digestive work. - Animal and plant cells both contain mitochondria — a plant cell has chloroplasts in addition to them, not instead of them. #### Parts of an animal cell and what each one does The twelve labels a complete animal cell diagram carries, and whether a plant cell has the same part. - Plasma membrane — What it does: Encloses the cell and controls what enters and leaves | In plant cells?: Yes - Cytoplasm — What it does: The fluid the organelles sit in — a little over half the cell volume | In plant cells?: Yes - Nucleus — What it does: Holds the DNA and directs protein synthesis | In plant cells?: Yes - Nucleolus — What it does: Region inside the nucleus where ribosomes are assembled | In plant cells?: Yes - Nuclear envelope — What it does: Double membrane whose pores control traffic in and out of the nucleus | In plant cells?: Yes - Rough endoplasmic reticulum — What it does: Ribosome-studded membrane network that folds proteins for export | In plant cells?: Yes - Smooth endoplasmic reticulum — What it does: Makes lipids and stores calcium; carries no ribosomes | In plant cells?: Yes - Golgi apparatus — What it does: Modifies, sorts and packages proteins into vesicles | In plant cells?: Yes - Mitochondria — What it does: Release ATP from glucose by aerobic respiration | In plant cells?: Yes - Ribosomes — What it does: Build proteins from mRNA, free in the cytosol or bound to the rough ER | In plant cells?: Yes - Lysosomes — What it does: Digest worn-out organelles and material taken in from outside | In plant cells?: Rare - Centrosome and centrioles — What it does: Organise the spindle that separates chromosomes during division | In plant cells?: No Ribosomes are the only structure in this list that is not membrane-bound, which is why they are drawn as dots rather than as an outlined compartment. #### Animal cell vs plant cell A plant cell has three structures an animal cell does not: a rigid cellulose cell wall, chloroplasts, and one large central vacuole. An animal cell has two a plant cell usually does not: centrioles and lysosomes. Everything else — nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, ribosomes and cytoplasm — is shared, which is why the two diagrams look more alike than different. - Cell wall — Animal cell: Absent | Plant cell: Present, made of cellulose - Outline in a diagram — Animal cell: Irregular and rounded | Plant cell: Fixed rectangular box - Chloroplasts — Animal cell: Absent | Plant cell: Present in green tissue - Vacuoles — Animal cell: Several small ones, often not drawn | Plant cell: One large central vacuole - Centrioles — Animal cell: Present, inside the centrosome | Plant cell: Absent in most flowering plants - Lysosomes — Animal cell: Present and usually labelled | Plant cell: Rare — the vacuole does the job - Mitochondria — Animal cell: Present | Plant cell: Present - Plasmodesmata — Animal cell: Absent | Plant cell: Present, linking neighbouring cells For a Venn diagram, the overlap holds the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, cytoplasm and plasma membrane; only the eight rows above sit outside it. #### Where are animal cell diagrams used? Most animal cell diagrams are drawn for teaching rather than for research, which is why the label set matters more than the rendering style. - School worksheets and exams: Blank and labelled versions of the same diagram — one to fill in, one to mark against. Both come from the same description. - Lecture slides and handouts: A clean plate on a white background stays readable when projected and when photocopied in black and white. - Lab reports and coursework: A labelled cross-section to sit beside a microscope drawing, using the label vocabulary the course already uses. - Papers, posters and theses: A high-resolution export for a figure panel, where a generic stock illustration would look out of place. #### Common questions about animal cell diagrams **What should a labelled animal cell diagram include?** The standard set: nucleus with nucleolus and nuclear envelope, rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria with cristae, lysosomes, ribosomes, centrosome with centrioles, cytoskeleton, plasma membrane and cytosol. The generator includes and labels all of them by default — tell it if you want a simpler subset. **Can I get an animal cell diagram without labels?** Yes — ask for a blank or unlabelled animal cell diagram and the leader lines and text are left off, leaving the outlines for students to fill in. Generating the labelled version from the same description gives you a matching answer key, drawn identically. **How many parts should the diagram show?** It depends on the level, and asking for fewer parts is usually better than asking for all of them. A middle-school diagram normally labels six: plasma membrane, cytoplasm, nucleus, mitochondria, ribosomes and the endoplasmic reticulum. A senior-school or first-year diagram adds the Golgi apparatus, lysosomes, nucleolus, nuclear envelope, centrioles and the cytoskeleton. **What is the difference between an animal cell and a plant cell diagram?** A plant cell adds a rigid cell wall, chloroplasts and a large central vacuole, and its outline is rectangular; an animal cell has an irregular outline, plus centrioles and lysosomes that plant diagrams usually omit. This tool draws the animal cell — there is a matching plant cell diagram generator for the other. **Do animal cells have mitochondria?** Yes, and so do plant cells. This is the most common misconception about the two diagrams: chloroplasts do not replace mitochondria. A plant cell captures light energy in its chloroplasts and then releases ATP from the resulting sugars in its mitochondria, exactly as an animal cell does. **Do animal cells have a cell wall?** No. An animal cell is bounded only by its plasma membrane, which is flexible — that is why animal cells are drawn with irregular, rounded outlines while plant cells are drawn as boxes. Structural support in animal tissue comes from the cytoskeleton inside and from the extracellular matrix outside, not from a wall. **Do animal cells have vacuoles?** They can, but they are small, temporary and usually left out of the diagram. The single large permanent vacuole that dominates a plant cell diagram has no animal equivalent; what animal cells carry instead are vesicles, which move material between compartments rather than storing it. **What is the difference between rough and smooth ER?** Rough endoplasmic reticulum is studded with ribosomes and folds proteins destined for export or for membranes; smooth endoplasmic reticulum has none, and makes lipids and stores calcium. In a diagram they are drawn as one continuous network — the rough region dotted, the smooth region plain and usually more tubular. **Can I make a Venn diagram of plant and animal cells?** Yes — ask for a plant and animal cell Venn diagram and the shared organelles are placed in the overlap. The overlap holds the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, cytoplasm and plasma membrane; cell wall, chloroplasts, central vacuole and plasmodesmata sit on the plant side, centrioles and lysosomes on the animal side. **How do I draw a simple animal cell diagram?** Ask for a simple animal cell diagram and the render drops to a plain outline with six labels and no cristae, no cytoskeleton and no vesicle detail. Simpler diagrams are not less accurate here — the tool removes structures rather than approximating them, so nothing shown is wrong. **How is this different from a generic AI image tool?** The subject knowledge is built in. Every render is constrained to correct animal cell anatomy — no cell wall or chloroplasts sneaking in — with organelles at measured volume proportions (mitochondria large, nucleus modest) and every label spelled from a fixed vocabulary, so you don’t get garbled pseudo-text. **Can I use the diagrams for school, teaching or publication?** Yes — diagrams you generate are yours to use in worksheets, presentations, handouts, theses and papers. Export high-resolution raster up to 4K depending on the model. **Can I change the labels after generating?** Yes. The result opens in a canvas workspace that recognizes the diagram’s labels — you can edit or translate the text, move leader lines, redraw a region or recolor without regenerating the whole figure. #### Sources - The Compartmentalization of Cells — Molecular Biology of the Cell, 4th edition — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK26907/ - Eukaryotic Cells — Biology 2e, section 4.3 — OpenStax: https://openstax.org/books/biology-2e/pages/4-3-eukaryotic-cells --- ### Plant Cell Diagram Generator — Free Labeled Cell Maker URL: https://scientificfigure.com/tools/plant-cell-diagram Description: Create a labeled plant cell diagram in seconds — cell wall, chloroplasts and central vacuole drawn accurately, in clean printable textbook style. Free. #### What is a plant cell diagram? A plant cell diagram is a labelled cross-section of a plant cell, showing the four structures that make it a plant cell — cell wall, chloroplasts, a large central vacuole and plasmodesmata — alongside the nucleus, mitochondria and membrane organelles it shares with animal cells. The outline you see is a cut edge rather than a silhouette, which is why the wall is drawn as a band with thickness instead of a single stroke. - Four structures animal cells do not have. The cell wall, chloroplasts and other plastids, one large central vacuole, and plasmodesmata crossing the wall into neighbouring cells. - The wall sits outside the membrane. Working outward from the cytosol: plasma membrane, then cell wall, then the middle lamella cementing it to the next cell. Reversing that order is the commonest error in student diagrams. - Plant cells have mitochondria too. Photosynthesis does not replace respiration — a plant cell runs both, so a correct diagram shows chloroplasts and mitochondria together. - The vacuole is the largest compartment. It typically takes over 30% of the cell's volume, and up to 90% in some cell types, pressing the cytoplasm into a thin layer against the wall. - Twelve labels cover most syllabuses. Cell wall, middle lamella, plasma membrane, central vacuole, tonoplast, nucleus with nucleolus, chloroplast, mitochondrion, rough endoplasmic reticulum, Golgi apparatus, ribosomes and plasmodesmata. #### Parts of a plant cell and what each one does The parts a labelled plant cell diagram is normally expected to name, what each one does, and whether an animal cell has it. This is the default label set unless you ask for a shorter one. - Cell wall — What it does: Bears the tension that lets the cell hold turgor pressure, and gives the plant its rigidity | In animal cells?: No - Middle lamella — What it does: Pectin-rich layer cementing the walls of two neighbouring cells together | In animal cells?: No - Plasma membrane — What it does: Controls what enters and leaves; carries the cellulose synthase complexes that spin the wall outward | In animal cells?: Yes - Central vacuole — What it does: Storage, digestion and control of turgor pressure; over 30% of cell volume | In animal cells?: No — small vesicles instead - Tonoplast — What it does: The vacuole membrane; holds the osmotic gradient turgor depends on | In animal cells?: No - Nucleus — What it does: Holds the genome, including about 90% of the genes for chloroplast proteins | In animal cells?: Yes - Chloroplast — What it does: Photosynthesis, plus amino acid and fatty acid synthesis | In animal cells?: No - Mitochondrion — What it does: ATP synthesis by respiration — present alongside chloroplasts, not instead of them | In animal cells?: Yes - Rough endoplasmic reticulum — What it does: Ribosome-studded membrane where secreted and membrane proteins are made | In animal cells?: Yes - Golgi apparatus — What it does: Modifies and sorts proteins, and builds the wall polysaccharides | In animal cells?: Yes - Ribosomes — What it does: Translate mRNA into protein, free in the cytosol or bound to the ER | In animal cells?: Yes - Plasmodesmata — What it does: Cytoplasmic channels through the wall, connecting neighbouring cells | In animal cells?: No — gap junctions instead Syllabuses differ on how many of these they expect. GCSE and middle-school worksheets usually stop at six or seven; A-level, AP and IB add the tonoplast, the plasmodesmata and the ER–Golgi pair. Name the labels you need and only those are drawn. #### Plant cell vs animal cell: what is the difference? Plant cells have four structures animal cells lack — a cell wall, chloroplasts, a large central vacuole and plasmodesmata — and they divide by building a new wall rather than pinching in two. Animal cells have centrioles and prominent lysosomes that higher plant cells do not. Everything else is shared, which is why the two diagrams differ mainly at the outline. - Outer boundary — Plant cell: Cell wall of cellulose and pectin, outside the plasma membrane | Animal cell: Plasma membrane only - Shape — Plant cell: Fixed and angular — usually drawn as a rounded rectangle | Animal cell: Variable — usually drawn round - Chloroplasts — Plant cell: Present, along with other plastids | Animal cell: Absent - Vacuole — Plant cell: One large central vacuole, over 30% of the volume | Animal cell: Several small vesicles and lysosomes - Centrioles — Plant cell: Absent from higher plants | Animal cell: Present, in a centrosome beside the nucleus - Cell junctions — Plant cell: Plasmodesmata through the wall | Animal cell: Gap, tight and anchoring junctions - Cell division — Plant cell: A new wall is built outward from inside the cell | Animal cell: A ring of actin and myosin pinches the cell in two - Shared organelles — Plant cell: Nucleus, mitochondria, ER, Golgi, ribosomes | Animal cell: Nucleus, mitochondria, ER, Golgi, ribosomes Ask for both cells in one figure and they are drawn side by side at matched scale, shared organelles labelled once — the layout a compare-and-contrast question or a Venn diagram exercise expects. One row to check against your syllabus: lysosomes are often listed as animal-only, but plant cells do the same lytic work inside the vacuole, so some textbooks call the vacuole the lysosome equivalent rather than calling lysosomes absent. #### Where are plant cell diagrams used? Plant cell diagrams are used mostly in biology teaching — labelling worksheets, revision sheets and lecture slides — and as the reference plan behind a cell model project. What changes between them is how many parts are labelled, not the anatomy. - School biology: Labelling worksheets and revision sheets from middle school through GCSE, A-level, AP, IB and CBSE class 9. Usually a full labelled plate, or the same drawing with the names removed so students fill them in. - Cell model projects: The reference plan behind a 3D plant cell model in card, clay or cake. A diagram fixes what has to be in the model and where each part sits before anything is built. - Lectures and textbook plates: Undergraduate slides and textbook-style figures, where the wall between two cells is resolved into three layers and the thylakoid stacking inside the chloroplast is drawn rather than implied. - Plant science figures: Schematic panels in work on cell wall composition, chloroplast biology, transport through plasmodesmata and crop traits, with the structure under study marked directly on the cell. #### Common questions about plant cell diagrams **What should a labelled plant cell diagram include?** Twelve parts cover every common syllabus: cell wall, middle lamella, plasma membrane, central vacuole, tonoplast, nucleus with nucleolus, chloroplast, mitochondrion, rough and smooth endoplasmic reticulum, Golgi apparatus, ribosomes and plasmodesmata. All of them are labelled by default — ask for a shorter set if your worksheet only needs six or seven. **Can I get an unlabelled plant cell diagram for students to fill in?** Yes — ask for the blank or numbered version and you get the same drawing with the names removed. Numbered leader lines let you print an answer key alongside it; a fully blank outline works better when students have to place the leader lines themselves. **Can I make a simple plant cell diagram for younger classes?** Yes. Say how many labels you want and the diagram drops to that set. A six-label version usually keeps the cell wall, plasma membrane, nucleus, chloroplast, central vacuole and cytoplasm, and leaves out the ER, Golgi, tonoplast and plasmodesmata. **Can it draw a plant and animal cell comparison in one figure?** Yes — ask for both cells side by side and they are drawn at matched scale, with the shared organelles labelled once. You can also ask for the differences alone, which is the figure a Venn diagram or a compare-and-contrast question expects. **How does the tool keep plant cell anatomy correct?** The subject knowledge is built in. Every render is constrained to correct plant cell anatomy: the wall drawn as a band with thickness rather than a single stroke, the central vacuole taking roughly half the drawn area, no centrioles — and every label spelled from a fixed vocabulary, so you don't get garbled pseudo-text. **Why does the vacuole take up half the diagram?** Because it does in the cell. A mature plant cell's central vacuole typically occupies over 30% of the volume and up to 90% in some cell types, pressing the cytoplasm and organelles into a thin layer at the margin. A diagram with a small vacuole floating mid-cell is drawn from other diagrams, not from cells. **Do plant cells have mitochondria?** Yes — plant cells have both chloroplasts and mitochondria, and a correct diagram shows both. Photosynthesis stores energy as glucose; respiration in the mitochondria releases it as ATP, and it runs day and night. Chloroplasts with no mitochondria is one of the most common errors in student diagrams. **What is the difference between the cell wall and the cell membrane?** The cell wall lies outside the plasma membrane, and it is not a membrane. The wall is an extracellular mesh of cellulose microfibrils in a pectin matrix — freely permeable, and strong enough to bear turgor pressure. The plasma membrane lies against its inner face and is the selective barrier that decides what enters the cell. **How many chloroplasts should a plant cell diagram show?** There is no fixed number — most diagrams draw four to eight, which is a drawing decision rather than a measurement. A leaf mesophyll cell holds far more; a root cell holds none and carries colourless plastids instead. Say which cell type you want and the count follows from it. **Can I match the label list my syllabus uses?** Yes — name the labels and the diagram carries exactly those, in your spelling. That covers British and American variants such as labelled and labeled, and syllabus-specific naming such as cell surface membrane for the plasma membrane. **Can I use a plant cell diagram from here in a worksheet or a thesis?** Yes — the plant cell diagrams you generate are yours to use in biology worksheets, lab handouts, slides and theses. Export goes up to 4K depending on the model. **Can I rename or translate the plant cell labels afterwards?** Yes. The canvas recognizes each label, so you can change 'plasma membrane' to 'cell membrane', translate the set, move a leader line off the vacuole or recolor the chloroplasts without regenerating the figure. #### Sources - The Plant Cell Wall — Molecular Biology of the Cell, 4th edition — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK26928/ - Chloroplasts and Photosynthesis — Molecular Biology of the Cell, 4th edition — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK26819/ - Eukaryotic Cells — Biology 2e, section 4.3 — OpenStax: https://openstax.org/books/biology-2e/pages/4-3-eukaryotic-cells --- ### Cellular Respiration Diagram Generator — Free Pathway Maker URL: https://scientificfigure.com/tools/cellular-respiration-diagram Description: Create a labeled cellular respiration diagram in seconds — glycolysis, Krebs cycle and electron transport chain, with ATP counts at every stage. Free online. #### What is a cellular respiration diagram? A cellular respiration diagram is a labelled figure showing how a cell converts glucose and oxygen into ATP across three stages — glycolysis, the Krebs cycle and the electron transport chain — with each stage placed in the compartment where it actually occurs. Most versions also mark the ATP, NADH and FADH2 produced at each step, so the energy arithmetic can be followed across the whole pathway. - Three stages, three locations. Glycolysis runs in the cytosol; pyruvate oxidation and the Krebs cycle in the mitochondrial matrix; the electron transport chain on the inner mitochondrial membrane. - Overall equation. One glucose plus 6 O2 yields 6 CO2, 6 H2O and roughly 30–32 ATP. - Electron carriers do the work. NADH and FADH2 carry electrons from the first two stages to the chain, where oxygen is the final electron acceptor. - Common variants. An overview plate, a stage-by-stage breakdown, the electron transport chain complex by complex, or respiration paired with photosynthesis. - Typical uses. GCSE, AP, IB and undergraduate biology worksheets, lecture slides, revision handouts and textbook-style figures. #### What is the equation for cellular respiration? The overall equation for cellular respiration is C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy (ATP). One glucose molecule and six oxygen molecules are consumed; six carbon dioxide, six water and roughly 30–32 ATP come out. It is the summary of the whole pathway, not of any single stage. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy (ATP) #### The three stages at a glance Inputs, outputs and ATP yield per molecule of glucose. These are the numbers the generator labels a diagram with unless you ask for a different convention. - Glycolysis — Location: Cytosol | Main inputs: Glucose, 2 ATP, 2 NAD+ | Main outputs: 2 pyruvate, 2 NADH | ATP (net): 2 - Pyruvate oxidation — Location: Mitochondrial matrix | Main inputs: 2 pyruvate, 2 NAD+ | Main outputs: 2 acetyl-CoA, 2 NADH, 2 CO2 | ATP (net): 0 - Krebs cycle — Location: Mitochondrial matrix | Main inputs: 2 acetyl-CoA | Main outputs: 4 CO2, 6 NADH, 2 FADH2 | ATP (net): 2 (as GTP) - Electron transport chain — Location: Inner mitochondrial membrane | Main inputs: 10 NADH, 2 FADH2, 6 O2 | Main outputs: H2O, regenerated NAD+ and FAD | ATP (net): 26–28 - Whole pathway — Location: Cytosol and mitochondrion | Main inputs: 1 glucose + 6 O2 | Main outputs: 6 CO2 + 6 H2O | ATP (net): 30–32 Older textbooks total this as 36–38 ATP. The lower modern figure subtracts the energy spent shuttling cytosolic NADH into the mitochondrion and the proton leak across the inner membrane. Tell the generator which convention your syllabus uses and it labels that one. #### How are photosynthesis and cellular respiration related? Photosynthesis and cellular respiration are opposite reactions: the products of one are the reactants of the other. Photosynthesis stores light energy as glucose and releases oxygen; cellular respiration consumes that glucose and oxygen to release the energy as ATP, returning carbon dioxide and water. - Where — Photosynthesis: Chloroplast | Cellular respiration: Cytosol and mitochondrion - Reactants — Photosynthesis: 6 CO2 + 6 H2O + light | Cellular respiration: C6H12O6 + 6 O2 - Products — Photosynthesis: C6H12O6 + 6 O2 | Cellular respiration: 6 CO2 + 6 H2O + ATP - Energy — Photosynthesis: Stores light energy in chemical bonds | Cellular respiration: Releases stored energy as ATP - When — Photosynthesis: Only in light | Cellular respiration: Continuously, day and night - Which organisms — Photosynthesis: Plants, algae, cyanobacteria | Cellular respiration: Nearly all living cells Plants do both. A common exam mistake is to assume plants only photosynthesise — they respire around the clock in their own mitochondria, and in daylight photosynthesis simply runs faster than respiration, so the plant is a net oxygen producer. #### Where are cellular respiration diagrams used? Cellular respiration diagrams are used mainly in biology teaching — worksheets, revision handouts and lecture slides — and in research figures that need to show where in the pathway an effect happens. What changes between them is the level of detail, not the pathway itself. - School biology: GCSE, A-level, AP and IB worksheets, revision handouts and exam-practice sheets. Usually a full overview plate showing the three stages and their locations, or a single stage blown up for one lesson. - Lectures and textbook plates: Undergraduate slide decks and textbook-style figures, where the electron transport chain is often drawn complex by complex with the proton gradient marked across the inner mitochondrial membrane. - Lab reports and coursework: Respirometry and fermentation practicals need a pathway figure to point at: which step consumes oxygen, where the CO2 being measured is released, why a yeast tube yields ethanol rather than water. - Research figures: Schematic panels in work on mitochondrial disease, cancer metabolism, exercise physiology and drug mechanisms, with the inhibited step or the defective complex marked directly on the pathway. #### Common questions about cellular respiration diagrams **What does a cellular respiration diagram show?** A cellular respiration diagram shows the three stages that turn one glucose molecule into ATP, each drawn in the compartment where it happens. Glycolysis in the cytosol splits glucose into two pyruvate (net 2 ATP, 2 NADH); pyruvate oxidation and the Krebs cycle run in the mitochondrial matrix, releasing CO2 and loading NADH and FADH2; the electron transport chain sits on the inner mitochondrial membrane, where oxygen accepts the electrons and most of the ATP is made by oxidative phosphorylation. **What are the reactants and products of cellular respiration?** The reactants are glucose and oxygen; the products are carbon dioxide, water and ATP. Per glucose molecule that is 1 C6H12O6 and 6 O2 in, and 6 CO2, 6 H2O and roughly 30–32 ATP out. Pyruvate, acetyl-CoA, NADH and FADH2 are intermediates — made and consumed inside the pathway, so they never appear in the overall equation. **Where does each stage of cellular respiration take place?** Glycolysis happens in the cytosol; pyruvate oxidation and the Krebs cycle in the mitochondrial matrix; the electron transport chain in the inner mitochondrial membrane. Misplacing these compartments is the most common error in student-drawn diagrams, so the generator anchors every stage to its location by default. **What is the purpose of cellular respiration?** Cellular respiration converts the chemical energy stored in glucose into ATP, the molecule a cell can actually spend. Glucose cannot power a cell directly, while muscle contraction, active transport, protein synthesis and nerve impulses all run on ATP. Cells store very little ATP at any moment, which is why respiration runs continuously rather than in batches. **How many ATP does cellular respiration produce?** About 30–32 ATP per glucose molecule by current estimates, though many textbooks still teach 36–38. The lower figure accounts for the energy spent shuttling cytosolic NADH into the mitochondrion and for proton leak across the inner membrane. Either convention can be labelled — say which one your course uses. **What is the difference between aerobic and anaerobic respiration?** Aerobic respiration uses oxygen as the final electron acceptor and yields roughly 30–32 ATP per glucose; anaerobic respiration and fermentation do not use oxygen and yield 2. Fermentation stops after glycolysis and regenerates NAD+ by making lactate in muscle or ethanol and CO2 in yeast. You can ask for either pathway, or both on one plate. **Can it show photosynthesis and cellular respiration together?** Yes — ask for the two side by side and the generator draws how each one’s products feed the other. Oxygen and glucose leave the chloroplast; carbon dioxide and water come back from the mitochondrion. There is a starter prompt on this page for exactly that paired figure. **Are the molecule labels accurate?** Yes — labels are drawn from a fixed vocabulary and pinned to the correct compartment, so the diagram is gradeable rather than decorative. The vocabulary covers glucose, pyruvate, acetyl-CoA, NADH, FADH2, ATP, ADP, CO2, O2 and H2O, which is what stops a general image model from producing garbled pseudo-text on the leader lines. **How is this different from a general AI image generator?** The pathway is constrained before anything is drawn — stages, compartments, molecule names and ATP arithmetic are fixed rather than invented. A general image model will happily place the Krebs cycle outside the mitochondrion or coin molecule names that do not exist; this tool cannot, because those elements come from a checked vocabulary instead of free composition. **Is the cellular respiration diagram generator free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. That covers generating and exporting real diagrams before you decide whether to buy credits or subscribe. An account is needed because each diagram is saved to a workspace you can return to and edit. **What file formats can I export?** PNG, JPG and PowerPoint (.pptx) from the workspace, plus SVG when you finish the figure in the canvas editor. Raster export runs up to 4K depending on the model, and an upscaler is available if a draft needs bringing up to print resolution. **Can I change the labels after generating?** Yes — the result opens in a canvas workspace that recognises the diagram’s existing labels. You can rewrite or translate label text, adjust arrows, redraw a single region or recolour, all without regenerating the whole figure. **Can I use the diagrams for school, teaching or publication?** Yes — diagrams you generate are yours to use in worksheets, slides, handouts, theses and published papers, with no separate licence to buy. High-resolution raster export runs up to 4K depending on the model you pick. #### Sources - The Mitochondrion — Molecular Biology of the Cell, 4th edition — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK26894/ - The Mechanism of Oxidative Phosphorylation — The Cell: A Molecular Approach, 2nd edition — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK9885/ --- ### 96-Well Plate Template Maker — Free Plate Map Generator URL: https://scientificfigure.com/tools/96-well-plate-template Description: Create a printable 96-well plate template or color-coded plate map from one line of text — the standard 8×12 grid with A–H and 1–12 headers. Free online. #### What is a 96-well plate template? A 96-well plate template is a figure of the standard microplate grid — 96 circular wells in 8 rows lettered A to H and 12 columns numbered 1 to 12, with well A1 at the top left. Filled with colour-coded groups and a legend it becomes a plate map: the standard way a methods figure, a protocol or a lab notebook records which sample, standard or control each well holds. - A 96-well plate carries its wells in 8 rows lettered A to H and 12 columns numbered 1 to 12, with well A1 at the top left. - ANSI/SLAS 1-2004 fixes the plate footprint at 127.76 × 85.48 mm; the generator draws the plate to this proportion. - Well centres sit 9 mm apart in both directions, so the 12 columns span 99 mm and the 8 rows span 63 mm. - No ANSI/SLAS standard specifies well volume or growth area — a compliant flat-bottom well holds 360 µL at Corning and 400 µL at Thermo Fisher. - A plate map colour-codes wells by experimental group and pairs each colour with a legend entry, which is how the generator renders a described layout. #### 96-well plate dimensions the figure is drawn to Every dimension the ANSI/SLAS microplate standards fix, and the well dimensions they deliberately leave to the manufacturer. - Footprint length — Value: 127.76 mm | Where it is specified: ANSI/SLAS 1-2004 - Footprint width — Value: 85.48 mm | Where it is specified: ANSI/SLAS 1-2004 - Corner radius — Value: 3.18 ± 1.6 mm | Where it is specified: ANSI/SLAS 1-2004 - Plate height, typical — Value: 14.35 ± 0.76 mm | Where it is specified: ANSI/SLAS 2-2004 - Well-to-well pitch — Value: 9 mm in both directions | Where it is specified: ANSI/SLAS 2-2004 - Centre of well A1 — Value: 14.38 mm from the short edge, 11.24 mm from the long edge | Where it is specified: ANSI/SLAS 4-2004 - Well diameter — Value: Not standardized — about 6.8 mm nominal on flat-bottom plates | Where it is specified: Manufacturer - Well volume — Value: Not standardized — 330–400 µL depending on the plate | Where it is specified: Manufacturer - Growth area per well — Value: Not standardized — 0.32–0.34 cm² flat-bottom | Where it is specified: Manufacturer The standards fix the outside of the plate and the positions of the wells; the wells themselves are the manufacturer's. Two equally compliant plates disagree on volume and growth area, so quote those numbers from the datasheet of the plate you actually used, not from a standard. #### 96-well vs 384-well vs 24-well plates All the common microplate formats share one ANSI/SLAS footprint — 127.76 × 85.48 mm — which is why they fit the same readers and robots. What changes between formats is the grid: the well count quadruples and the pitch halves. - Wells — 24-well: 24 | 96-well: 96 | 384-well: 384 - Grid — 24-well: 4 rows × 6 columns | 96-well: 8 rows × 12 columns | 384-well: 16 rows × 24 columns - Row letters — 24-well: A–D | 96-well: A–H | 384-well: A–P - Well pitch — 24-well: About 19.3 mm, by convention | 96-well: 9 mm, per ANSI/SLAS | 384-well: 4.5 mm, per ANSI/SLAS - Typical use — 24-well: Cell culture and imaging | 96-well: ELISA, qPCR and general assays | 384-well: High-throughput screening ANSI/SLAS 2-2004 tabulates the pitch for 96, 384 and 1536 wells — 9, 4.5 and 2.25 mm, each half the one before. The 24- and 48-well pitches are manufacturer convention. The generator draws any of these formats; name the format in the description. #### Where are 96-well plate figures used? A plate figure is drawn either before the experiment, to plan and communicate the layout, or after it, to document what each well held. - Methods figures and papers: A colour-coded plate map with a legend states an assay layout in one panel — clearer than a paragraph listing well ranges, and reviewers can check it at a glance. - Protocols and SOPs: A plate figure in a protocol shows every operator the same layout. Ambiguity about where the standards and controls sit is how plates get transposed. - Lab notebooks and plate planning: Sketch the layout before pipetting: which wells hold standards, which hold samples, which stay empty — then keep the figure as the record. - Teaching and training: A blank template for students to fill in by hand, or a worked ELISA layout for a methods course — both come from a one-line description. #### Common questions about 96-well plates and plate maps **What are the dimensions of a 96-well plate?** ANSI/SLAS 1-2004 fixes the footprint at 127.76 × 85.48 mm with corner radii of 3.18 ± 1.6 mm, and ANSI/SLAS 2-2004 gives a typical plate height of 14.35 ± 0.76 mm. The generator draws the plate outline to this footprint proportion, so the figure matches the object on the bench. **How many rows and columns does a 96-well plate have?** Eight rows lettered A to H and twelve columns numbered 1 to 12, giving 8 × 12 = 96 wells. Well identifiers combine the two, from A1 at the top left to H12 at the bottom right. **Where is well A1 on a 96-well plate?** At the top left. ANSI/SLAS 4-2004 places the centre of A1 at 14.38 mm from the short edge and 11.24 mm from the long edge, and requires the top-left well to be clearly marked. Every figure the generator draws puts A1 top left with the row letters down the left edge. **What is the well spacing on a 96-well plate?** Well centres are 9 mm apart in both directions. ANSI/SLAS 2-2004 tabulates the pitch by format: 9 mm for 96 wells, 4.5 mm for 384 and 2.25 mm for 1536, each half the previous one. The 12 columns therefore span 99 mm and the 8 rows span 63 mm. **How much liquid does a 96-well plate hold?** It depends on the plate, because no ANSI/SLAS standard specifies well volume. Corning lists 360 µL per well for its flat-bottom 3596 and 330 µL for its round-bottom 3788; Thermo Fisher lists 400 µL for the flat-bottom Nunc plate. Recommended working volumes are narrower — 75–200 µL is a common range. **What is the surface area of a 96-well plate well?** Around 0.32 to 0.34 cm² for a flat-bottom well, and the exact figure is the manufacturer's rather than the standard's. Corning gives approximately 0.32 cm²; Greiner Bio-One gives 34 mm². The roughly 6% spread matters whenever a result is normalised per unit of growth area. **What is a plate map?** A plate map is the plate grid with each well colour-coded or labelled by what it holds — sample, standard, control or blank — plus a legend pairing each colour with its group. It is the standard way to record a plate layout in a methods figure, a protocol or a lab notebook, and it is what this tool draws from a described layout. **How should I describe a layout so every well lands correctly?** Name explicit row and column ranges. "Drug A in columns 1–3, Drug B in 4–6, controls in 10–11, blanks in 12" places every group exactly; "three drugs in triplicate" leaves the arithmetic to the model. State the ranges, the group names as you want them spelled in the legend, and which wells stay empty. **Can I make a blank 96-well plate template?** Yes — ask for a blank template and you get the empty 8 × 12 grid with row letters A–H and column numbers 1–12, ready to print and fill in by hand or to annotate in the workspace. Generating a filled version of the same plate later gives you a matching pair. **Can it draw 384-well, 48-well or 24-well plates?** Yes — each format has its own page. The tool keeps every convention and swaps the grid: 24 wells is 4 × 6, 48 is 6 × 8, 96 is 8 × 12 and 384 is 16 × 24 with rows lettered A to P. 6-well and 12-well plates have their own pages too. **Is there an official standard for 96-well plate layout?** The five ANSI/SLAS microplate standards fix the footprint, height, flange, well positions and well-bottom elevation — not what goes in the wells. How you arrange samples, standards and controls is your assay design; the figure's job is to state that arrangement unambiguously, which is what the headers and legend do. **Can I edit the figure after it is generated?** Yes. The figure opens in your workspace, where you can regenerate with a changed layout, recolor a group, edit the legend text on the canvas, add annotations and export the result in high resolution when it is right. #### Sources - ANSI/SLAS Microplate Standards — Society for Laboratory Automation and Screening: https://www.slas.org/education/ansi-slas-microplate-standards/ - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf - ANSI/SLAS 4-2004 (R2012) — Well Positions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_4-2004_WellPositions.pdf --- ### 6-Well Plate Template Maker — Free Plate Layout Generator URL: https://scientificfigure.com/tools/6-well-plate-template Description: Make a printable 6-well plate template or color-coded plate layout from one line of text — the 2×3 grid with rows A–B and columns 1–3. Free to start. #### What is a 6-well plate template? A 6-well plate template is a figure of the 6-well culture plate — 2 rows lettered A and B and 3 columns numbered 1 to 3, with well A1 at the top left. With each well coloured by condition and a legend it becomes a plate layout: the record of what each of the six large wells received. - A 6-well plate has 2 rows lettered A and B and 3 columns numbered 1 to 3. - It is built on the same 127.76 × 85.48 mm ANSI/SLAS footprint as a 96-well plate. - A Corning 6 well is 34.8 mm across with about 9.5 cm² of growth area; Thermo Fisher lists 9.6 cm². - Corning recommends 1.9–2.9 mL of medium per well; Thermo Fisher gives 1–3 mL. #### 6-well plate dimensions, volumes and cell numbers The footprint is standardized; the well figures below are the manufacturers' own, so two sources are given where they differ. - Grid — Value: 2 rows (A–B) × 3 columns (1–3) | Source: Plate convention - Footprint — Value: 127.76 × 85.48 mm | Source: ANSI/SLAS 1-2004 - Well diameter (bottom) — Value: 34.8 mm | Source: Corning CLS-AN-209 - Growth area per well — Value: 9.5 cm² (Corning); 9.6 cm² (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Total well volume — Value: 16.8 mL | Source: Corning CLS-AN-209 - Working volume — Value: 1.9–2.9 mL (Corning); 1–3 mL (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Seeding density — Value: About 0.3 × 10⁶ cells per well | Source: Thermo Fisher - Cells at confluency — Value: About 1.2 × 10⁶ per well | Source: Thermo Fisher - Well pitch — Value: Not standardized — set by the manufacturer | Source: ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells only Cell numbers depend on the cell line — treat the seeding and confluency figures as a starting point, and quote well dimensions from the datasheet of the plate you used. #### 6-well vs 12-well vs 24-well plates The three formats share one footprint. Each step from 6 to 12 to 24 wells roughly halves the growth area per well, trading cells per condition for conditions per plate. - Grid — 6-well: 2 rows × 3 columns | 12-well: 3 rows × 4 columns | 24-well: 4 rows × 6 columns - Row letters — 6-well: A–B | 12-well: A–C | 24-well: A–D - Growth area (Corning) — 6-well: 9.5 cm² | 12-well: 3.8 cm² | 24-well: 1.9 cm² - Working volume (Corning) — 6-well: 1.9–2.9 mL | 12-well: 0.76–1.14 mL | 24-well: 0.38–0.57 mL - Typical use — 6-well: Culture, transfection, colonies | 12-well: Culture, transfection, coverslips | 24-well: Culture, transfection, imaging Growth areas and volumes from Corning application note CLS-AN-209, flat-bottom plates. #### Where are 6-well plate figures used? Six large wells mean enough cells per condition for protein, RNA or colony readouts — and few enough conditions that each well gets its own label. - Transfection and knockdown: Controls and constructs well by well; the layout is what the western blot lanes are later matched against. - Colony formation and scratch assays: Wide wells for clonogenic and wound-healing assays — the figure pairs each well with its treatment next to the result images. - Teaching and lab notebooks: A blank 6-well template prints large enough to write on by hand, and a filled one is a clear record of the day's plating. #### Common questions about 6-well plates **How many rows and columns does a 6-well plate have?** Two rows lettered A and B and three columns numbered 1 to 3 — 2 × 3 = 6 wells. Wells run from A1 at the top left to B3 at the bottom right. **What is the surface area of a 6-well plate well?** About 9.5 cm² by Corning's figure and 9.6 cm² by Thermo Fisher's, with a Corning well 34.8 mm across at the bottom — close to a 35 mm dish. **How much medium goes in a 6-well plate?** Corning recommends 1.9–2.9 mL per well (16.8 mL total well volume); Thermo Fisher gives 1–3 mL of growth medium. 2 mL per well is a common default. **How many cells should I seed in a 6-well plate?** Thermo Fisher's reference figure is about 0.3 × 10⁶ cells per well, reaching about 1.2 × 10⁶ at confluency. Adjust for your cell line's size and doubling time. **What are the dimensions of a 6-well plate?** The same 127.76 × 85.48 mm ANSI/SLAS 1-2004 footprint as a 96-well plate. The well spacing is not in the standard — ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells — and is set by each manufacturer. **When should I use a 6-well plate instead of a 96-well plate?** When each condition needs many cells — protein or RNA extraction, transfection for a western blot, colony formation. Use 96 wells when you need many conditions and a plate-reader readout. **How should I describe a 6-well plate layout?** Name the wells. "Control in A1, reagent only in A2, scrambled siRNA in A3, siRNA #1–#3 in B1–B3" places every condition exactly, each with its own colour and legend entry. **Can it draw other plate formats?** Yes. The 384-, 96-, 48-, 24- and 12-well plates have their own pages, and any page draws another format when you name it in the description. #### Sources - Surface Areas and Recommended Medium Volumes for Corning Cell Culture Vessels (CLS-AN-209) — Corning Life Sciences: https://www.corning.com/catalog/cls/documents/application-notes/CLS-AN-209.pdf - Useful Numbers for Cell Culture — Thermo Fisher Scientific: https://www.thermofisher.com/us/en/home/references/gibco-cell-culture-basics/cell-culture-protocols/cell-culture-useful-numbers.html - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf --- ### 12-Well Plate Template Maker — Free Plate Layout Generator URL: https://scientificfigure.com/tools/12-well-plate-template Description: Make a printable 12-well plate template or color-coded plate layout from one line of text — the 3×4 grid with rows A–C and columns 1–4. Free to start. #### What is a 12-well plate template? A 12-well plate template is a figure of the 12-well culture plate grid — 3 rows lettered A to C and 4 columns numbered 1 to 4, with well A1 at the top left. Coloured by group with a legend it becomes a plate layout recording which treatment or control each well received. - A 12-well plate has 3 rows lettered A to C and 4 columns numbered 1 to 4. - It is built on the same 127.76 × 85.48 mm ANSI/SLAS footprint as a 96-well plate. - A Corning 12 well is 22.1 mm across with about 3.8 cm² of growth area; Thermo Fisher lists 3.5 cm². - Corning recommends 0.76–1.14 mL of medium per well; Thermo Fisher gives 1–2 mL. #### 12-well plate dimensions, volumes and cell numbers The footprint is standardized; the well figures below are the manufacturers' own, so two sources are given where they differ. - Grid — Value: 3 rows (A–C) × 4 columns (1–4) | Source: Plate convention - Footprint — Value: 127.76 × 85.48 mm | Source: ANSI/SLAS 1-2004 - Well diameter (bottom) — Value: 22.1 mm | Source: Corning CLS-AN-209 - Growth area per well — Value: 3.8 cm² (Corning); 3.5 cm² (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Total well volume — Value: 6.9 mL | Source: Corning CLS-AN-209 - Working volume — Value: 0.76–1.14 mL (Corning); 1–2 mL (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Seeding density — Value: About 0.1 × 10⁶ cells per well | Source: Thermo Fisher - Cells at confluency — Value: About 0.5 × 10⁶ per well | Source: Thermo Fisher - Well pitch — Value: Not standardized — set by the manufacturer | Source: ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells only Cell numbers depend on the cell line — treat the seeding and confluency figures as a starting point, and quote well dimensions from the datasheet of the plate you used. #### 12-well vs 6-well vs 24-well plates The three formats share one footprint. Each step from 6 to 12 to 24 wells roughly halves the growth area per well, trading cells per condition for conditions per plate. - Grid — 6-well: 2 rows × 3 columns | 12-well: 3 rows × 4 columns | 24-well: 4 rows × 6 columns - Row letters — 6-well: A–B | 12-well: A–C | 24-well: A–D - Growth area (Corning) — 6-well: 9.5 cm² | 12-well: 3.8 cm² | 24-well: 1.9 cm² - Working volume (Corning) — 6-well: 1.9–2.9 mL | 12-well: 0.76–1.14 mL | 24-well: 0.38–0.57 mL - Typical use — 6-well: Culture, transfection, colonies | 12-well: Culture, transfection, coverslips | 24-well: Culture, transfection, imaging Growth areas and volumes from Corning application note CLS-AN-209, flat-bottom plates. #### Where are 12-well plate figures used? A 12-well plate suits small treatment sets with triplicates, and the layout figure keeps the treatments and replicates straight. - Treatments in triplicate: Four conditions down the columns, three replicates down the rows — the classic 12-well design, readable in one small figure. - Coverslip imaging and differentiation: Wide wells take coverslips or longer cultures; the layout records which well carries which stain or time point. - Lab notebooks and protocols: Print a blank template to fill in at the bench, or keep a filled plate layout as the record of what went where. #### Common questions about 12-well plates **How many rows and columns does a 12-well plate have?** Three rows lettered A to C and four columns numbered 1 to 4 — 3 × 4 = 12 wells. Wells run from A1 at the top left to C4 at the bottom right. **What is the surface area of a 12-well plate well?** About 3.8 cm² by Corning's figure and 3.5 cm² by Thermo Fisher's, with a Corning well 22.1 mm across at the bottom. Use your plate's datasheet whenever results are normalised per area. **How much medium goes in a 12-well plate?** Corning recommends 0.76–1.14 mL per well (6.9 mL total well volume); Thermo Fisher gives 1–2 mL of growth medium. **How many cells should I seed in a 12-well plate?** Thermo Fisher's reference figure is about 0.1 × 10⁶ cells per well, reaching about 0.5 × 10⁶ at confluency. Adjust for your cell line's size and doubling time. **What are the dimensions of a 12-well plate?** The same 127.76 × 85.48 mm ANSI/SLAS 1-2004 footprint as a 96-well plate. The well spacing is not in the standard — ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells — and is set by each manufacturer. **How should I describe a 12-well plate layout?** Name the columns, rows or single wells. "Vehicle in column 1, 1 µM in column 2, 5 µM in column 3, 10 µM in column 4, rows A–C as triplicates" places every group exactly. **Can I make a blank 12-well plate template?** Yes — ask for a blank template and you get the empty 3 × 4 grid with rows A–C and columns 1–4, ready to print and fill in by hand. **Can it draw other plate formats?** Yes. The 384-, 96-, 48-, 24- and 6-well plates have their own pages, and any page draws another format when you name it in the description. #### Sources - Surface Areas and Recommended Medium Volumes for Corning Cell Culture Vessels (CLS-AN-209) — Corning Life Sciences: https://www.corning.com/catalog/cls/documents/application-notes/CLS-AN-209.pdf - Useful Numbers for Cell Culture — Thermo Fisher Scientific: https://www.thermofisher.com/us/en/home/references/gibco-cell-culture-basics/cell-culture-protocols/cell-culture-useful-numbers.html - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf --- ### 24-Well Plate Template Maker — Free Plate Map Generator URL: https://scientificfigure.com/tools/24-well-plate-template Description: Make a printable 24-well plate template or color-coded plate map from one line of text — the 4×6 grid with rows A–D and columns 1–6. Free to start. #### What is a 24-well plate template? A 24-well plate template is a figure of the 24-well culture plate grid — 4 rows lettered A to D and 6 columns numbered 1 to 6, with well A1 at the top left. Coloured by group with a legend it becomes a plate map: a record of which construct, treatment or control each well received. - A 24-well plate has 4 rows lettered A to D and 6 columns numbered 1 to 6. - It is built on the same 127.76 × 85.48 mm ANSI/SLAS footprint as a 96-well plate. - A Corning 24 well is 15.6 mm across with 1.9 cm² of growth area — the figure Thermo Fisher gives too. - Corning recommends 0.38–0.57 mL of medium per well; Thermo Fisher gives 0.5–1.0 mL. #### 24-well plate dimensions, volumes and cell numbers The footprint is standardized; the well figures below are the manufacturers' own, so two sources are given where they differ. - Grid — Value: 4 rows (A–D) × 6 columns (1–6) | Source: Plate convention - Footprint — Value: 127.76 × 85.48 mm | Source: ANSI/SLAS 1-2004 - Well diameter (bottom) — Value: 15.6 mm | Source: Corning CLS-AN-209 - Growth area per well — Value: 1.9 cm² | Source: Corning CLS-AN-209; Thermo Fisher - Total well volume — Value: 3.4 mL | Source: Corning CLS-AN-209 - Working volume — Value: 0.38–0.57 mL (Corning); 0.5–1.0 mL (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Seeding density — Value: About 0.05 × 10⁶ cells per well | Source: Thermo Fisher - Cells at confluency — Value: About 0.24 × 10⁶ per well | Source: Thermo Fisher - Well pitch — Value: Not standardized — set by the manufacturer | Source: ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells only Cell numbers depend on the cell line — treat the seeding and confluency figures as a starting point, and quote well dimensions from the datasheet of the plate you used. #### 24-well vs 12-well vs 48-well plates The three formats share one footprint. Each step from 12 to 24 to 48 wells roughly halves the growth area per well, trading cells per condition for conditions per plate. - Grid — 12-well: 3 rows × 4 columns | 24-well: 4 rows × 6 columns | 48-well: 6 rows × 8 columns - Row letters — 12-well: A–C | 24-well: A–D | 48-well: A–F - Growth area (Corning) — 12-well: 3.8 cm² | 24-well: 1.9 cm² | 48-well: 0.95 cm² - Working volume (Corning) — 12-well: 0.76–1.14 mL | 24-well: 0.38–0.57 mL | 48-well: 0.19–0.285 mL - Typical use — 12-well: Culture, transfection, coverslips | 24-well: Culture, transfection, imaging | 48-well: Culture, small treatment screens Growth areas and volumes from Corning application note CLS-AN-209, flat-bottom plates. #### Where are 24-well plate figures used? A 24-well plate holds enough cells per well for western blots, qPCR or imaging, and its map records which well got which treatment. - Transfection and knockdown experiments: Controls, empty vector and constructs in columns, replicates down the rows — the map is the record you check lysates against. - Imaging on coverslips: Wells hold coverslips for immunofluorescence; the map ties each coverslip to its condition before it is mounted. - Methods figures and protocols: A colour-coded plate figure states the layout in one panel, for reviewers and for every operator repeating the experiment. #### Common questions about 24-well plates **How many rows and columns does a 24-well plate have?** Four rows lettered A to D and six columns numbered 1 to 6 — 4 × 6 = 24 wells. Wells run from A1 at the top left to D6 at the bottom right. **What is the surface area of a 24-well plate well?** About 1.9 cm², the figure both Corning and Thermo Fisher give, with a Corning well 15.6 mm across at the bottom. **How much medium goes in a 24-well plate?** Corning recommends 0.38–0.57 mL per well (3.4 mL total well volume); Thermo Fisher gives 0.5–1.0 mL of growth medium. Use the lower end for transfection mixes and the upper end for longer incubations. **How many cells should I seed in a 24-well plate?** Thermo Fisher's reference figure is about 0.05 × 10⁶ cells per well, reaching about 0.24 × 10⁶ at confluency. Adjust for your cell line's size and doubling time. **What are the dimensions of a 24-well plate?** The same 127.76 × 85.48 mm ANSI/SLAS 1-2004 footprint as a 96-well plate. The well spacing is not in the standard — ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells — and is set by each manufacturer. **When should I use a 24-well plate instead of a 96-well plate?** When each condition needs more cells than a 96 well holds — protein or RNA extraction, transfection, imaging on coverslips. Use 96 wells when you need many conditions and a plate-reader readout. **Can I make a blank 24-well plate template or plate map?** Yes — ask for a blank template and you get the empty 4 × 6 grid with rows A–D and columns 1–6; describe the groups by column or well ("construct A in columns 3–4") and you get the coloured plate map with a legend. **Can it draw other plate formats?** Yes. The 384-, 96-, 48-, 12- and 6-well plates have their own pages, and any page draws another format when you name it in the description. #### Sources - Surface Areas and Recommended Medium Volumes for Corning Cell Culture Vessels (CLS-AN-209) — Corning Life Sciences: https://www.corning.com/catalog/cls/documents/application-notes/CLS-AN-209.pdf - Useful Numbers for Cell Culture — Thermo Fisher Scientific: https://www.thermofisher.com/us/en/home/references/gibco-cell-culture-basics/cell-culture-protocols/cell-culture-useful-numbers.html - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf --- ### 48-Well Plate Template Maker — Free Plate Map Generator URL: https://scientificfigure.com/tools/48-well-plate-template Description: Make a printable 48-well plate template or color-coded plate map from one line of text — the 6×8 grid with rows A–F and columns 1–8. Free to start. #### What is a 48-well plate template? A 48-well plate template is a figure of the 48-well culture plate grid — 6 rows lettered A to F and 8 columns numbered 1 to 8, with well A1 at the top left. Coloured by group with a legend it becomes a plate map that records which treatment, dose or control each well holds. - A 48-well plate has 6 rows lettered A to F and 8 columns numbered 1 to 8. - It is built on the same 127.76 × 85.48 mm ANSI/SLAS footprint as a 96-well plate, so it fits the same plate readers. - A Corning 48 well is 11.0 mm across with about 0.95 cm² of growth area; Thermo Fisher lists 1.1 cm². - Corning recommends 0.19–0.285 mL of medium per well; Thermo Fisher gives 0.2–0.4 mL. #### 48-well plate dimensions, volumes and cell numbers The footprint is standardized; the well figures below are the manufacturers' own, so two sources are given where they differ. - Grid — Value: 6 rows (A–F) × 8 columns (1–8) | Source: Plate convention - Footprint — Value: 127.76 × 85.48 mm | Source: ANSI/SLAS 1-2004 - Well diameter (bottom) — Value: 11.0 mm | Source: Corning CLS-AN-209 - Growth area per well — Value: 0.95 cm² (Corning); 1.1 cm² (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Total well volume — Value: 1.6 mL | Source: Corning CLS-AN-209 - Working volume — Value: 0.19–0.285 mL (Corning); 0.2–0.4 mL (Thermo Fisher) | Source: Corning CLS-AN-209; Thermo Fisher - Seeding density — Value: About 0.03 × 10⁶ cells per well | Source: Thermo Fisher - Cells at confluency — Value: About 0.12 × 10⁶ per well | Source: Thermo Fisher - Well pitch — Value: Not standardized — set by the manufacturer | Source: ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells only Cell numbers depend on the cell line — treat the seeding and confluency figures as a starting point, and quote well dimensions from the datasheet of the plate you used. #### 48-well vs 24-well vs 96-well plates The three formats share one footprint. Going from 24 to 48 to 96 wells roughly halves the growth area per well each step, trading cells per condition for conditions per plate. - Grid — 24-well: 4 rows × 6 columns | 48-well: 6 rows × 8 columns | 96-well: 8 rows × 12 columns - Row letters — 24-well: A–D | 48-well: A–F | 96-well: A–H - Growth area (Corning) — 24-well: 1.9 cm² | 48-well: 0.95 cm² | 96-well: 0.32 cm² - Working volume (Corning) — 24-well: 0.38–0.57 mL | 48-well: 0.19–0.285 mL | 96-well: 100–200 µL - Typical use — 24-well: Culture, transfection, imaging | 48-well: Culture, small treatment screens | 96-well: ELISA, qPCR, assays Growth areas and volumes from Corning application note CLS-AN-209, flat-bottom plates. #### Where are 48-well plate figures used? A 48-well plate is the step between culture plates and assay plates, and its map usually records a treatment series. - Dose–response and toxicity series: Eight columns take a vehicle, a blank and six concentrations; six rows are the replicates — one map shows the whole design. - Protocols and SOPs: A plate figure in a protocol gives every operator the same layout, which is how transposed rows and swapped doses are avoided. - Methods figures: A colour-coded map with a legend states the layout in one panel, clearer than a paragraph of well ranges. #### Common questions about 48-well plates **How many rows and columns does a 48-well plate have?** Six rows lettered A to F and eight columns numbered 1 to 8 — 6 × 8 = 48 wells. Wells run from A1 at the top left to F8 at the bottom right. **What is the surface area of a 48-well plate well?** About 0.95 cm² by Corning's figure and 1.1 cm² by Thermo Fisher's, with a Corning well 11.0 mm across at the bottom. The difference matters whenever results are normalised per unit of growth area, so use your plate's datasheet. **How much medium goes in a 48-well plate?** Corning recommends 0.19–0.285 mL per well (1.6 mL total well volume); Thermo Fisher gives 0.2–0.4 mL of growth medium. **How many cells should I seed in a 48-well plate?** Thermo Fisher's reference figure is about 0.03 × 10⁶ cells per well, reaching about 0.12 × 10⁶ at confluency. Adjust for your cell line's size and doubling time. **What are the dimensions of a 48-well plate?** The same 127.76 × 85.48 mm ANSI/SLAS 1-2004 footprint as a 96-well plate, so it fits the same readers and holders. The well spacing is not in the standard — ANSI/SLAS 4-2004 covers 96, 384 and 1536 wells — and is set by each manufacturer. **How should I describe a 48-well layout?** Give explicit ranges. "Blanks in column 1, vehicle in column 2, 0.1–30 µM in columns 3–8, rows A–F as replicates" places every group exactly; a count such as "six doses in sextuplicate" leaves the arithmetic to the model. **Can I make a blank 48-well plate template?** Yes — ask for a blank template and you get the empty 6 × 8 grid with rows A–F and columns 1–8, ready to print or annotate in the workspace. **Can it draw other plate formats?** Yes. The 384-, 96-, 24-, 12- and 6-well plates have their own pages, and any page draws another format when you name it in the description. #### Sources - Surface Areas and Recommended Medium Volumes for Corning Cell Culture Vessels (CLS-AN-209) — Corning Life Sciences: https://www.corning.com/catalog/cls/documents/application-notes/CLS-AN-209.pdf - Useful Numbers for Cell Culture — Thermo Fisher Scientific: https://www.thermofisher.com/us/en/home/references/gibco-cell-culture-basics/cell-culture-protocols/cell-culture-useful-numbers.html - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf --- ### 384-Well Plate Template Maker — Free Plate Map Generator URL: https://scientificfigure.com/tools/384-well-plate-template Description: Make a printable 384-well plate template or color-coded plate layout from one line of text — the 16×24 grid with rows A–P and columns 1–24. Free online. #### What is a 384-well plate template? A 384-well plate template is a figure of the high-density microplate grid — 384 wells in 16 rows lettered A to P and 24 columns numbered 1 to 24, with well A1 at the top left. Coloured by group with a legend it becomes a plate map, the way a screening protocol, a qPCR run sheet or a methods figure records what each well holds. - A 384-well plate has 16 rows lettered A to P and 24 columns numbered 1 to 24 — the layout ANSI/SLAS 4-2004 specifies. - It shares the 127.76 × 85.48 mm ANSI/SLAS 1-2004 footprint of a 96-well plate, with the well pitch halved to 4.5 mm. - A standard Corning 384 well is square, 2.7 × 2.7 mm, holding 112 µL in total with a 25–50 µL working volume. - One 384-well plate holds the wells of four 96-well plates, which is why screening moves to it. #### 384-well plate dimensions and volumes What the ANSI/SLAS standards fix for a 384-well plate, and the well size and volumes they leave to the manufacturer. - Grid — Value: 16 rows (A–P) × 24 columns (1–24) | Where it is specified: ANSI/SLAS 4-2004 - Footprint — Value: 127.76 × 85.48 mm | Where it is specified: ANSI/SLAS 1-2004 - Well-to-well pitch — Value: 4.5 mm in both directions | Where it is specified: ANSI/SLAS 4-2004 - Centre of well A1 — Value: 12.13 mm from the left edge, 8.99 mm from the top edge | Where it is specified: ANSI/SLAS 4-2004 - Well size, standard — Value: 2.7 × 2.7 mm, square | Where it is specified: Corning CLS-AN-209 - Total well volume — Value: 112 µL (low-volume plates: 50 µL) | Where it is specified: Corning CLS-AN-209 - Working volume — Value: 25–50 µL (low-volume plates: 5–40 µL) | Where it is specified: Corning CLS-AN-209 - Growth area per well — Value: 0.056 cm² | Where it is specified: Corning CLS-AN-209 The standards fix the plate and the well positions; well shape and volume are the manufacturer's. Quote volumes from the datasheet of the plate you used — a low-volume 384 plate holds less than half of a standard one. #### 384-well vs 96-well plates Both formats share one footprint, so they fit the same readers and robots. The 384-well plate puts four times the wells in that space by halving the pitch. - Grid — 96-well: 8 rows × 12 columns | 384-well: 16 rows × 24 columns - Row letters — 96-well: A–H | 384-well: A–P - Well pitch — 96-well: 9 mm | 384-well: 4.5 mm - Working volume (Corning) — 96-well: 100–200 µL | 384-well: 25–50 µL - Typical use — 96-well: ELISA, qPCR, general assays | 384-well: High-throughput screening, qPCR Moving a 96-well assay to 384 wells cuts reagent use per well about fourfold but asks for more precise pipetting — most labs fill 384-well plates with a liquid handler or a 16-channel pipette. #### Where are 384-well plate figures used? At 384 wells a layout is too dense to describe in prose — a plate map is how the design is agreed, run and reported. - Screening campaigns: Control columns at the edges, compounds in the middle: the map shows where every control sits, which is what the Z′-factor and hit calls are computed from. - qPCR run sheets: Samples, standards and no-template controls across 384 wells — a coloured map checked against the instrument's plate setup before the run catches transposed rows. - Methods figures: One panel states the full plate design, with the row and column ranges readable at a glance by reviewers. #### Common questions about 384-well plates **How many rows and columns does a 384-well plate have?** Sixteen rows lettered A to P and twenty-four columns numbered 1 to 24 — 16 × 24 = 384 wells. Well names run from A1 at the top left to P24 at the bottom right, the layout ANSI/SLAS 4-2004 specifies. **What is the well spacing on a 384-well plate?** 4.5 mm centre to centre in both directions, half the 9 mm of a 96-well plate. ANSI/SLAS 4-2004 puts the centre of A1 12.13 mm from the left edge and 8.99 mm from the top edge; the 24 columns span 103.5 mm and the 16 rows 67.5 mm. **How much liquid does a 384-well plate hold?** A standard Corning 384 well holds 112 µL in total, with a recommended working volume of 25–50 µL. Low-volume 384 plates hold 50 µL with a 5–40 µL working range. No ANSI/SLAS standard fixes well volume, so take the figure from your plate's datasheet. **How does a 384-well plate relate to four 96-well plates?** Because the pitch is exactly half, each 96-well position maps onto a 2 × 2 block of 384 wells. Four 96-well plates can be interleaved into one 384-well plate, one per quadrant offset (A1, A2, B1, B2) — worth showing in the map when samples come from 96-well source plates. **When should I use a 384-well plate instead of a 96-well plate?** When the number of conditions or the reagent cost matters more than volume per well — compound screens, dose–response panels and large qPCR runs. Stay with 96 wells for manual pipetting, assays that need 100 µL or more, or when cells must be harvested per well. **How should I describe a 384-well layout so every well lands correctly?** Give explicit row and column ranges. "Negative controls in columns 1–2, positive controls in 23–24, compounds in 3–22" or "cell line A in rows A–H, cell line B in rows I–P" places every group exactly; "40 compounds in duplicate" leaves the arithmetic to the model. **Can I make a blank 384-well plate template?** Yes — ask for a blank template and you get the empty 16 × 24 grid with rows A–P and columns 1–24, ready to print and fill in by hand or to annotate in the workspace. **Can it draw other plate formats?** Yes. The 96-, 48-, 24-, 12- and 6-well plates have their own pages, and any page draws another format when you name it in the description. #### Sources - ANSI/SLAS 4-2004 (R2012) — Well Positions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_4-2004_WellPositions.pdf - ANSI/SLAS 1-2004 (R2012) — Footprint Dimensions for Microplates — Society for Laboratory Automation and Screening: https://www.slas.org/SLAS/assets/File/public/standards/ANSI_SLAS_1-2004_FootprintDimensions.pdf - Surface Areas and Recommended Medium Volumes for Corning Cell Culture Vessels (CLS-AN-209) — Corning Life Sciences: https://www.corning.com/catalog/cls/documents/application-notes/CLS-AN-209.pdf --- ### Free Box Plot Maker — AI Box and Whisker Plot Generator URL: https://scientificfigure.com/tools/box-plot-maker Description: Free boxplot maker: paste data or upload CSV/Excel for exact quartiles, medians and outliers, drawn as a publication-ready box plot in journal styles. #### What is a box plot? A box plot (box and whisker plot) summarizes a numeric dataset with five values: the minimum, first quartile, median, third quartile and maximum. The box spans the middle half of the data from Q1 to Q3, the line inside it marks the median, the whiskers reach the most extreme points within 1.5 × IQR of the box, and anything beyond them is drawn as an individual outlier point. - Paste values straight into the prompt or attach up to three CSV, TSV or Excel files — one column per group, or label/value rows. - Quartiles, medians, whiskers and outliers are computed exactly — linear-interpolation quartiles with Tukey 1.5 × IQR fences — before the AI draws a single line. - Journal style presets format the same statistics to Nature, Science, Cell Press, clinical-grayscale or dark-slide conventions. - Every follow-up in the workspace chat recomputes the statistics from your data, so edits never drift from the numbers. - Finished figures export as PNG, JPG, SVG or PPTX through the canvas editor. #### How outliers are defined A point is an outlier when it falls more than 1.5 interquartile ranges outside the box. The whiskers end at the most extreme data points still inside those fences — not at the fences themselves. IQR = Q3 − Q1  fences: Q1 − 1.5 × IQR and Q3 + 1.5 × IQR #### Parts of a box plot Every element of a box and whisker plot answers one specific question about your data. - Box — What it shows: The middle 50% of the data | How it is computed: Spans Q1 to Q3 — the interquartile range - Median line — What it shows: The middle value | How it is computed: Half the observations sit on each side - Lower whisker — What it shows: Data reach below the box | How it is computed: To the smallest point at or above Q1 − 1.5 × IQR - Upper whisker — What it shows: Data reach above the box | How it is computed: To the largest point at or below Q3 + 1.5 × IQR - Whisker caps — What it shows: Where the whiskers end | How it is computed: Short bars at the last data point, never at the fence itself - Outliers — What it shows: Unusually extreme values | How it is computed: Individual points beyond the 1.5 × IQR fences - Mean marker — What it shows: The arithmetic mean (optional) | How it is computed: Drawn on request, usually as an open diamond - Value axis — What it shows: The measurement scale | How it is computed: Regular tick steps covering every group, whiskers and outliers Quartiles use linear interpolation (R type 7) — the same method as NumPy, Excel and Google Sheets, so the numbers here match your spreadsheet’s. #### Box plot vs histogram vs violin plot Three ways to show a distribution — which one fits depends on what the reader should compare. - What it shows — Box plot: Five-number summary plus outliers | Histogram: The full shape of one distribution | Violin plot: A smoothed density with a summary inside - Best for — Box plot: Comparing several groups side by side | Histogram: One variable’s distribution in detail | Violin plot: Comparing distribution shapes of larger samples - Works from — Box plot: As few as ~5 points per group | Histogram: Enough points to fill meaningful bins | Violin plot: Enough points to estimate a density - Outliers — Box plot: Marked as individual points | Histogram: Hidden inside the end bins | Violin plot: Usually not marked - Bimodality — Box plot: Invisible — the box can’t show two peaks | Histogram: Visible as two peaks | Violin plot: Visible in the density outline If the story is “group A runs higher than group B”, a box plot says it fastest. Reach for a histogram or violin plot when the shape of the distribution is itself the story. #### Where box plots are used Any time several groups of measurements need comparing at a glance, a box plot is the standard answer. - Treatment comparisons: Dose–response experiments, drug vs vehicle, pre vs post — the side-by-side boxes make shifts in median and spread visible instantly, with outlier animals or samples flagged honestly. - Quality control: Batch-to-batch variation, instrument drift, inter-operator spread — a box per batch shows both the level and the consistency, and outlier runs stand out as points. - Teaching statistics: The five-number summary, quartiles and the 1.5 × IQR outlier rule all live in one figure — which is why box plots anchor descriptive-statistics units from middle school through university. - Survey and A/B results: Response times, scores and ratings across cohorts or variants — box plots compare a dozen segments in one figure where a table of means would hide the spread. #### Box plot questions, answered **How do you read a box plot?** Read the median line first, then the box, then the whiskers. The line inside the box is the median — half the data sits on each side. The box covers the middle 50% (Q1 to Q3), so a taller box means more spread. The whiskers show the range of typical values, and any separate points beyond them are outliers worth a second look. **What do the whiskers on a box plot show?** The whiskers span the data outside the box that still counts as typical — from each box edge to the most extreme observation within 1.5 interquartile ranges. They end on a real data point, never on the fence value itself, which is why the two whiskers are usually different lengths. **How are the quartiles calculated?** This tool uses linear interpolation between order statistics — the method NumPy, Excel and Google Sheets use by default (R’s type 7). Textbooks sometimes teach a different rule (splitting the halves around the median), which is why two tools can give slightly different Q1 and Q3 for the same data. Whichever the method, the median itself always agrees. **Can I use this as a box plot calculator?** Yes — before anything is drawn, the tool works as a box and whisker plot calculator: paste data and the exact n, min, Q1, median, Q3, max and outliers of every group appear instantly. The same table doubles as a five number summary calculator and an interquartile range calculator — IQR is Q3 − Q1, and the 1.5 × IQR outlier fences are applied automatically. Checking the statistics costs nothing; generation is only spent when you draw the figure. **What counts as an outlier in a box plot?** Any value more than 1.5 × IQR below Q1 or above Q3. This is Tukey’s convention, and it flags roughly 0.7% of normally-distributed data — so an occasional outlier point is expected, not automatically an error. Outliers are drawn as individual points so the reader can count them. **Can I make a box plot from an Excel or CSV file?** Yes — attach up to three .xlsx, .csv or .tsv files with the composer’s upload control, or paste the values straight into the prompt. One column per group with a header row works, and so does the long format of a label column plus a value column. The exact statistics of every group appear immediately, before any generation is spent. **How many groups can one box plot compare?** Up to 12 groups on one axis. Beyond that the boxes get too narrow to read and reviewers will ask you to split the figure anyway. If your file has more columns, the panel keeps the first 12 and tells you what it skipped. **Can I make a horizontal box plot?** Yes — just say “horizontal” in the description. Horizontal boxes are the better choice when group names are long, and standard in clinical journals. Everything else — statistics, styles, editing — works identically in both orientations. **Does the AI change or invent my numbers?** No. The quartiles, whiskers and outliers are computed exactly from your data by code, and the AI is instructed to draw precisely those values. Every regeneration recomputes from the original data, so iterating on the style never drifts the statistics. **Is a box plot the same as a box and whisker plot?** Yes — the two names describe the same chart. “Box and whisker plot” (or box-and-whisker diagram) is the longer teaching name; “box plot” or “boxplot” is what statistics software and journals call it. Both were popularized by John Tukey in 1977. The tools inherit every combination of the names — box plot maker, boxplot generator, box and whisker plot creator — and they all draw this same chart. **Can I show the mean on a box plot?** Yes — ask for a mean marker and each box gets one, usually an open diamond. The box plot itself is built around the median because it resists outliers; showing both is standard when readers will want to connect the figure to reported means. **What export formats are available?** PNG and JPG directly, and SVG or PPTX through the canvas editor, which splits the figure into editable elements first. That covers manuscript submission (vector), slide decks (PPTX) and quick sharing (PNG). **Is this box plot maker free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. That covers generating and exporting real figures before you decide whether to buy credits or subscribe. An account is needed because each figure is saved to a workspace you can return to and edit. #### Sources - NIST/SEMATECH e-Handbook of Statistical Methods — Box Plot — National Institute of Standards and Technology: https://www.itl.nist.gov/div898/handbook/eda/section3/boxplot.htm - Visualizing samples with box plots (Points of Significance) — Nature Methods: https://www.nature.com/articles/nmeth.2813 - quantile — R documentation of the nine quantile types — The R Project: https://stat.ethz.ch/R-manual/R-devel/library/stats/html/quantile.html --- ### Bar Graph Maker — Free Bar Chart Generator with Error Bars URL: https://scientificfigure.com/tools/bar-graph-maker Description: Free bar graph maker: paste data or upload Excel/CSV for exact means with SD, SEM or 95% CI error bars — simple, grouped or stacked, in journal styles. #### What is a bar graph? A bar graph (bar chart) shows one number per category as the length of a bar measured from zero. In research figures that number is usually a group mean, with error bars showing the SD, the SEM or a 95% confidence interval. - Paste values into the prompt or attach up to three CSV, TSV or Excel files — one column per group, label/value rows, or one value per category. - Means, standard deviations, standard errors and 95% confidence intervals are computed exactly before the AI draws a single bar. - Naming bars Cluster – Series (Day 1 – Control) draws grouped bars; adding the word “stacked” stacks them. - The value axis always starts at zero, and every regeneration in the workspace recomputes the bar heights from your data. - Journal presets format the same numbers to Nature, Science, Cell Press, clinical-grayscale or dark-slide conventions, with export to PNG, SVG or PPTX. #### SD, SEM and the 95% confidence interval The SD describes how spread out the observations are; the SEM and the 95% CI describe how precisely the mean is known. The error bar shows whichever you choose, so the figure legend has to say which. SD = √(Σ(x − x̄)² / (n − 1)) SEM = SD / √n 95% CI = x̄ ± t₀.₉₇₅, ₙ₋₁ × SEM #### Which error bar should you use? The same data gives very different error bars. Choose by what the reader should conclude, and name it in the legend. - SD — What it shows: Spread of the individual observations | How it is computed: √(Σ(x − x̄)² / (n − 1)) | Use it when: Readers should see how variable the data are - SEM — What it shows: Precision of the mean | How it is computed: SD ÷ √n | Use it when: You compare means and give n in the legend - 95% CI — What it shows: Plausible range of the true mean | How it is computed: Mean ± t × SEM | Use it when: Readers should judge a difference by eye - None — What it shows: The value alone | How it is computed: — | Use it when: Each bar is a single count or total (n = 1) - Data points — What it shows: Every observation | How it is computed: Your raw values, drawn as dots | Use it when: Samples are small and the distribution matters SEM bars are narrower than SD bars by a factor of √n, which is why the legend must say which one is shown. In a 2015 review of 703 physiology papers, 85.6% contained a bar graph, and most of those showed mean ± SE (77.6%) rather than mean ± SD (15.3%). #### Bar graph vs histogram vs box plot A bar graph compares one number across categories, a histogram shows how one variable is distributed, and a box plot compares whole distributions across groups. - What the category axis holds — Bar graph: Separate groups or categories | Histogram: Bins of one continuous variable | Box plot: Separate groups - What each mark encodes — Bar graph: One value — a mean, count or percentage | Histogram: How many observations fall in the bin | Box plot: Median, quartiles, whiskers and outliers - Gaps between bars — Bar graph: Yes — the categories are distinct | Histogram: No — the bins touch | Box plot: Not applicable - Shows the distribution — Bar graph: Only with error bars or overlaid points | Histogram: Yes, in detail | Box plot: Yes, as a five-number summary - Best for — Bar graph: Counts, totals, percentages and group means | Histogram: One variable with many observations | Box plot: Groups with skew or outliers Bar graphs are designed for categorical comparisons. When each bar is the mean of a small sample, many different datasets can produce the same bars — overlay the individual points or use a box plot when the distribution is part of the story. #### Where bar graphs are used Bar graphs are the default whenever a figure compares a handful of means, counts or percentages across groups. - Treatment vs control: Expression levels, viability, tumor volume: one bar per condition with mean ± SD or SEM is the standard first panel of an experiment, and the axis from zero keeps the effect size honest. - Time courses by group: Grouped bars put control and treated side by side at each time point, so the divergence reads left to right without implying the continuity of a line plot. - Counts and surveys: Species per site, patients per category, responses per answer — one value per bar and no error bar needed. - Composition: Bars stacked to 100% show how a whole divides — cell-cycle phases, cell types, response categories — sample by sample. #### Bar graph questions, answered **How do I make a bar graph from my data?** Paste the values into the description or attach a CSV or Excel file, describe the axes, and generate. A bar can be a list of replicates (Control: 4.1, 5.2, 4.8) or a single value (Oak: 42). The means and error bars are computed first and shown above the box, so you can check them before anything is drawn. **Can I make a bar graph from Excel?** Yes — attach up to three .xlsx, .csv or .tsv files. One column per group with a header row works, and so does a label column next to a value column. Re-save a legacy .xls file as .xlsx or CSV first. **Should I use SD or SEM error bars?** Use the SD to show how variable the observations are, and the SEM or a 95% CI to show how precisely each mean is estimated. SD is the default here; type “SEM”, “standard error” or “95% CI” to switch. Whichever you use, state it and n in the figure legend. **How do I make a grouped bar chart?** Name each bar Cluster – Series, for example Day 1 – Control and Day 1 – Treated. Bars that share a cluster sit side by side, each series keeps one color across every cluster, and a legend names each series once. **How do I make a stacked bar chart?** Name the segments the same way (HeLa – G1, HeLa – S) and include the word “stacked” in your description. Segments stack in the order you list them, their boundaries are computed as running totals, and percentages that add up to 100 get an axis from 0 to 100. **Why does the axis start at zero?** Because a bar shows its value by its length, and a bar cut off above zero exaggerates the differences. This maker always draws bars from a zero baseline; negative values extend below it. **Can I show individual data points on the bars?** Yes — ask for “individual data points” and every observation is drawn as a dot over its bar. Reviewers increasingly ask for this with small samples, because very different datasets can share the same mean and error bar. **Can I make a horizontal bar chart?** Yes — say “horizontal” in the description. Horizontal bars suit long category names; the values, error bars and styles work the same in both orientations. **What is the difference between a bar graph and a bar chart?** There is none — they are two names for the same chart. “Bar graph” is more common in schools, “bar chart” in statistics software, and spreadsheets call vertical bars a column chart. **Does the AI change or invent my numbers?** No. Bar heights, error bars and axis ticks are computed from your data by code, and the AI is instructed to draw exactly those values. Every regeneration recomputes them from the original numbers, so restyling never moves a bar. **What export formats are available?** PNG and JPG directly, and SVG or PPTX through the canvas editor, which splits the figure into editable elements first — vector for manuscripts, PPTX for slides. **Is this bar chart generator free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. Computing the means and error bars costs nothing; credits are spent only when you generate the figure. Whether you call it a bar graph generator or a bar chart maker, it is the same tool: your numbers in, an exact figure out. #### Sources - Beyond Bar and Line Graphs: Time for a New Data Presentation Paradigm — PLOS Biology: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002128 - Error bars (Points of Significance) — Nature Methods: https://www.nature.com/articles/nmeth.2659 - Bar charts and box plots (Points of View) — Nature Methods: https://www.nature.com/articles/nmeth.2807 --- ### Histogram Maker: Free Histogram Generator with Exact Bins URL: https://scientificfigure.com/tools/histogram-maker Description: Histogram maker and builder: paste raw data or upload Excel/CSV, get every bin edge and count computed exactly, then a journal-style histogram. #### What is a histogram? A histogram shows how one continuous variable is distributed: its range is cut into adjacent bins, and the area of each bar stands for the number of observations in that bin. The bars touch because the bins cover an unbroken number line, which is what separates a histogram from a bar graph of separate categories. - Type or paste raw values (Diameter (µm): 5.3, 4.9, 5.0…), or attach as many as three spreadsheets (CSV, TSV or Excel) with one sample per column. - A two-column table of bin ranges and counts (10–15, 4) is treated as data already grouped and drawn as given, with class limits such as 50–59 joined at the boundaries 49.5 and 59.5. - Bins default to Sturges' rule with round edges; a stated bin width, bin count, Freedman–Diaconis or Scott's rule overrides it, and whole numbers over a short range get one bar per value. - Each bin holds its left edge and not its right, except the last bin, which holds both, so a value on an edge is counted once and in a predictable place. - Every regeneration recounts the bins from your values, so switching the journal preset or the colours never moves a bar. #### How many bins? Sturges, Freedman–Diaconis and the bin width The bin width decides what shape a histogram shows: too few bins hide a second peak, too many turn the bars into noise. A rule makes the choice reproducible, and the figure legend should state the width that was used. Sturges: k = ⌈log₂ n⌉ + 1 Freedman–Diaconis: h = 2 × IQR × n^(−1/3) Density: height = count ÷ (n × h) #### Reading the shape of a histogram A histogram is read for its center, spread, skewness, number of peaks and outliers, the features that point to the right model for the data. Bin width changes what you see, so check a shape at a second width before reporting it. - Symmetric, one peak — What the bars do: Tallest in the middle, falling off evenly on both sides | What it often means: Close to a normal distribution | What to check: A normal probability plot before a t-test - Right-skewed — What the bars do: A long tail of short bars to the right of the peak | What it often means: Values bounded at zero: sizes, times, concentrations | What to check: Report the median; try log-scale bins - Left-skewed — What the bars do: The long tail runs to the left | What it often means: A ceiling, such as exam scores near 100% | What to check: Median and IQR in the legend - Bimodal — What the bars do: Two separate peaks | What it often means: Two populations mixed in one sample | What to check: Split by group and overlay the two - Uniform — What the bars do: Bars of roughly equal height | What it often means: No preferred value, or bins too wide | What to check: Redraw with a narrower bin width - Outliers or gaps — What the bars do: Isolated bars far from the rest, empty bins between | What it often means: Measurement errors or a rare subgroup | What to check: Check those observations before excluding any Skewness is named after the tail, not the peak: a right-skewed histogram has its peak on the left. In a right-skewed sample the mean sits to the right of the median, which is why both are worth stating in the legend. #### Histogram vs bar graph A histogram bins one continuous measurement to show its distribution; a bar graph gives one value to each of several separate categories. Read the x axis to tell them apart: a numeric scale means a histogram, group names mean a bar graph. - X axis — Histogram: A number line divided into bins | Bar graph: Category names in any order | Box plot: Group names - Bar height — Histogram: Observations in the bin, or their density | Bar graph: A mean, count or percentage per category | Box plot: No bars: median, quartiles and whiskers - Space between bars — Histogram: None, neighbouring bins share an edge | Bar graph: Equal gaps between categories | Box plot: Boxes stand apart - Can the order change? — Histogram: No, bins follow the number line | Bar graph: Yes, by size or by name | Box plot: Yes - Answers — Histogram: Which values are common, and how spread out? | Bar graph: Which category is largest? | Box plot: How do whole groups compare? To compare one measurement across groups, one histogram per group on shared bins shows each full shape; past three groups a box plot makes the same comparison more compactly. #### When a journal figure needs a histogram Histograms appear wherever a paper has to show what a sample looks like, not only its mean. - Distribution checks before a test: Reviewers ask whether data meet the normality assumption of a t-test or ANOVA; a density histogram with a normal curve answers that in one supplementary panel. - Regression residuals: Standardized residuals centred on zero with no long tail support a linear model; skewed or two-peaked residuals point to a missing variable or a needed transformation. - Quality control and calibration: Fill weights, assay replicates or instrument readings binned against their specification limits show drift and spread at a glance in methods and validation papers. - Size and timing distributions: Cell and particle diameters, mitochondrial lengths, reaction times, ages at diagnosis: right-skewed or multimodal variables whose shape a mean ± SD bar would hide. #### Histogram questions, answered **How many bins should a histogram have?** Usually five to 15, with more bins as the sample grows. Sturges' rule gives 7 bins for 50 values, 8 for 100 and 11 for 1,000. This maker starts there and rounds the width to a clean number, so the final count can differ by one or two; large or skewed samples often read better with the Freedman–Diaconis rule. **Why do the bars in a histogram touch?** Because the bins are consecutive intervals of one number line with nothing between them. A gap would suggest values that cannot occur. Bars only stand apart when a bin is empty, which shows as a stretch of bare baseline. **What is the difference between a histogram and a bar chart?** A histogram shows the distribution of one numerical variable in bins; a bar chart compares a value across categories. The histogram's x axis is a continuous scale with touching bars, while a bar chart's categories stand apart and can be put in any order. **How do I choose the bin width?** Start from a rule, then take a round width near it: 2, 5 or 10 units rather than 3.7. Write “bin width 5” to set it and “starting at 40” to place the first edge. Too wide merges real peaks and too narrow makes noise look like structure, so compare two widths before deciding. **How do I tell whether a histogram is skewed?** Look at the tail: short bars trailing off to the right mean right-skewed, to the left mean left-skewed. The mean is pulled toward the tail, so a mean well above the median confirms a right skew. Reaction times, incomes and particle sizes are typically right-skewed. **When should a histogram use log-scale bins?** When every value is positive and the data span more than one or two powers of ten, as particle sizes and concentrations often do. Equal bins on a log axis give the small values room and often turn a long right tail into a symmetric shape. Write “log bins” or “x axis on a log scale”. **How do you draw a histogram by hand?** Find the range, choose a bin width, tally the values into the bins, then draw touching bars as tall as the counts. Start the first bin just below the smallest value; with whole numbers, edges ending in .5 (49.5, 59.5) keep any value from landing on an edge. The steps are the same in a notebook as here. **Should the y axis show frequency, relative frequency or density?** Frequency for a single sample, relative frequency to compare samples of different sizes, density when a probability curve is drawn over the bars or the bins are unequal. With equal bins all three give the same shape; only the scale on the axis changes. **How do I compare two groups with histograms?** Put both samples on the same bin edges and the same axes, overlaid with transparent fills or in panels one above the other. Separate bins for each group make the shapes impossible to compare. Give each group its own line of values with its name. **Which bin does a value on a bin edge go into?** The bin that starts at that edge. Each bin includes its left edge and excludes its right one, except the last bin, which includes both ends so the maximum is always counted; NumPy's histogram function uses the same convention. **Can I create a histogram from data already grouped into classes?** Yes. Give the classes with their counts, such as 40–49: 3, 50–59: 8, 60–69: 12, and they are drawn as given. The limits are joined at the class boundaries so the bars touch, and when classes differ in width the bars switch to frequency density so their areas stay proportional to the counts. **What should a histogram's figure legend state?** The sample size, the bin width or the rule that chose it, and what the y axis measures. A reader cannot judge a shape without knowing the bin width, and a density axis needs one sentence for readers outside statistics. #### Sources - 1.3.3.14. Histogram — NIST, e-Handbook of Statistical Methods: https://www.itl.nist.gov/div898/handbook/eda/section3/histogra.htm - 2.2 Histograms, Frequency Polygons, and Time Series Graphs — OpenStax, Introductory Statistics 2e: https://openstax.org/books/introductory-statistics-2e/pages/2-2-histograms-frequency-polygons-and-time-series-graphs --- ### Line Graph Maker: Free Line Graph Generator & Creator URL: https://scientificfigure.com/tools/line-graph-maker Description: Make a line graph from time points or a CSV/Excel table: exact points, SD or SEM error bars and log axes are computed, then drawn as a journal-ready figure. #### What is a line graph? A line graph plots a measured value against an ordered x variable, usually time or dose, and joins successive points with line segments so the reader sees how the value changes. Each line is one condition or group. Because the x axis is a number line, or an ordered set of visits, the spacing between points carries meaning, and the slope between two points is the rate of change over that interval. In research figures the points are usually means, each with an error bar. - Type the x values once (Time (h): 0, 2, 4, 8) and one line per condition, or attach a CSV, TSV or Excel table with x in the first column and one column per line, up to 6 lines and 40 x values. - Columns that share a header are read as replicates and averaged in code. Error bars are SD by default, SEM or a 95% CI when you name them, and a column headed like “KO SD” becomes that line's ± values. - Uneven sampling times keep their true spacing on the x axis. Ask for a log x axis for concentrations or a log y axis for counts and OD, and the ticks land on powers of ten. - Each line gets its own marker shape, the legend lists the lines in the order they end on the right, and it goes in a corner of the plot the data leave empty. - Every regeneration rebuilds the points from your data; a new journal preset or palette restyles the lines and leaves each point where it was. #### Slope, growth rate and doubling time from a line graph The slope between two points of a line graph is the average rate of change over that interval; on a semi-log growth curve the slope of the straight stretch is the specific growth rate, which sets the doubling time. rate = (y₂ − y₁) / (x₂ − x₁) μ = (ln N₂ − ln N₁) / (t₂ − t₁) t_d = ln 2 / μ #### Choosing the axes and error bars for your data Most line graph mistakes are axis choices: evenly spaced ticks for uneven times, a linear axis for values that grow a thousandfold, a second y axis. Match your data to the setting. - Samples at 0, 1, 2, 4, 8 and 24 h — X axis: Linear time at the true spacing | Y axis: Linear | Error bars: SD or SEM of independent repeats - OD600 or CFU/mL during growth — X axis: Linear time | Y axis: Log₁₀ (semi-log plot) | Error bars: SD of biological replicates - Response at 0.1 to 10,000 nM — X axis: Log₁₀ concentration | Y axis: Linear, % of control | Error bars: SEM or 95% CI - Visits at baseline and weeks 4, 12, 24 — X axis: Weeks as numbers, or visits as evenly spaced labels | Y axis: Change from baseline, crossing 0 | Error bars: 95% CI - Two variables in different units — X axis: One shared time axis | Y axis: Two stacked panels, one y axis each | Error bars: As for each variable - One representative experiment — X axis: As above | Y axis: As above | Error bars: None, since n = 1 Error bars belong to independent repeats, not technical replicates. A single representative run has n = 1 and carries no error bars, and replicate wells from one run show pipetting precision rather than biological variation (Cumming, Fidler and Vaux, 2007). #### Line graph questions, answered **How do I make a line graph from my data?** Type the x values once, then one line per group, or attach the spreadsheet. For example: Time (h): 0, 2, 4, 8. Control: 0.05, 0.12, 0.31, 0.9. Treated: 0.05, 0.09, 0.18, 0.4. Add “mean ± SEM” with replicates written 0.05/0.06/0.05 per point for error bars, “log y axis” for growth data, and axis titles in quotes. The points and ticks are computed from those numbers before anything is drawn. **Line graph or scatter plot: which should I use?** Use a line graph when x is ordered and each point follows from the one before it, as with time, dose or visit; use a scatter plot when each x–y pair is an independent observation. Joining points claims a continuous change between them, which holds for a time course and not for, say, height against weight across people. For paired measurements with a trend line or a correlation, use the scatter plot maker. **Should a line graph show SD or SEM?** SD to describe how much the measurements vary, SEM or a 95% confidence interval to compare means. Whichever you choose, the legend must name it and give n, the number of independent experiments or animals behind each point (Cumming, Fidler and Vaux, J Cell Biol 2007). With n = 3, plotting the individual values is often clearer than any error bar. **When should the y axis of a line graph be logarithmic?** When the values span more than about one order of magnitude and change by multiplication, as in bacterial growth, viral titres or serial dilutions. On a log axis equal ratios take equal distances, so steady exponential growth draws as a straight line. Every value must be above zero: a count of 0 cannot be placed, so the tool keeps a linear axis and says why. **Can a line graph have two y axes?** Not here, and many journals discourage it: where two lines cross on a dual-axis plot depends only on how each axis range was chosen. Ask for two y axes or for separate panels and the tool draws stacked panels on one shared x axis, each with its own y axis and ticks. **Why are my time points not evenly spaced on the x axis?** Because they were not evenly spaced in time. Samples at 0, 1, 2, 4, 8 and 24 h sit at their true positions, so the slope between two points is a real rate. If the x values are visit names rather than times, type them as labels (Baseline, Week 4, Week 12) and they are spaced evenly in the order given. **Should the points be joined by straight lines or a smooth curve?** Straight segments, unless you have a model. A straight segment claims nothing about what happened between measurements; a smooth curve suggests values nobody measured, and a fitted sigmoid needs fitted parameters. Ask for a smooth curve and it passes exactly through every point without overshooting; for a fitted dose-response, fit it in your statistics software and supply the curve's values. **What should the figure legend of a line graph say?** What the points are, what the error bars are, the n behind each point, and what the lines join. For example: “Blood glucose after an oral glucose load in wild-type and db/db mice. Points are means ± SEM, n = 4 mice per group; lines join consecutive time points.” Add the statistical test if the figure marks significance. **How many lines can one line graph hold?** Up to six lines of up to 40 points each here, though four or five is the practical limit for a reader. Each line gets its own colour and marker shape (circle, square, triangle, diamond, inverted triangle, hexagon) and, in the grayscale presets, its own dash pattern. Beyond that, split the conditions into panels. **Is a line chart the same as a line graph?** Yes: line chart is the usual name in spreadsheet and business software, line graph the usual name in school and science. Both plot values against an ordered x axis and join them with lines. A run-sequence plot is a line graph of measurements in the order they were taken, used to spot shifts and drift (NIST/SEMATECH e-Handbook). **Does the AI change my numbers?** No: each point reaches the image model as an exact coordinate. Replicate means, the SD, SEM or 95% CI ends, both axis ranges, the tick labels and the legend order are computed in code from your data on every generation, and the model is told to place each point at its stated value without averaging, smoothing or re-ordering anything. #### Sources - Error bars in experimental biology — Cumming, Fidler and Vaux, Journal of Cell Biology (2007): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2064100/ - 1.3.3.25. Run-Sequence Plot — National Institute of Standards and Technology (NIST): https://www.itl.nist.gov/div898/handbook/eda/section3/runseqpl.htm --- ### Heatmap Generator — Free Heat Map Maker from Excel or CSV URL: https://scientificfigure.com/tools/heatmap-generator Description: Free heatmap generator: paste a table or upload Excel/CSV for an exact, color-binned heat map — gene expression, correlation matrices, color-blind-safe maps. #### What is a heatmap? A heatmap (heat map) shows a table of numbers as a grid of colored cells, one row and one column per label. Color encodes each value, so patterns across rows and columns — gradients, blocks, outliers — read at a glance. - Paste a table copied from Excel, type it as Columns: … plus one Row: values line per row, or attach a CSV, TSV or Excel file. - Row labels come from the first column and column labels from the header row; blank or NA cells are drawn as missing. - Every value is binned by code into five color steps with round boundaries, and the colors are written into the prompt cell by cell. - Data that crosses zero gets a diverging scale centered on 0 automatically, and “row z-scores” scales each row before binning. - Grids up to 12 × 12 are accepted; beyond that image models start miscounting cells, so the tool asks you to trim instead of guessing. #### How row z-scores are computed A row z-score says how many standard deviations a cell sits above or below the mean of its own row. Gene expression heatmaps use it so every gene is compared on the same scale, whatever its absolute level. z = (x − row mean) / row SD #### Choosing a color map The right color map depends on what the numbers mean, not on taste. - Blues — Type: Sequential | Use it for: Counts, concentrations, expression from low to high | Why: Darkness rises with the value, so darker always means more - Viridis — Type: Sequential, perceptually uniform | Use it for: Figures that must survive color-vision deficiency and grayscale printing | Why: Equal steps in the data look like equal steps in color - Blue–white–red — Type: Diverging | Use it for: Z-scores, log fold changes, correlations from −1 to 1 | Why: White marks zero and the two hues show direction - Grayscale — Type: Sequential | Use it for: Black-and-white print and photocopies | Why: Readable without any color at all - Rainbow (jet) — Type: Avoid | Use it for: — | Why: Uneven lightness invents boundaries that are not in the data - Red–green — Type: Avoid | Use it for: — | Why: Unreadable with the most common forms of color blindness Color-vision deficiency affects about 8% of men and 0.5% of women worldwide, which is why red–green and rainbow scales keep a figure from part of its readership. #### Heatmap vs clustered heatmap vs table A heatmap keeps your rows and columns in the order you give, a clustered heatmap reorders them by similarity and adds dendrograms, and a table shows exact numbers without the pattern. - Row and column order — Heatmap: As supplied — time, dose or your own order | Clustered heatmap: Reordered by hierarchical clustering | Table: As supplied - Shows patterns at a glance — Heatmap: Yes | Clustered heatmap: Yes, grouped by similarity | Table: No - Exact values — Heatmap: Printed in the cells when there is room | Clustered heatmap: Rarely — usually too many cells | Table: Always - Typical size — Heatmap: A few to a dozen rows and columns | Clustered heatmap: Dozens to thousands of rows | Table: Any size, but hard to scan - Made with — Heatmap: This generator | Clustered heatmap: Clustering software such as R pheatmap or seaborn clustermap | Table: A spreadsheet This generator draws ordered heatmaps and computes no clustering. If your analysis clustered the rows, paste them in that order and add the dendrogram from the analysis software, where its branch heights are real. #### Where heatmaps are used Heatmaps are used wherever a matrix of values has a pattern worth seeing — across genes, samples, doses or time. - Gene expression: Genes as rows, samples or conditions as columns, often as row z-scores on a diverging scale — the standard summary panel of an RNA-seq or qPCR experiment. - Correlation matrices: Pairwise Pearson or Spearman coefficients from −1 to 1 on a blue–white–red scale, with 1 on the diagonal, to show which variables move together. - Dose–response grids: Viability or synergy across the concentrations of two drugs, where the gradient across the grid is the finding. - Classifier evaluation: Confusion matrices with true classes as rows and predicted classes as columns, and the count printed in each cell. #### Heatmap questions, answered **How do I make a heatmap from my data?** Paste the table into the description or attach a CSV or Excel file, pick a color map and generate. Put row labels in the first column and column labels in the first row. The binned grid is shown above the box before any credit is spent. **Can I make a heatmap from Excel?** Yes — attach an .xlsx file, or copy the cells in Excel and paste them straight into the description. The sheet with the most numbers is used, and blank or NA cells are drawn as missing rather than as zero. **How do I make a gene expression heatmap?** Put genes in rows and samples in columns, then pick a map — or write “row z-scores” to scale each gene to its own mean and SD. Z-scored data is drawn on a blue–white–red scale centered on zero, the usual convention for expression panels. **How do I make a correlation heatmap?** Paste the correlation matrix with the same labels on rows and columns. Values that cross zero get a diverging scale from −1 to 1 automatically, with each coefficient printed in its cell. The tool plots coefficients you have computed; it does not compute them from raw data. **Which color map should I use for a heatmap?** Sequential maps (blues, viridis) for values from low to high, a diverging map (blue–white–red) for values either side of a meaningful zero, grayscale for black-and-white print. Avoid rainbow and red–green scales: they distort the data and lose readers with color-vision deficiency. **How big can the heatmap be?** Up to 12 rows and 12 columns. Beyond that, image models start miscounting cells, so the tool refuses a larger table rather than drawing a wrong grid — trim it, aggregate it or split the figure into panels. **Can I hide the numbers in the cells?** Yes — write “no values” or “without numbers” in the description. Values are printed by default, in white on the darker colors and in black on the lighter ones. **Does the heatmap include clustering or a dendrogram?** No — rows and columns keep the order you give, and no clustering is computed. If your analysis clustered them, paste the rows in that order and add the dendrogram from your analysis software. **Why are the colors in steps instead of a smooth gradient?** Because five discrete bins can be drawn exactly — each cell is told its bin and its hex color — while a continuous gradient would leave the AI to guess every shade. The bin boundaries are round numbers printed on the color bar, so each cell’s range stays readable. **Does the AI change or invent my numbers?** No. The bins, colors and printed values are computed by code from your table and written into the prompt cell by cell. Every regeneration recomputes them, so switching the color map never moves a value into the wrong bin. **Is a heat map the same as a heatmap?** Yes — heat map, heatmap and heat-map are spellings of the same chart. Analysis software mostly writes “heatmap”; general writing often uses “heat map”. **Is this heatmap generator free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. Previewing the binned grid costs nothing; credits are spent only when you generate the figure. Search for a heat map generator, a heatmap creator or a heatmap maker and you land on the same thing: a table in, an exact colour-binned grid out. #### Sources - Heat maps (Points of View) — Nature Methods: https://www.nature.com/articles/nmeth.1902 - The misuse of colour in science communication — Nature Communications: https://www.nature.com/articles/s41467-020-19160-7 --- ### Bode Plotter — Free Bode Plot Generator & Calculator URL: https://scientificfigure.com/tools/bode-plotter Description: Free Bode plotter online: type a transfer function and get exact magnitude and phase curves, corner frequencies, and gain and phase margins, drawn for print. #### What is a Bode plot? A Bode plot shows a linear system’s frequency response as two graphs on a shared logarithmic frequency axis: magnitude in decibels on top and phase in degrees below. Each pole and zero bends the magnitude by a fixed slope at its corner frequency, so the shape of G(s) can be read straight off the plot. - Type G(s) as a factored expression such as 100/((s+1)(s+100)), as MATLAB-style coefficient lists num = [1 10], den = [1 3 2], or as K, zeros and poles — complex roots like −1±2j included. - Symbols are substituted when you define them: write ωn²/(s²+2ζωn s+ωn²) with ζ = 0.2 and ωn = 10. - Roots, corner frequencies, slopes, a resonance peak, the gain and phase crossovers and both stability margins are computed by code before anything is drawn. - The frequency axis spans two decades either side of the corners, in rad/s — or in Hz when you ask for Hz. - Numerator and denominator up to degree 8; right-half-plane zeros and poles are plotted as computed. #### How the magnitude in dB is computed The magnitude is 20 times the base-10 logarithm of |G(jω)|, and the phase is the angle of G(jω) in degrees. A factor of 10 in gain is +20 dB, a factor of 0.1 is −20 dB, and |G| = 1 is 0 dB. |G(jω)|dB = 20 · log₁₀ |G(jω)|, ∠G(jω) = Σ∠zeros − Σ∠poles #### What each factor does on a Bode plot Every Bode plot is the sum of a few standard factors, which is why the straight-line approximation works. - Gain K — Magnitude slope: 0 dB/decade, level 20·log₁₀|K| | Phase contribution: 0° (or ±180° if K < 0) | At the corner: — - Integrator 1/s — Magnitude slope: −20 dB/decade everywhere | Phase contribution: −90° at all frequencies | At the corner: Crosses 0 dB at ω = 1 - Real pole 1/(s/a + 1) — Magnitude slope: 0, then −20 dB/decade above a | Phase contribution: 0° to −90° | At the corner: −3 dB and −45° at ω = a - Real zero (s/a + 1) — Magnitude slope: 0, then +20 dB/decade above a | Phase contribution: 0° to +90° | At the corner: +3 dB and +45° at ω = a - Complex pole pair (ωn, ζ) — Magnitude slope: 0, then −40 dB/decade above ωn | Phase contribution: 0° to −180° | At the corner: −90° at ωn; a peak when ζ < 0.707 - Right-half-plane zero (1 − s/a) — Magnitude slope: 0, then +20 dB/decade above a | Phase contribution: 0° to −90° | At the corner: Adds lag like a pole — non-minimum phase The straight-line (asymptotic) Bode plot is off by at most 3 dB at a real corner, but a lightly damped pair can peak far above it — at ζ = 0.2 the resonance is about +8 dB. #### Bode plot vs Nyquist plot vs Nichols chart All three show the same frequency response G(jω): a Bode plot splits it into magnitude and phase against frequency, a Nyquist plot traces it as one curve in the complex plane, and a Nichols chart plots magnitude against phase. - Axes — Bode plot: Frequency (log) vs dB, and vs degrees | Nyquist plot: Real part vs imaginary part | Nichols chart: Phase (deg) vs magnitude (dB) - Frequency visible — Bode plot: Yes, on the x-axis | Nyquist plot: Only as labels along the curve | Nichols chart: Only as labels along the curve - Gain and phase margins — Bode plot: Read directly at the crossovers | Nyquist plot: Distance and angle to −1 | Nichols chart: Distance to the (−180°, 0 dB) point - Stability of unstable open loops — Bode plot: Not decidable from margins alone | Nyquist plot: Decided by the Nyquist criterion | Nichols chart: Not directly - Sketched by hand — Bode plot: Easily, with straight-line asymptotes | Nyquist plot: Harder | Nichols chart: Rarely Gain and phase margins read from a Bode plot assume a stable open loop. When G(s) has right-half-plane poles, the tool still plots and states the margins, but closed-loop stability needs the Nyquist criterion. #### Where Bode plots are used Bode plots are used wherever a system’s response depends on frequency — feedback control, filters, amplifiers and mechanical vibration. - Control-system design: Open-loop Bode plots with gain and phase margins marked, to size a controller and check how much gain or delay the loop tolerates. - Filter design: Low-pass, high-pass and band-pass responses with their cutoff frequencies and roll-off slopes, for analog circuits and signal processing. - Lead and lag compensators: The phase hump of a lead network and where its maximum lands, the standard figure of a controller-design report. - Coursework and exams: Clean textbook-style plots with asymptotes dashed, for lab reports, lecture slides and worked solutions. #### Bode plot questions, answered **How do I make a Bode plot from a transfer function?** Type the transfer function into the box — for example G(s) = 100/((s+1)(s+100)) — pick a style and generate. The magnitude and phase curves, corners and margins are drawn above the box before any credit is spent, and the figure is drawn from exactly those numbers. **How do I find the gain margin and phase margin from a Bode plot?** The phase margin is 180° plus the phase at the gain crossover, where the magnitude crosses 0 dB; the gain margin is minus the magnitude in dB at the phase crossover, where the phase crosses −180°. The tool computes both and marks them when you ask for “gain and phase margins marked”; if the phase never reaches −180°, the gain margin is infinite. **What is a corner frequency?** A corner (break) frequency is where a pole or zero starts to bend the magnitude — at ω equal to the size of the root. For a real pole the curve sits 3 dB below the straight-line approximation there and the phase is 45° past its starting value. **What slopes do poles and zeros add on a Bode plot?** Each real pole adds −20 dB per decade above its corner, each real zero +20 dB per decade, and a complex pair ±40 dB per decade. An integrator (a pole at s = 0) gives −20 dB per decade from the lowest frequency. **How do I convert magnitude to decibels?** Multiply the base-10 logarithm of the magnitude by 20: 20·log₁₀|G(jω)|. A gain of 10 is 20 dB, 100 is 40 dB, 0.707 is about −3 dB and 1 is 0 dB. **Is this the same as MATLAB’s bode() command?** It computes the same thing — |G(jω)| in dB and ∠G(jω) in degrees over a log frequency grid — and accepts the same num/den coefficient lists. The MATLAB style mimics bode()’s look with its blue curves and grid; the figure itself is drawn by the AI from the computed curves, so it is a figure, not a numeric export. **Can I plot a second-order system with damping ratio and natural frequency?** Yes — write ωn²/(s² + 2ζωn s + ωn²) with ζ = 0.2 and ωn = 10, or the numbers directly. A damping ratio below 0.707 gives a resonance peak, which is computed and drawn at its exact height and frequency. **What are the asymptotes on a Bode plot?** They are the straight-line approximation: flat or sloped segments meeting at the corner frequencies. The textbook style draws them as dashed lines behind the real curve; the other styles leave them out unless you ask for asymptotes. **Can the frequency axis be in Hz instead of rad/s?** Yes — write “in Hz” in the description and every frequency is divided by 2π. Otherwise the axis is in rad/s, the unit the transfer function in s is written in. **Does the AI change or invent the curves?** No. The roots, slopes, points on each curve, corners and margins are computed by code and written into the prompt. Every regeneration recomputes them from your transfer function, so switching the style never moves a corner. **Is this Bode plot calculator free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. The computed preview costs nothing; credits are spent only when you generate the figure. Search for a Bode plot maker, a Bode plot calculator or a Bode plot online and you land on the same thing: a transfer function in, an exact Bode plot out. #### Sources - bode — Bode frequency response of dynamic system — MathWorks (MATLAB documentation): https://www.mathworks.com/help/control/ref/dynamicsystem.bode.html - Control Systems Engineering, 8th Edition (Norman S. Nise) — Wiley: https://www.wiley.com/en-us/Control+Systems+Engineering%2C+8th+Edition-p-9781119474227 - Bode plot — Wikipedia: https://en.wikipedia.org/wiki/Bode_plot --- ### Lewis Structure Generator — Free Lewis Diagram & Dot Maker URL: https://scientificfigure.com/tools/lewis-structure-generator Description: Free Lewis structure and Lewis diagram generator: type a formula like CO2, NH4+ or SO4 2- and get the exact electron dot diagram — bonds, lone pairs, charges. #### What is a Lewis structure? A Lewis structure (Lewis diagram, Lewis dot structure, electron dot diagram) shows how the valence electrons of a molecule or ion are arranged: shared pairs as bond lines between element symbols, unshared pairs as dots. It is the first model of bonding taught in chemistry and the starting point for predicting shape, polarity and reactivity. - Type a formula anywhere in the description — CO2, H2SO4, NH4+, SO4 2-, [NO3]- or SO₄²⁻ — or a common name such as ammonia or ozone. - The structure is computed by code with the octet method: valence electrons are counted, the skeleton is built around the least electronegative atom, and every arrangement of single, double and triple bonds is scored by formal charge. - Equivalent resonance structures are counted, and expanded octets (SF6, XeF4, SO4 2-) and incomplete ones (BF3, BeCl2) are handled. - It covers diatomics, molecules and ions with one central atom, and two identical centres such as C2H4, N2H4 and H2O2; rings and longer chains are refused rather than guessed. - VSEPR geometry, the bond angle and polarity are shown next to the structure before anything is generated — a free Lewis structure calculator in the box itself. #### How formal charge is calculated Formal charge is the charge an atom would carry if every bond were shared equally: its valence electrons minus the electrons it keeps as lone pairs minus half the electrons in its bonds. The best Lewis structure keeps formal charges as close to zero as possible, with any negative charge on the most electronegative atom. FC = V − N − B/2 #### The octet method, step by step Every structure this generator draws follows the method taught in general chemistry — here it is applied to the sulfate ion, SO4 2-. - 1. Count valence electrons — What you do: Add the valence electrons of every atom; add one per negative charge, subtract one per positive charge | SO4 2- example: 6 + 4 × 6 + 2 = 32 - 2. Build the skeleton — What you do: Put the least electronegative atom in the center (never H) and join each outer atom with a single bond | SO4 2- example: S in the center, four S–O bonds (8 electrons) - 3. Complete the outer octets — What you do: Give each outer atom lone pairs until it has 8 electrons (H needs only 2) | SO4 2- example: Three lone pairs on each O (24 electrons) - 4. Place what is left — What you do: Any remaining electrons go on the central atom as lone pairs | SO4 2- example: None left: 32 − 8 − 24 = 0 - 5. Complete the central octet — What you do: If the center has fewer than 8, turn outer lone pairs into double or triple bonds | SO4 2- example: S already has 8 (octet form, S +2) - 6. Minimize formal charges — What you do: Prefer the arrangement with formal charges closest to zero; atoms from period 3 on may exceed 8 | SO4 2- example: Two S=O double bonds: S 0, two O −1 Steps 5 and 6 are where hand-drawn structures most often go wrong — this generator scores every arrangement of single, double and triple bonds and keeps the one with the lowest formal charges. #### Lewis structure vs structural formula vs molecular geometry A Lewis structure shows every valence electron, a structural formula shows only the bonds, and a molecular geometry (VSEPR) model shows the 3D shape. - Lone pairs — Lewis structure: Shown as dots | Structural formula: Usually left out | Molecular geometry (VSEPR): Count toward the shape; drawn as lobes, if at all - Formal charges — Lewis structure: Shown on each atom | Structural formula: Only net charges | Molecular geometry (VSEPR): Not shown - 3D shape — Lewis structure: Not shown — a flat 2D drawing | Structural formula: Sometimes, with wedges and dashes | Molecular geometry (VSEPR): Shown, with bond angles - Typical use — Lewis structure: Counting electrons, formal charge, resonance | Structural formula: Organic chemistry, reaction schemes | Molecular geometry (VSEPR): Predicting polarity and bond angles - Made with — Lewis structure: This generator | Structural formula: A chemical structure editor | Molecular geometry (VSEPR): A 3D model kit or molecular viewer The generator draws the Lewis structure and lists the VSEPR geometry and bond angle beside it; ask in the description if you want the shape written on the figure. #### Where Lewis structures are used Lewis structures are used wherever you need to see where the electrons are — in class, on exams and as the first step in predicting how a molecule behaves. - Worksheets and exams: Clean, correct structures for answer keys, practice sheets and quiz questions, in black and white that photocopies well. - Lecture slides: Element-colored structures that read from the back of a lecture hall, with formal charges and brackets where they belong. - Resonance and formal charge lessons: The equivalent resonance structures of nitrate, carbonate or ozone side by side, joined by resonance arrows. - Predicting shape and polarity: The Lewis structure is the input to VSEPR: count the bonding and lone pairs around the central atom to get the geometry and bond angle. #### Lewis structure questions, answered **How do you draw a Lewis structure?** Count the valence electrons, join the atoms with single bonds around the least electronegative atom, complete the outer octets, put leftover electrons on the center, then form double or triple bonds until the center has an octet. Type a formula in the box above to see the result of each step computed instantly. **How do you find the number of valence electrons?** Add the valence electrons of every atom (its group number for main-group elements), then add one for each negative charge and subtract one for each positive charge. CO2 has 4 + 2 × 6 = 16; NH4+ has 5 + 4 − 1 = 8; SO4 2- has 6 + 24 + 2 = 32. **What is the Lewis dot structure of water (H2O)?** Oxygen in the center bonded to two hydrogens by single bonds, with two lone pairs on the oxygen — 8 valence electrons in all. The molecule is bent, with an H–O–H angle of 104.5°. **How does the generator choose the central atom?** It puts the least electronegative atom other than hydrogen in the center — carbon before nitrogen, sulfur or phosphorus before oxygen, never hydrogen or fluorine. Oxyacids written H-first, such as H2SO4 or HNO3, get their hydrogens on oxygen. **Does it show formal charges?** Yes — every non-zero formal charge is drawn next to its atom, and ions are drawn in square brackets with the overall charge at the top right. Among the possible structures, the one with formal charges closest to zero wins. **Can it draw resonance structures?** Yes. It counts the equivalent resonance structures — 3 for nitrate, 2 for ozone, 6 for sulfate — and draws one by default. Ask for “all resonance structures” to get up to three side by side with resonance arrows. **What about expanded or incomplete octets?** Both are handled: atoms from period 3 on can hold more than 8 electrons (PCl5, SF6, XeF4), and boron and beryllium keep fewer (BF3 has 6 around boron). When an expanded octet lowers the formal charges, as in SO4 2-, the preview says so and names the all-octet alternative. **Which molecules does it not handle?** Rings, chains of three or more heavy atoms, condensed formulas such as CH3OH, C3H8 or C6H6, and ionic compounds like NaCl. It refuses these with a clear message instead of letting the AI guess a structure. **Is a Lewis diagram the same as a Lewis structure or an electron dot diagram?** Yes — Lewis diagram, Lewis structure, Lewis dot structure, Lewis dot diagram and electron dot diagram all name the same drawing. Some textbooks keep “Lewis symbol” for a single atom with its valence dots. **Does it show the molecular shape?** The preview lists the VSEPR class, the molecular geometry, the bond angle and the polarity next to the structure. The figure itself is the flat Lewis structure; ask in the description if you want the geometry written on it. **Is this Lewis structure generator free?** Yes to start — every new account gets {credits} free credits and no card is required to sign up. The computed structure in the preview costs nothing; credits are spent only when you generate the figure. Search for a Lewis structure maker, a Lewis structure drawer or a Lewis structure calculator and you land on the same thing: a formula in, an exact electron dot diagram out. #### Sources - 7.3 Lewis Symbols and Structures — OpenStax Chemistry 2e: https://openstax.org/books/chemistry-2e/pages/7-3-lewis-symbols-and-structures - 7.4 Formal Charges and Resonance — OpenStax Chemistry 2e: https://openstax.org/books/chemistry-2e/pages/7-4-formal-charges-and-resonance - Lewis formula (electron dot or Lewis structure) — IUPAC Gold Book: https://doi.org/10.1351/goldbook.L03513 --- ### Tree Diagram Maker & Probability Tree Diagram Generator URL: https://scientificfigure.com/tools/tree-diagram-maker Description: Probability tree diagram maker: type the branches or the problem and get a clean tree with every outcome multiplied out as a fraction, checked to add to 1. #### What is a tree diagram? A tree diagram is a branching diagram that lists every outcome of a sequence of events; in probability it is the probability tree, where each branch carries the probability of one outcome given the branches before it and multiplying along a path gives the probability of that path. Read from left to right, the first fan of branches is the first event (the first draw, toss or test result), each later fan repeats from the end of every earlier branch, and the end of each path is one outcome of the whole experiment. The branches leaving any point add to 1, and so do all the outcomes together. The same picture also serves decision trees, which add choices and payoffs, and hierarchy trees, which only show what belongs under what. - The products are computed, not guessed. Each outcome is multiplied out in code along its path and written as the product, the unsimplified fraction and the simplified one, for example 3/5 × 2/4 = 6/20 = 3/10. - Fractions stay fractions. Branches written as fractions keep their denominators, so the 2/4 of a second draw is not quietly turned into 1/2; decimals and percentages are multiplied as decimals and percentages. - A missing complement is filled in. When one branch at a point has no probability it gets 1 minus the others (No rain after Rain 0.3 becomes 0.7). Branches you give that add to more or less than 1 are drawn exactly as written, never corrected behind your back. - Events you name are summed. Ask for P(exactly one red), at least two heads, same color or a single result such as test positive, and the matching outcomes are added and written under the tree. - Sized to stay readable. Up to four stages and 48 outcomes in one tree: two dice (36 outcomes) fit, three dice (216) do not. #### The multiplication and addition rules behind every tree Multiply along a path to get the probability of that path, then add the paths that make up an event. The first rule is the general multiplication rule: every branch after the first stage is a conditional probability, the chance of B given that A has already happened. The second is the addition rule for mutually exclusive outcomes: two different paths of one tree can never both happen, so their probabilities simply add. P(A and B) = P(A) × P(B | A) P(event) = Σ P(path) #### Worked outcome table: two counters from 3 red and 2 blue The outcome column of the first example, laid out as a table. These are the numbers the tree writes at the end of each path. - Red, Red — Branches multiplied: 3/5 × 2/4 | Probability: 6/20 = 3/10 - Red, Blue — Branches multiplied: 3/5 × 2/4 | Probability: 6/20 = 3/10 - Blue, Red — Branches multiplied: 2/5 × 3/4 | Probability: 6/20 = 3/10 - Blue, Blue — Branches multiplied: 2/5 × 1/4 | Probability: 2/20 = 1/10 - All four paths — Branches multiplied: | Probability: 20/20 = 1 P(exactly one red) = 6/20 + 6/20 = 12/20 = 3/5. With replacement the second fractions would be 3/5 and 2/5 again, and P(Red, Red) would be 9/25 instead of 3/10. #### Tree diagram vs two-way table vs Venn diagram A tree diagram shows events in order with the conditional probabilities on its branches; a two-way table shows the same joint probabilities as a grid of cells; a Venn diagram shows overlaps between events but no order. - Order of events — Tree diagram: Shown, stage by stage | Two-way table: Not shown | Venn diagram: Not shown - Conditional probabilities — Tree diagram: Written on the later branches | Two-way table: Worked out from a row or column total | Venn diagram: Not shown directly - Joint probabilities — Tree diagram: At the end of each path | Two-way table: In each cell | Venn diagram: In each region - More than two stages — Tree diagram: One more fan per stage | Two-way table: Awkward beyond two variables | Venn diagram: Awkward beyond three sets - Best for — Tree diagram: Draws, tosses and tests in sequence | Two-way table: Survey counts split by two categories | Venn diagram: Questions about A or B, A and B Most textbook problems can be drawn all three ways. Reach for the tree when the question is conditional or the events happen one after another. #### Tree diagram questions, answered **What is a tree diagram in math and statistics?** It is a diagram that lists every outcome of a multi-step experiment as a path of branches, used to find the probability of combined events. Each fan of branches is one step; the number of paths is the number of outcomes (2 × 2 × 2 = 8 for three coins), and multiplying the probabilities along a path gives that outcome's probability. Counting problems use the same tree without the probabilities. **How do you make a tree diagram for a probability problem?** Draw one fan of branches per event, label each branch with its outcome and probability, then multiply along each path. Here you can type the problem as a sentence (a bag of 3 red and 2 blue, two draws without replacement) or type the branches as an indented list, one per line, with 3/5, 0.6 or 60% after each label; indent a line further to hang it from the line above. **How do you read the probabilities at the end of a tree diagram?** Each number at the end of a path is a joint probability: the chance that every event on that path happens, in that order. P(Red, Blue) = 3/5 × 2/4 = 3/10 means red first and blue second. To answer a question about an event, find every path that fits it and add their end values; all the end values together add to 1. **How does a tree diagram change without replacement?** Without replacement the second fan uses what is left after the first draw, so its fractions differ from branch to branch. From 3 red and 2 blue, the branches after a red are Red 2/4 and Blue 2/4, and after a blue Red 3/4 and Blue 1/4. With replacement every fan repeats 3/5 and 2/5, and the draws are independent. **Why must the branches from each point add up to 1?** Because the branches leaving one point are every possible result of that step, and exactly one of them happens. If the branches after Rain read Late 0.4 and On time 0.5, a result is missing or a number is wrong. This tool fills a single missing branch with the complement and draws any set that does not add to 1 exactly as you wrote it, without correcting it. **How do you find a conditional probability from a tree diagram?** Divide the path you want by the total of all paths that share the condition you are given. For the screening test, P(disease | test positive) = P(disease and positive) / P(test positive) = 1.8% / (1.8% + 4.9%) ≈ 26.9%. This is Bayes' theorem read off the tree, and it is why a positive result from a test for a rare condition is often a false alarm. **Should the fractions on a tree diagram be simplified?** The branches are usually left as written, and the end values are often shown both unsimplified and simplified. Keeping 6/20 next to 3/10 shows the common denominator, so the four outcomes visibly add to 20/20. Decimals and percentages work too; mix them only if your course does, because a tree in one form is easier to check. **Is a tree diagram the same as a family tree, a phylogenetic tree, a cladogram or a dichotomous key?** No: those four are different figures with their own conventions, and each has its own tool here. A family tree of inherited traits is a pedigree chart, an evolutionary tree with branch lengths is a phylogenetic tree, one built from shared derived traits is a cladogram, and an identification guide of paired choices is a dichotomous key. A tree diagram in maths is about outcomes and their probabilities. **Will the AI change the probabilities I give it?** No. Every branch value, product, sum and expected value is worked out in code before the image is drawn, and the model is told each one word for word. It is never asked to multiply 3/5 by 2/4. If your branches do not add to 1, the tree is drawn as you wrote it rather than quietly fixed, so check the numbers you type. **How should a tree diagram be captioned in a report or paper?** Say what the stages are, whether draws were replaced, and which numbers are conditional. For example: Figure 1. Probability tree for two draws without replacement from a bag of 3 red and 2 blue counters. Values on the branches are conditional probabilities; values at the ends are joint probabilities. For a decision tree, also state the payoff units and how expected values were rolled back. **Can an AI-drawn decision tree go into a journal article?** Often yes, because it is an explanatory image rather than a picture of your data, but the journal decides. Elsevier's generative AI policy for journals names decision trees among the explanatory images AI tools may help create, while images of primary research data may not be generated. Check your journal's own policy and say in the methods or legend how the figure was made. **How many outcomes can one tree diagram hold?** Up to four stages and 48 outcomes here, which covers two dice (36 outcomes) and four coin tosses (16). Past that a tree stops being readable on a page: use the counting principle or a table, or draw only the branches the question needs (for example, only the paths with at least one six). #### Sources - 3.5 Tree and Venn Diagrams — OpenStax Introductory Statistics 2e: https://openstax.org/books/introductory-statistics-2e/pages/3-5-tree-and-venn-diagrams - Introduction to Probability (Grinstead and Snell), tree diagrams and conditional probability — Dartmouth College: https://math.dartmouth.edu/~prob/prob/prob.pdf - Generative AI policies for journals — Elsevier: https://www.elsevier.com/about/policies-and-standards/generative-ai-policies-for-journals --- ### Radar Chart Maker: Spider Chart Generator from Your Data URL: https://scientificfigure.com/tools/radar-chart-maker Description: Free radar chart maker and spider graph generator: paste scores or upload Excel/CSV. Every vertex is placed from your numbers, on one scale or per-axis ranges. #### What is a radar chart? A radar chart plots several measurements of one subject on spokes that start from a common centre, then joins the points into a closed outline, so each subject becomes a shape. It is also called a spider chart, spider graph, web chart or radar graph, and in statistics a star plot. Profiles with similar shapes have similar strengths and weaknesses, which is what the chart is for: comparing a few subjects across the same set of measures. - Type the axes after Axes: and one line of scores per subject, paste a table from Excel, or attach a CSV, TSV or .xlsx file. - Scores typed in sentences are read either way round. An attached table with the measures down the side is turned when you write “rows are the axes”, or when its shape allows no other reading (more than six rows, or fewer than three columns). - Spoke angles, ring values and the position of every point along its spoke are computed in code before the image is drawn. - Axes measured in different units each get their own range, printed under the axis name; say “same scale” to keep one shared scale. - Up to six series and 3 to 12 axes on one chart; the Small multiples style gives each series a panel of its own. #### Where each point goes on a radar chart Each value becomes a distance from the centre along its own spoke: the fraction of the way from the axis minimum to the axis maximum. The spoke's angle comes from its position in the list, measured clockwise from 12 o'clock. r = (v − min) / (max − min), θᵢ = 360° × i / n #### Choosing the scale for a spider chart Where the centre sits and how far the outer ring reaches decide what the shapes say. - Shared, from zero — Centre and outer ring: 0 to a round number above the largest score | Use it when: Every axis is the same kind of score in the same unit | How to ask for it: Default when the axes are of similar size - Shared, stated — Centre and outer ring: The top of the scale you name; a rating scale starting at 1 is drawn from 0 | Use it when: Ratings on a fixed scale: 1 to 5, 0 to 10, 0 to 100 | How to ask for it: “on a 1–5 scale”, “out of 100” - Per axis, from zero — Centre and outer ring: 0 to a round number above each axis's largest value | Use it when: Axes in different units or of very different size | How to ask for it: “normalized”, “each axis on its own scale”, or automatic at about fivefold spread - Per axis, min–max — Centre and outer ring: Each axis's smallest to largest value | Use it when: Only the ranking within each axis matters | How to ask for it: “min–max normalized” A centre above zero exaggerates differences, so the per-axis range is always printed under the axis name and the legend or caption should say the axes were rescaled. #### Radar chart vs grouped bar chart vs heatmap A radar chart shows the overall shape of a few profiles; a grouped bar chart is better for reading exact differences; a heatmap is better once there are many subjects. - Best number of subjects — Radar chart: 1 to 3 on one chart, up to 6 as small multiples | Grouped bar chart: 2 to 4 series | Heatmap: Dozens of rows - Comparing one value between subjects — Radar chart: Hard: points sit on different spokes | Grouped bar chart: Easy: bars share one baseline | Heatmap: Approximate: colour steps - Seeing a whole profile at once — Radar chart: Yes, as a shape | Grouped bar chart: Spread across clusters | Heatmap: As a row of colours - Affected by axis order — Radar chart: Yes, the shape changes | Grouped bar chart: Only the reading order | Heatmap: Only the reading order - Axes in different units — Radar chart: Possible, with a range per axis | Grouped bar chart: Needs separate panels | Heatmap: Needs scaling, such as z-scores If the point of the figure is one exact difference, draw it with the bar graph maker; for many subjects or a matrix of scores, a heatmap with one row per subject. #### Radar chart questions, answered **How do I make a radar chart from my data?** Write the axes, then one line of scores per subject, and generate. For example: Axes: Bitterness, Acidity, Body. Blend A: 7.2, 4.1, 6.8. Blend B: 5.4, 6.6, 5.1. You can also paste the table from Excel or attach a CSV or .xlsx file with names in the first column. Add the scale if your scores have one, and pick a style. **Is a spider chart the same as a radar chart?** Yes. Spider chart, spider graph, web chart, radar graph and star plot all name the same figure: spokes from a common centre, one per variable, with each subject's values joined into a closed outline. Star plot is the statisticians' name: the NIST Engineering Statistics Handbook uses it, and typically draws one small star per observation. **How do I read a radar chart?** Read each spoke as its own axis: the further a point sits from the centre, the higher that score. Then compare outlines: a series bulging toward a spoke is strong on that measure. Check the scale before comparing spokes, because on a per-axis chart the same distance means different amounts on each axis. **Why does this radar chart maker not report the area of each polygon?** Because the area is not a property of the data. It is built from products of neighbouring values, so listing the same scores in a different axis order changes it, and it grows with the square of the scores: doubling every value makes the outline four times larger. Compare values spoke by spoke, or sum the scores if a total is what you need. **Does the order of the axes matter?** It changes the shape, not the values. Two strong measures placed next to each other make a broad lobe; placed apart they make two spikes. Put related measures side by side (all the physical tests, then all the cognitive ones) and keep the same order in every figure of the paper. The chart follows the order you type, starting at 12 o'clock and going clockwise. **When is a grouped bar chart or a heatmap better than a radar chart?** When readers must compare exact values, or when there are many subjects. Values on different spokes do not share a baseline, so a difference of 0.05 between two models is easier to judge in a grouped bar chart. With more than six subjects the outlines become unreadable, and a heatmap with subjects as rows shows the same table without the overlap. **Can each axis of a spider graph have its own scale?** Yes. Each axis then runs from its own minimum at the centre to its own maximum at the outer ring, and that range is printed under its label. This is needed when the axes are in different units, for example jump height in cm next to squat load in kg. It turns on automatically when the axes differ about fivefold or more; write “same scale” to keep one shared scale. **How is a radar chart in Excel different from this one?** Excel's radar chart draws every axis on one shared value scale, so axes in different units need rescaling in the sheet first. Here each axis can keep its own printed range, every point is placed from your numbers by code, a table with the measures in rows is turned for you, and the styles (outline, grayscale print, small multiples) are set for a figure panel. You can still attach the same .xlsx file. **Does the AI change or estimate my scores?** No. The scores, the ring values, every spoke angle and the distance of every point from the centre are calculated in code and given to the image model as fixed instructions. The model draws them and adds no number of its own. If your text holds no scores, nothing is calculated and the model works from your description. **How many axes and series can one radar chart have?** 3 to 12 axes and up to 6 series. Below three spokes there is no outline to draw, past twelve the labels crowd each other, and past six overlapping outlines no reader can follow one series around the chart. For more subjects, use small multiples across several figures or a heatmap. **What should the figure legend of a radar chart say?** State what each axis measures and its unit, the scale or the per-axis ranges, what each series is (and n, if the values are means), and the source of the scores. If the axes were rescaled, say how: for example “each axis scaled from 0 to its maximum”. A reader cannot recover any of this from the shape alone. #### Sources - Star Plot (Engineering Statistics Handbook, section 1.3.3.29) — NIST/SEMATECH: https://www.itl.nist.gov/div898/handbook/eda/section3/starplot.htm - The Radar chart and its caveats — Data to Viz: https://www.data-to-viz.com/caveat/spider.html --- ### Bell Curve Generator: Normal Distribution Graph Maker URL: https://scientificfigure.com/tools/bell-curve-generator Description: Free bell curve generator: set a mean and SD, shade any area and get a normal distribution graph with the exact probability, z-scores and 68-95-99.7 bands. #### What is a bell curve? A bell curve is the graph of a normal distribution: a symmetric, single-peaked curve centred on the mean, whose width is set by the standard deviation. The area under it between two values is the probability of a value landing between them, so shading an area answers a question such as what share of IQ scores fall below 85 (15.87%). The curve never touches the axis; one standard deviation either side of the mean it has dropped to 61% of its peak height, and that is exactly where it changes from bending down to bending out. - Type the parameters the way your course writes them: mean 100, SD 15; μ = 0, σ = 1; 72 ± 8; N(100, 15²). Paste a list of raw values instead and the curve is fitted with the sample mean x̄ and the sample SD s (n − 1). - Shaded areas are computed from the normal CDF before drawing and printed to four decimals: P(X < 85) = 0.1587 and P(85 < X < 115) = 0.6827 for mean 100, SD 15. - Percent cut-offs run backwards through the inverse CDF: the top 5% of IQ scores starts at 124.67, and the 90th percentile of the standard normal sits at z = 1.282. - The x axis spans μ − 4σ to μ + 4σ with a tick at every standard deviation (or at round numbers when a stated boundary falls between them); up to three curves can share it, each named in a legend. - Only the normal distribution is drawn, and no bars: for measured data with a normal curve on top, the histogram maker bins the sample on a density scale. #### The normal curve formula and the z-score The bell curve is the normal density f(x), and every probability read off it is an area under f, found by standardising with z = (x − μ)/σ. A z-score counts how many standard deviations a value sits from the mean, so one table of Φ answers questions on any normal scale, from IQ points to grams. f(x) = e^(−(x − μ)² / 2σ²) / (σ√(2π)) z = (x − μ) / σ P(X < x) = Φ(z) #### The empirical rule (68-95-99.7), exact values The rounded rule is what gets memorised; the exact areas are what a figure should print. Every row is computed from Φ, the standard normal CDF, and shown on the IQ scale for scale. - μ ± 1σ — Area inside: 68.27% | Area outside: 31.73% | IQ scale (mean 100, SD 15): 85 to 115 - μ ± 1.645σ — Area inside: 90.00% | Area outside: 10.00% | IQ scale (mean 100, SD 15): 75.3 to 124.7 - μ ± 1.96σ — Area inside: 95.00% | Area outside: 5.00% | IQ scale (mean 100, SD 15): 70.6 to 129.4 - μ ± 2σ — Area inside: 95.45% | Area outside: 4.55% | IQ scale (mean 100, SD 15): 70 to 130 - μ ± 2.576σ — Area inside: 99.00% | Area outside: 1.00% | IQ scale (mean 100, SD 15): 61.4 to 138.6 - μ ± 3σ — Area inside: 99.73% | Area outside: 0.27% | IQ scale (mean 100, SD 15): 55 to 145 95% of a normal distribution lies within 1.96 standard deviations of the mean, not 2. Two SD hold 95.45%; the 1.96 is the multiplier behind a 95% confidence interval and the critical value of a two-tailed test at α = 0.05. #### Where the normal curve is used Bell curves appear wherever a measurement is summarised by a mean and a standard deviation and a reader needs to see what that spread means. - Reference ranges in laboratory medicine: Many reference intervals are the central 95% of a healthy population, the mean ± 1.96 SD when the analyte is normally distributed; a shaded middle region shows which results get flagged as high or low. - Grading on a curve: Cut-offs set at fixed SD distances or at percentiles; the figure shows a class where each grade boundary sits and what share of students each band holds. - Hypothesis tests and confidence intervals: Rejection regions of a z test, a p value as the tail area beyond the observed z, a 95% interval as the middle 95%: the standard figures of an introductory statistics course. - Standardised test scores: IQ (mean 100, SD 15) and T-scores (mean 50, SD 10) are defined on a normal scale, so a percentile rank reads straight off the curve: an IQ of 130 is two SD up, above 97.72% of scores. #### Normal distribution FAQ **How do I make a bell curve?** Give a mean and a standard deviation, say which area to shade, and generate. For example: "IQ scores, mean 100, SD 15, shade above 130 and print the probability." The axis at each standard deviation, the curve's heights and P(X > 130) = 0.0228 are worked out before anything is drawn. In a spreadsheet the same figure means a column of x values, NORM.DIST for each, and a smoothed line chart. **What does the empirical rule (68-95-99.7) say?** About 68% of a normal distribution lies within one standard deviation of the mean, 95% within two and 99.7% within three. The exact areas are 68.27%, 95.45% and 99.73%. The rule holds only for normal data; for any distribution at all, Chebyshev's inequality guarantees just 75% within two standard deviations. **How do I find the probability of a shaded area under a bell curve?** Turn each boundary into a z-score, z = (x − μ)/σ, then take Φ(z) for the area below, 1 − Φ(z) for the area above, and the difference of two Φ values for the area between. With mean 100 and SD 15: P(X < 85) = Φ(−1) = 0.1587, P(X > 115) = 0.1587, P(85 < X < 115) = 0.6827. This page is a figure maker rather than a normal distribution calculator, but it runs exactly that arithmetic and prints the result on the shaded region. **What is a z-score on a bell curve?** The number of standard deviations a value lies from the mean, z = (x − μ)/σ. A height of 176 cm, with mean 162 cm and SD 7 cm, has z = 2.00, and 97.72% of the distribution lies below it. On a standard normal curve the x axis is the z scale itself, so the critical values ±1.96 can be marked directly. **How do I shade the top 5% or mark a percentile?** Ask for it as a percent and the cut-off is found with the inverse normal CDF. The top 5% of IQ scores starts at 124.67 (z = 1.645), the bottom 10% ends at 80.78 (z = −1.282), and the 90th percentile of daily steps with mean 8000 and SD 2000 is 10,563. **Should I use a bell curve or a histogram?** A histogram shows data you measured; a bell curve shows a model, the normal distribution with a stated mean and SD. To check whether a sample looks normal, draw its histogram with a normal curve overlay on a density scale. Draw a bare bell curve to teach a distribution, mark cut-offs or show a probability. **What should a figure legend for a bell curve say?** Name the distribution, its parameters and what the shading means, for example: "Normal distribution with mean 100 and SD 15; the shaded area, P(X < 85) = 0.1587, is the proportion of scores below 85." For a fitted curve, give n, x̄ and s and say the curve is a normal fit rather than the data. When μ and σ come from a published population, cite it. **Can two normal curves be compared on one graph?** Yes: up to three curves share one axis, each in its own colour and named once in the legend. The point where two curves with equal SDs cross is halfway between their means; with unequal SDs they cross twice, once on each side of the narrower curve's peak. Ask for the overlap, or for Cohen's d, and those are printed too. **Does the AI change my mean, SD or probabilities?** No. Every tick, the curve's height at seventeen points, each boundary's z-score and every shaded probability are computed from your parameters first, and the image model is told to place them, not to work them out. A generic request with no parameters is drawn as the standard normal (mean 0, SD 1); IQ and T-score figures use the scales' defined values. **Is my data normal enough to draw as a bell curve?** A normal curve suits a variable that is roughly symmetric around one peak; check with a histogram or a normal Q-Q plot first. Right-skewed measurements such as reaction times, incomes or antibody titres misrepresent badly under a normal curve and are better shown as they are, or after a log transform. #### Sources - 1.3.6.6.1. Normal Distribution — NIST/SEMATECH, e-Handbook of Statistical Methods: https://www.itl.nist.gov/div898/handbook/eda/section3/eda3661.htm - 6.1 The Standard Normal Distribution — OpenStax, Introductory Statistics 2e: https://openstax.org/books/introductory-statistics-2e/pages/6-1-the-standard-normal-distribution --- ### Scatter Plot Maker with Line of Best Fit, r and R² URL: https://scientificfigure.com/tools/scatter-plot-maker Description: Scatter plot maker and generator: paste x,y pairs or upload Excel/CSV, get the line of best fit, r, R² and p computed exactly, drawn in journal style. #### What is a scatter plot? A scatter plot (scatter graph) shows how two numeric variables vary together: every observation is one marker, placed at its x value across and its y value up. The usual convention puts the response on the y axis and the variable suspected of driving it on the x axis. The cloud of points shows the direction of the relationship, how tight it is, whether it is straight or curved, and which observations sit apart from the rest. A straight line fitted by least squares, the line of best fit, summarises a linear trend, and Pearson's r with R² puts a number on how closely the points follow it. A scatter plot shows association only: it cannot show which variable causes the other. - Type pairs in brackets, Control: (1, 2.1), (2, 3.9)…, or give two lists of equal length. Spreadsheets work too: up to three .csv, .tsv or .xlsx files, x in one column and each series' y in the next. - The fitted line, Pearson r, R², the two-sided p and Spearman ρ are computed in code from your pairs and handed to the image model with every point's coordinates; the model only places them. - Up to four groups, each with its own marker shape, its own line and its own r. Write "one line for all groups" for a single pooled fit. - Above 300 pairs the figure draws a random 300 of them and says so; the statistics and the line still come from every pair. - Options are written in plain words: a 1:1 line, log-log axes, a residual plot, a 95% confidence band, the regression equation, axes from zero, point labels. #### The line of best fit, r and R²: the formulas Least squares picks the slope b and intercept a that make the sum of squared vertical distances from the points to the line as small as possible; r is the same cross-product scaled by both spreads. With Sxx = Σ(x − x̄)², Syy = Σ(y − ȳ)² and Sxy = Σ(x − x̄)(y − ȳ), the formulas below are the ones this tool computes, and the test of r on the right is the one that gives the p value. b = Sxy ÷ Sxx a = ȳ − b·x̄ r = Sxy ÷ √(Sxx·Syy) R² = r² t = r·√((n − 2) ÷ (1 − r²)), df = n − 2 #### Reading a correlation from a scatter plot What the cloud of points looks like, the r it usually comes with, and what to check before reporting it. The cut-offs are a rough guide, not a rule. - Lie almost on one rising or falling line — Typical r: Close to +1 or −1 | Check before you report it: Whether the agreement is real or built in, such as a variable plotted against a sum that contains it - Form a clear tilted ellipse — Typical r: Around ±0.5 to ±0.8 | Check before you report it: The p value with n, and the residual plot for curvature - Drift weakly with a lot of scatter — Typical r: Around ±0.1 to ±0.3 | Check before you report it: Whether a large n is making a small effect significant - Form a round or shapeless cloud — Typical r: Near 0 | Check before you report it: That the range of x is not too narrow to show a trend - Follow a curve, an arch or a U shape — Typical r: Can be near 0 despite a strong relationship | Check before you report it: A log axis, Spearman ρ, or a curved model instead of a straight line - Sit in a cloud with one point far away — Typical r: Pulled toward ±1 or toward 0 by that one point | Check before you report it: r with and without the point, and Spearman ρ, which ranks the values The same r can come from very different scatter plots. Anscombe's four datasets share their means, variances, r and fitted line, yet one is a straight trend, one a curve, one a line with an outlier and one a vertical stack with a single distant point. That is why the plot is shown, not only the coefficient. #### Scatter plot vs line graph A scatter plot shows unordered pairs and the trend through them; a line graph joins points in the order of x, usually time or dose, to show a change. Choose by whether connecting neighbouring points means anything. - Each point is — Scatter plot: One subject, sample or observation | Line graph: A value (often a mean) at one x position - Points joined? — Scatter plot: Never; the order of the rows is meaningless | Line graph: Yes, in order of x - Many y values at one x — Scatter plot: Normal, they stack vertically | Line graph: Usually summarised as a mean with error bars - The line shows — Scatter plot: A fitted trend through the whole cloud | Line graph: The path from one x value to the next - Typical figure — Scatter plot: Expression of gene A against gene B in 40 tumours | Line graph: Tumour volume over 21 days in treated and control mice For measurements over time in the same subjects, use the line graph maker. For the pairwise correlations among many variables at once, a correlation matrix in the heatmap generator fits more than a grid of scatter plots. #### Scatter plot questions, answered **How do you make a scatter plot?** Put the response variable on the y axis and the explanatory one on the x axis, then place one marker per observation at its pair of values. Choose axis ranges a little wider than the data, label both axes with units, and add a fitted line only if a straight-line trend is what you want to report. Here you type the pairs or attach the spreadsheet, and the axes, line and statistics are computed before the figure is drawn. **Which variable goes on the x axis of a scatter plot?** The explanatory (independent) variable goes on x, the response on y. Dose, time, concentration or body size usually go across; what you measured in response goes up. When neither causes the other, as with two genes' expression, put the one you would predict from on x, since the least-squares line predicts y from x. **What is the difference between r and R² on a scatter plot?** r is the correlation coefficient, from −1 to +1, and carries the direction; R² is r squared, from 0 to 1, and is the proportion of the variance in y explained by the line. r = −0.7 and r = +0.7 both give R² = 0.49. Report r for a correlation and R² for how well a regression line fits; journals in many fields expect r with its p and n. **Is a trendline the same as a line of best fit?** For a straight line, yes: both are the ordinary least-squares regression of y on x. Spreadsheet software calls it a linear trendline; statistics texts call it the least-squares or regression line. This tool always fits that line, on log values when an axis is logarithmic, and states its equation when you ask for it. **What does the p value next to r mean?** It is the probability of a correlation at least this far from zero if the true correlation were zero, from a t test with n − 2 degrees of freedom. A small p says the trend is unlikely to be chance; it says nothing about how strong the trend is. With 500 points, r = 0.1 gives p ≈ 0.025, so report r and n beside p. **When should I use Spearman's ρ instead of Pearson's r?** Use Spearman when the relationship rises or falls steadily but not in a straight line, when the data are ranks or scores, or when an outlier dominates r. Spearman's ρ is Pearson's r computed on the ranks of x and of y, so it measures any monotonic trend and one extreme value counts only as the top rank. Write "Spearman" and both coefficients are printed. **Should the axes of a scatter plot start at zero?** No: unlike a bar chart, a scatter plot's axes should span the data, not the origin. Forcing zero squeezes the cloud into a corner and hides the trend. Include zero only when it means something for the figure, such as a calibration curve's blank or an intercept you want readers to see; write "axes from zero" to get it. **What is the difference between a scatter plot, an XY graph and a dot plot?** An XY graph is any chart drawn on two numeric axes; a scatter plot is the XY graph of unconnected points. A dot plot is different again: one numeric axis, with each observation a dot stacked along it per category or value, so it shows a distribution rather than a relationship between two variables. **How do I show the correlations among many variables?** Six or more variables give at least 15 pairs, too many for separate scatter plots in a paper, so the usual figure is a correlation matrix drawn as a heatmap. Make it in the heatmap generator and keep a scatter plot here for the one or two pairs the paper is about, where readers need to see the points. **How should a scatter plot's figure legend be written?** Say what each point is, what the line is and which statistic was tested, with n. For example: "Each point is one tree species (n = 14). Line, least-squares regression; Pearson r = 0.93, two-sided p < 0.001." Name the groups, state any log scale, and say if the drawn points are a subset of a larger sample. **Does the AI change my numbers?** No: every point's coordinates, the axis ticks, the fitted line's two end points and the printed r, R², p and n are calculated in code and stated to the image model, which only places them. It is told never to move, add or drop a point or refit the line. Above 300 pairs the drawn cloud is a random 300, while every statistic still uses all of them. #### Sources - 1.3.3.26. Scatter Plot — NIST/SEMATECH e-Handbook of Statistical Methods: https://www.itl.nist.gov/div898/handbook/eda/section3/scatterp.htm - 12.4 Testing the Significance of the Correlation Coefficient — OpenStax, Introductory Statistics 2e: https://openstax.org/books/introductory-statistics-2e/pages/12-4-testing-the-significance-of-the-correlation-coefficient --- ### Coagulation Cascade Diagram — Labeled Clotting Cascade, Free URL: https://scientificfigure.com/tools/coagulation-cascade-diagram Description: Free coagulation cascade diagram: intrinsic, extrinsic and common pathways from factor XII and tissue factor to fibrin. Labeled clotting cascade with PT/aPTT. #### What is the coagulation cascade? The coagulation cascade is the chain of enzyme reactions in which clotting factors — plasma proteins numbered I to XIII — activate one another in turn, from factor XII in the intrinsic pathway or tissue factor with factor VII in the extrinsic pathway, through factor X and thrombin, until soluble fibrinogen becomes a cross-linked fibrin clot. An activated factor carries the suffix “a”: factor X becomes Xa. - Two starting arms meet at factor X. In the extrinsic (tissue factor) pathway, injury exposes tissue factor, which binds factor VIIa; in the intrinsic (contact activation) pathway, XIIa activates XI and XIa activates IX, and IXa with its cofactor VIIIa activates factor X. From Xa onward the steps are shared: the common pathway. - Thrombin is the enzyme that makes the clot. Factor Xa with its cofactor Va on a phospholipid surface forms prothrombinase, which converts prothrombin (II) into thrombin (IIa); thrombin cuts fibrinogen (I) into fibrin and activates factor XIII, and XIIIa cross-links the fibrin into a stable clot. - Calcium is factor IV. Ca²⁺ is needed in most thrombin-generating reactions, which is why citrate and EDTA keep a blood sample liquid; the vitamin K–dependent factors II, VII, IX and X bind phospholipid surfaces through calcium bridges. - There is no factor VI. The factors were numbered I to XIII in order of discovery; factor VI turned out to be the same as factor V, and the number was left empty rather than renumbering the rest. - In the body the cascade runs as the cell-based model. Initiation on tissue factor–bearing cells makes a little thrombin; amplification uses it to activate platelets and factors V, VIII and XI; propagation on the platelet surface produces a burst of thrombin. The intrinsic/extrinsic split still explains the PT and aPTT tests. #### Clotting factors in the coagulation cascade The factors a labeled coagulation cascade diagram is normally expected to show, their names, what each one does and the pathway it belongs to. This is the default content unless you ask for something else. - XII — Name: Hageman factor | What it does: Activated to XIIa by contact with a negatively charged surface; activates factor XI | Pathway: Intrinsic - XI — Name: Plasma thromboplastin antecedent | What it does: Activated to XIa; activates factor IX. Deficiency causes hemophilia C | Pathway: Intrinsic - IX — Name: Christmas factor | What it does: Activated to IXa, the enzyme of the IXa–VIIIa complex that activates factor X. Deficiency causes hemophilia B | Pathway: Intrinsic - VIII — Name: Antihemophilic factor | What it does: Activated to VIIIa, the cofactor of IXa. Deficiency causes hemophilia A | Pathway: Intrinsic - III — Name: Tissue factor | What it does: Exposed on cells around the vessel wall after injury; binds factor VIIa | Pathway: Extrinsic - VII — Name: Proconvertin | What it does: Forms the tissue factor–VIIa complex, which activates factor X | Pathway: Extrinsic - X — Name: Stuart–Prower factor | What it does: Activated to Xa, the enzyme of prothrombinase | Pathway: Common - V — Name: Proaccelerin | What it does: Activated to Va, the cofactor of Xa in prothrombinase | Pathway: Common - II — Name: Prothrombin | What it does: Converted by prothrombinase into thrombin (IIa) | Pathway: Common - I — Name: Fibrinogen | What it does: Cut by thrombin into fibrin strands | Pathway: Common - XIII — Name: Fibrin-stabilizing factor | What it does: Activated by thrombin to XIIIa, which cross-links fibrin | Pathway: Common - IV — Name: Calcium ions (Ca²⁺) | What it does: Needed in most steps; bridges factors to the phospholipid surface | Pathway: All three Factors II, VII, IX and X are vitamin K–dependent, which is why warfarin, a vitamin K antagonist, lowers all four. Name the factors you need and only those are drawn. #### Intrinsic vs extrinsic pathway: what is the difference? The extrinsic pathway starts outside the blood, when injury exposes tissue factor, which binds factor VIIa; the intrinsic pathway starts inside it, when factor XII meets a negatively charged surface and activates XI, then IX, with VIIIa as cofactor. Both end by activating factor X, where the common pathway begins. - Other name — Intrinsic pathway: Contact activation pathway | Extrinsic pathway: Tissue factor pathway - Trigger — Intrinsic pathway: Factor XII contacting a negatively charged surface, such as glass in a test tube | Extrinsic pathway: Tissue factor exposed by damage to the vessel wall - Factors — Intrinsic pathway: XII, XI, IX and VIII | Extrinsic pathway: Tissue factor (III) and VII - Complex that activates X — Intrinsic pathway: IXa with VIIIa on a phospholipid surface, with Ca²⁺ | Extrinsic pathway: Tissue factor–VIIa, with Ca²⁺ - Speed — Intrinsic pathway: A few minutes | Extrinsic pathway: Seconds - Lab test — Intrinsic pathway: aPTT (activated partial thromboplastin time) | Extrinsic pathway: PT (prothrombin time), reported as the INR - Inherited deficiency — Intrinsic pathway: Hemophilia A (VIII), B (IX) and C (XI) | Extrinsic pathway: Factor VII deficiency, which is rare - Drug usually monitored — Intrinsic pathway: Unfractionated heparin | Extrinsic pathway: Warfarin Factor XII is not needed for clotting in the body: people born without it have no bleeding problem, although it starts clotting in a glass test tube. That is one reason the cell-based model has replaced the two-arm scheme for describing clotting in vivo. #### Where are coagulation cascade diagrams used? Coagulation cascade diagrams are used mostly in medical, nursing and pharmacy teaching — physiology, hematology and pharmacology — and as figures in hemostasis and thrombosis papers. The version changes with the reader: six boxes for a first lecture, every factor and cofactor for an exam, the cell-based model for research. - Medical and nursing school: Physiology and hematology lectures and exam revision, where the classical cascade with its factor numbers and activated forms is expected by heart, often as a blank diagram to fill in. - Pharmacology: Showing where anticoagulants act: warfarin lowering the vitamin K–dependent factors II, VII, IX and X, heparin boosting antithrombin against thrombin and Xa. - Laboratory medicine: Explaining a prolonged PT or aPTT: which arm of the cascade each test covers and which factor deficiencies or drugs lengthen it. - Research figures and posters: Hemostasis and thrombosis papers, reviews and conference posters, from a simple overview to the initiation, amplification and propagation phases of the cell-based model. #### Common questions about the coagulation cascade **How do I draw a coagulation cascade diagram?** Draw the intrinsic pathway (XII → XI → IX, with VIIIa) on one side and the extrinsic pathway (tissue factor with VIIa) on the other, join both arrows at factor X, then run the common pathway down the middle: Xa with Va turns prothrombin into thrombin, thrombin turns fibrinogen into fibrin, and XIIIa cross-links it. With this maker you describe the version you need and the cascade is drawn top to bottom in that order. **Is the clotting cascade the same as the coagulation cascade?** Yes. Clotting cascade, coagulation cascade and blood coagulation pathway all name the same series of factor activations. Ask for a clotting cascade diagram and you get the same figure. **What are the three pathways of the coagulation cascade?** The intrinsic pathway (factors XII, XI, IX and VIII), the extrinsic pathway (tissue factor and factor VII) and the common pathway (factors X, V, II, I and XIII). The first two each activate factor X; everything after that is shared. **Which factors are in the common pathway?** Factor X, its cofactor V, prothrombin (II), fibrinogen (I) and factor XIII, with calcium throughout. Xa and Va form prothrombinase, which makes thrombin; thrombin makes fibrin and activates XIII, which cross-links it. **What is the difference between PT and aPTT?** The PT (prothrombin time, reported as the INR) tests the extrinsic and common pathways; the aPTT tests the intrinsic and common pathways. A long PT with a normal aPTT points to factor VII; a long aPTT with a normal PT points to factor VIII, IX or XI, as in hemophilia; both long suggests the common pathway, liver disease or vitamin K deficiency. **Where do warfarin and heparin act on the coagulation cascade?** Warfarin is a vitamin K antagonist: the liver can no longer make working factors II, VII, IX and X, and it is monitored with the PT/INR. Heparin boosts antithrombin, which then inactivates thrombin and factor Xa; unfractionated heparin is monitored with the aPTT. Ask for the cascade with the drug sites marked and each is drawn with an inhibition bar on its target. **What is the cell-based model of coagulation?** It describes clotting as three overlapping phases on cell surfaces: initiation, where tissue factor–VIIa on tissue factor–bearing cells makes a small amount of thrombin; amplification, where that thrombin activates platelets and factors V, VIII and XI; and propagation, where tenase and prothrombinase on activated platelets make a burst of thrombin. Textbooks still teach the classical cascade because it explains the PT and aPTT. **Why is there no factor VI?** Because factor VI turned out to be the same as factor V. The factors are numbered by order of discovery, so VI was kept as an empty place rather than renumbering VII to XIII. **Which clotting factors need vitamin K?** Factors II, VII, IX and X, plus the anticoagulant proteins C and S. They are made in the liver and need vitamin K to become functional, which is why vitamin K deficiency and warfarin both prolong the PT. **What does a D-dimer test measure?** D-dimer is a fragment of cross-linked fibrin, released when plasmin breaks a clot down, so it shows that a clot has formed and been lysed somewhere. A normal value helps rule out deep vein thrombosis and pulmonary embolism when clinical probability is low; a raised value is not specific, since surgery, infection, pregnancy, cancer and age all increase it. #### Sources - Hemostasis — Anatomy and Physiology 2e, section 18.5 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/18-5-hemostasis - Overview of Hemostasis — MSD Manual Professional Edition: https://www.msdmanuals.com/professional/hematology/hemostasis/overview-of-hemostasis - Excessive Bleeding (PT and aPTT screening tests) — MSD Manual Professional Edition: https://www.msdmanuals.com/professional/hematology/hemostasis/excessive-bleeding - Coagulation pathway (R-HSA-9769740) — Reactome: https://reactome.org/content/detail/R-HSA-9769740 --- ### RAAS Diagram — Renin–Angiotensin–Aldosterone System, Free URL: https://scientificfigure.com/tools/raas-diagram Description: Free renin–angiotensin–aldosterone system diagram: renin, angiotensin I and II, ACE, aldosterone, ADH, where ACE inhibitors and ARBs act. Labeled RAAS pathway. #### What is the renin–angiotensin–aldosterone system? The renin–angiotensin–aldosterone system (RAAS) is the hormone cascade that raises blood pressure and blood volume: when pressure falls, kidney juxtaglomerular cells release renin, which turns angiotensinogen from the liver into angiotensin I; angiotensin-converting enzyme (ACE), mainly in the lungs, turns that into angiotensin II, which constricts arterioles and releases aldosterone and ADH. Aldosterone makes the kidney keep Na⁺ and, with it, water. - Three signals release renin. Low pressure in the afferent arteriole, less NaCl reaching the macula densa, and sympathetic nerve stimulation through β-receptors all make juxtaglomerular cells secrete renin; circulating angiotensin II feeds back to suppress it. - Renin and ACE are the two cutting steps. Renin cleaves angiotensinogen into the 10-amino-acid angiotensin I; ACE removes two more amino acids to give the active 8-amino-acid angiotensin II. - Angiotensin II acts mainly through the AT1 receptor. Vasoconstriction, Na⁺ reabsorption and aldosterone secretion all run through AT1 — the receptor that ARBs block. Angiotensin II also triggers thirst, ADH release and sympathetic discharge. - The fast arm and the slow arm. Angiotensin II raises pressure at once by vasoconstriction; aldosterone raises it more slowly by making the distal tubule and collecting duct reabsorb Na⁺ (water follows) and excrete K⁺. - Four drug classes block the chain. Direct renin inhibitors (aliskiren) act on renin, ACE inhibitors (lisinopril) on ACE, angiotensin II receptor blockers (losartan) on the AT1 receptor and aldosterone receptor antagonists (spironolactone) on the aldosterone receptor; an ACE inhibitor and an ARB should not be combined. #### Components of the renin–angiotensin–aldosterone system The steps a labeled RAAS diagram is normally expected to show, where each one is made, what it does and what comes next. This is the default content unless you ask for something else. - Macula densa — Made in or released from: Distal tubule, at the juxtaglomerular apparatus | What it does: Senses less NaCl in the tubular fluid | Next step: Signals the juxtaglomerular cells - Renin — Made in or released from: Juxtaglomerular cells of the afferent arteriole | What it does: Enzyme that cleaves angiotensinogen | Next step: Angiotensin I - Angiotensinogen — Made in or released from: Liver | What it does: Inactive precursor circulating in plasma | Next step: Cut by renin - Angiotensin I — Made in or released from: Blood plasma | What it does: Inactive 10-amino-acid peptide | Next step: Converted by ACE - ACE (angiotensin-converting enzyme) — Made in or released from: Endothelium, mainly in the lungs | What it does: Converts angiotensin I into angiotensin II | Next step: Angiotensin II - Angiotensin II — Made in or released from: Blood plasma | What it does: Constricts arterioles; releases aldosterone and ADH; triggers thirst and sympathetic discharge | Next step: AT1 receptors on vessels, adrenal cortex and brain - Aldosterone — Made in or released from: Adrenal cortex | What it does: Na⁺ reabsorption (water follows) and K⁺ excretion in the distal tubule and collecting duct | Next step: Blood volume rises - ADH (vasopressin) — Made in or released from: Posterior pituitary | What it does: Water reabsorption in the collecting duct; constricts peripheral vessels | Next step: Blood volume rises - Natriuretic peptides (ANP, BNP) — Made in or released from: Heart atria and ventricles | What it does: Counter the RAAS: suppress renin, aldosterone and ADH | Next step: Blood pressure falls RAS and RAAS name the same system: renin–angiotensin system (RAS) stresses the renin → angiotensin steps, RAAS names aldosterone as well. Name the steps you need and only those are drawn. #### ACE inhibitors vs ARBs: where does each act in the RAAS? ACE inhibitors block the enzyme that turns angiotensin I into angiotensin II; angiotensin II receptor blockers (ARBs) let angiotensin II form but stop it acting on its AT1 receptor. Both lower blood pressure and both are first-line choices for hypertension, but they are not given together. - Examples — ACE inhibitor: Lisinopril, ramipril | ARB: Losartan - Step blocked — ACE inhibitor: Angiotensin I → angiotensin II (ACE) | ARB: Angiotensin II → AT1 receptor - Where to draw the bar — ACE inhibitor: On the ACE arrow | ARB: Between angiotensin II and its effects - Effect on the cascade — ACE inhibitor: Less angiotensin II is made | ARB: Angiotensin II is made but cannot act through AT1 - Why one is swapped for the other — ACE inhibitor: Cough or angioedema can make it intolerable | ARB: Used when an ACE inhibitor causes cough or angioedema - In pregnancy — ACE inhibitor: Contraindicated | ARB: Contraindicated - Together — ACE inhibitor: Not combined with an ARB | ARB: Not combined with an ACE inhibitor Two more drug classes act on the same chain: direct renin inhibitors such as aliskiren block renin at the top, and aldosterone receptor antagonists such as spironolactone block aldosterone at the bottom. #### Where are RAAS diagrams used? RAAS diagrams are used mostly in physiology, nursing and pharmacology teaching — blood pressure control, kidney function, antihypertensive drugs — and as figures in cardiovascular and renal papers. The level of detail follows the reader: six boxes for a first lesson, every organ, receptor and drug target for a pharmacology exam. - Physiology and nursing courses: Blood pressure regulation and kidney function units, where the RAAS is drawn from the trigger to aldosterone, often as a blank diagram to complete. - Pharmacology: Showing where the antihypertensive classes act: direct renin inhibitors, ACE inhibitors, ARBs and aldosterone receptor antagonists, each as an inhibition bar on its step. - Clinical teaching: Explaining how the body answers blood loss, dehydration or heart failure, why blocking it lowers blood pressure, and why spironolactone spares potassium. - Research figures and posters: Cardiovascular, renal and endocrine papers, reviews and posters, from the classical cascade to the ACE2 and angiotensin-(1–7) branch. #### Common questions about the RAAS **How do I draw a RAAS diagram?** Start at the top with the trigger (low blood pressure), then draw the kidney releasing renin, renin turning angiotensinogen from the liver into angiotensin I, ACE in the lungs making angiotensin II, and angiotensin II fanning out to vasoconstriction, aldosterone, ADH and thirst, all converging on a rise in blood pressure. With this maker you describe the version you need and it is drawn top to bottom in that order. **What are the steps of the renin–angiotensin–aldosterone system?** Low pressure → juxtaglomerular cells release renin → renin converts angiotensinogen to angiotensin I → ACE converts angiotensin I to angiotensin II → angiotensin II constricts arterioles and releases aldosterone and ADH → the kidney keeps Na⁺ and water → blood volume and pressure rise. Rising angiotensin II then suppresses renin. **What triggers renin release?** A fall in pressure sensed in the afferent arteriole, less NaCl reaching the macula densa, and sympathetic stimulation through β-receptors. Angiotensin II itself inhibits renin release, closing the loop. **Where is ACE found?** Mainly on the endothelial cells of the lungs, which is where most angiotensin I is converted, but also in the kidneys and the brain. Most diagrams draw the lungs beside the ACE step. **What does angiotensin II do?** It constricts arterioles, stimulates the adrenal cortex to release aldosterone, releases ADH from the posterior pituitary, triggers thirst and increases sympathetic discharge. Together these raise blood volume and blood pressure. **What does aldosterone do in the RAAS?** Aldosterone makes the distal tubule and collecting duct reabsorb Na⁺ and excrete K⁺; water follows the sodium, so blood volume and pressure rise. It is the slow arm of the system, where angiotensin II vasoconstriction is the fast one. **Where do ACE inhibitors and ARBs act?** ACE inhibitors (lisinopril, ramipril) block the conversion of angiotensin I to angiotensin II; ARBs (losartan) block angiotensin II at its AT1 receptor. Direct renin inhibitors (aliskiren) act one step higher and aldosterone receptor antagonists (spironolactone) at the end of the chain. **How is the RAAS switched off?** By negative feedback: angiotensin II inhibits renin release, and as pressure and NaCl delivery recover the triggers disappear. Natriuretic peptides from the stretched heart also suppress renin, aldosterone and ADH. **Is renin a hormone or an enzyme?** Renin is an enzyme — a protease that cleaves angiotensinogen — although some sources call it a hormone because it is secreted into the blood and drives a hormone system. Diagrams usually draw it as the enzyme beside the angiotensinogen → angiotensin I arrow. **Why can ACE inhibitors and ARBs raise potassium and creatinine?** Less angiotensin II action means less aldosterone, so the collecting duct secretes less K⁺; and the efferent arteriole relaxes, so glomerular pressure and GFR fall. A small rise in creatinine after starting is expected; potassium and creatinine are checked within the first weeks, and the risk of hyperkalemia is highest with chronic kidney disease or alongside a mineralocorticoid receptor antagonist. #### Sources - Homeostatic Regulation of the Vascular System — Anatomy and Physiology 2e, section 20.4 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/20-4-homeostatic-regulation-of-the-vascular-system - Endocrine Regulation of Kidney Function — Anatomy and Physiology 2e, section 25.8 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/25-8-endocrine-regulation-of-kidney-function - Hypertension — MSD Manual Professional Edition: https://www.msdmanuals.com/professional/cardiovascular-disorders/hypertension/hypertension - Metabolism of Angiotensinogen to Angiotensins (R-HSA-2022377) — Reactome: https://reactome.org/content/detail/R-HSA-2022377 --- ### Cell Cycle Diagram — Labeled & Blank, Phases & Checkpoints URL: https://scientificfigure.com/tools/cell-cycle-diagram Description: Free cell cycle diagram, labeled and blank: G1, S, G2 and M phases, G0, the three checkpoints and the cyclin–CDK pairs that drive each transition. #### What is the cell cycle? The cell cycle is the ordered series of events in which a eukaryotic cell grows, copies its DNA and divides into two identical daughter cells: interphase — G1, S and G2 — followed by the mitotic (M) phase of mitosis and cytokinesis, with checkpoints at G1/S, G2/M and metaphase that halt the cycle until conditions are right. Cyclin–CDK complexes drive the cell from one phase to the next. - Interphase takes almost all of the time. In rapidly dividing human cells with a 24-hour cycle, G1 lasts about 9 hours, S about 10 hours, G2 about 4.5 hours and M only about half an hour — which is why a correct diagram draws M as a thin slice. - DNA is copied once, in S phase. Each chromosome is replicated into two sister chromatids joined at the centromere, and the centrosome is duplicated too; G1 and G2 are growth and preparation gaps on either side. - Three checkpoints guard the cycle. The G1 checkpoint (restriction point) checks size, reserves, growth signals and DNA damage; the G2/M checkpoint checks that the DNA is fully replicated and undamaged; the spindle checkpoint holds anaphase until every kinetochore is attached to spindle fibers from opposite poles. - Cyclins rise and fall; CDKs stay. CDK levels stay fairly constant while cyclins come and go: cyclin D–CDK4/6 in early G1, cyclin E–CDK2 at the G1/S transition, cyclin A–CDK2 during S phase and cyclin B–CDK1 at the G2/M transition. - Cells can leave the cycle into G0. Quiescent cells wait in G0 until a signal returns them to G1; cells that never or rarely divide, such as mature cardiac muscle and nerve cells, stay in G0 permanently. #### Phases of the cell cycle The phases and checkpoints a labeled cell cycle diagram is normally expected to show, what happens in each and what drives or checks it. This is the default content unless you ask for something else. - G0 — Part of: Outside the cycle | What happens: Quiescent: the cell carries out its job without preparing to divide | Driven or checked by: Growth signals return it to G1 - G1 (first gap) — Part of: Interphase | What happens: The cell grows and gathers building blocks and energy for DNA replication | Driven or checked by: Cyclin D–CDK4/6 - G1/S checkpoint — Part of: End of G1 | What happens: Checks size, reserves, growth signals and DNA damage; the restriction point | Driven or checked by: p53, p21, Rb; cyclin E–CDK2 lets the cell pass - S (synthesis) — Part of: Interphase | What happens: DNA is replicated into sister chromatids; the centrosome is duplicated | Driven or checked by: Cyclin A–CDK2 - G2 (second gap) — Part of: Interphase | What happens: The cell makes the proteins needed for mitosis | Driven or checked by: Cyclin B–CDK1 builds up - G2/M checkpoint — Part of: End of G2 | What happens: Checks that all DNA is replicated and undamaged | Driven or checked by: Cyclin B–CDK1 triggers entry into mitosis - Prophase — Part of: M phase (mitosis) | What happens: Chromosomes condense; the spindle starts to form | Driven or checked by: Cyclin B–CDK1 - Prometaphase — Part of: M phase (mitosis) | What happens: The nuclear envelope breaks down; kinetochores attach to spindle fibers | Driven or checked by: Cyclin B–CDK1 - Metaphase — Part of: M phase (mitosis) | What happens: Chromosomes line up at the metaphase plate | Driven or checked by: Spindle checkpoint - Anaphase — Part of: M phase (mitosis) | What happens: Sister chromatids separate and move to opposite poles | Driven or checked by: APC/C, once the spindle checkpoint is satisfied - Telophase — Part of: M phase (mitosis) | What happens: Nuclear envelopes re-form; chromosomes decondense | Driven or checked by: — - Cytokinesis — Part of: M phase | What happens: The cytoplasm divides: a cleavage furrow in animal cells, a cell plate in plant cells | Driven or checked by: — Arcs follow the timing: in a 24-hour human cell, G1 ≈ 9 h, S ≈ 10 h, G2 ≈ 4.5 h, M ≈ 0.5 h. Timings vary between cell types, so ask for the numbers your course uses and they are drawn instead. #### Cell cycle vs mitosis: what is the difference? The cell cycle is the whole life of a dividing cell — growth, DNA replication and division — while mitosis is only the division of the nucleus inside its M phase. Mitosis takes about half an hour of a 24-hour human cell cycle; interphase takes the rest. - What it covers — Cell cycle: Interphase (G1, S, G2) and M phase | Mitosis: Nuclear division within M phase - DNA replication — Cell cycle: Yes, in S phase | Mitosis: No; the DNA is already copied - Stages — Cell cycle: G1, S, G2, M (and G0 outside) | Mitosis: Prophase, prometaphase, metaphase, anaphase, telophase - Share of a 24-hour human cycle — Cell cycle: All 24 hours | Mitosis: About 30 minutes - Chromosomes — Cell cycle: Mostly semi-condensed chromatin | Mitosis: Condensed and visible under a light microscope - Checkpoints — Cell cycle: G1/S, G2/M and spindle | Mitosis: The spindle checkpoint, in metaphase - Usual diagram — Cell cycle: A circle | Mitosis: A row of cells, one per stage Draw the cell cycle as a circle and mitosis as a sequence. Cytokinesis is usually counted in the M phase but is a separate process from mitosis. #### Where are cell cycle diagrams used? Cell cycle diagrams are used mostly in biology teaching — from school units on cell division to university cell and cancer biology — and as figures in papers on proliferation, DNA damage and cancer drugs. The detail rises with the level: four phases for a first lesson, checkpoints and cyclin–CDK pairs for an exam or a paper. - School biology: Cell division units in middle and high school, AP Biology and A-level, usually a labeled circle plus the same diagram blank for students to label. - University cell biology: Lectures and exam questions on checkpoints, cyclins and CDKs, Rb and E2F, p53 and p21, and how the cycle is switched on and off. - Cancer research: Figures showing where a mutation or a drug interferes with a checkpoint or a cyclin–CDK complex, and at which phase the cells stop. - Posters and lab reports: A clean cell cycle as the background panel for flow cytometry results, cell-synchronization experiments or a science-fair board. #### Common questions about the cell cycle **How do I draw a cell cycle diagram?** Draw a circle, divide it clockwise into G1, S, G2 and M with each arc sized to how long the phase takes, bracket G1, S and G2 as interphase, branch G0 off G1 and mark the checkpoints at G1/S, G2/M and in metaphase. With this maker you describe the version you need and the circle is drawn in that order. **What are the phases of the cell cycle?** Interphase — G1, S and G2 — and the M phase, which is mitosis (prophase, prometaphase, metaphase, anaphase, telophase) followed by cytokinesis. Cells that stop dividing leave G1 for G0. **What happens during interphase?** The cell grows and copies its DNA: in G1 it grows and makes proteins and organelles, in S it replicates every chromosome into two sister chromatids and duplicates the centrosome, and in G2 it makes the proteins needed for mitosis. Interphase fills about 23.5 hours of a 24-hour human cycle; the G1/S checkpoint guards the step from G1 into S, and the G2/M checkpoint the step from G2 into mitosis. **Can I get a labeled cell cycle diagram and a blank one to label?** Yes — both are on this page free: the labeled cell cycle is the answer key and the blank one has an empty answer line for every phase, checkpoint and regulator. You can also generate a new pair at any level of detail. **What are the three cell cycle checkpoints?** The G1/S checkpoint (restriction point), the G2/M checkpoint and the spindle (M) checkpoint in metaphase. They check, in turn, whether conditions and the DNA are fit for replication, whether all DNA has been copied without damage, and whether every chromosome is attached to the spindle. **Which cyclin–CDK complexes control the cell cycle?** Cyclin D–CDK4/6 in G1, cyclin E–CDK2 at the G1/S transition, cyclin A–CDK2 during S phase and cyclin B–CDK1 at the G2/M transition. The CDK levels stay steady; the cyclin levels rise and fall, so each complex is active only in its window. **What is the G0 phase?** G0 is a resting state outside the cycle, where a cell does its job without preparing to divide. Some cells return to G1 when signaled; mature cardiac muscle and nerve cells stay in G0 permanently. **How long does each phase of the cell cycle last?** In rapidly dividing human cells with a 24-hour cycle, about 9 hours in G1, 10 in S, 4.5 in G2 and 0.5 in M. The cycle ranges from about eight minutes in early fruit-fly embryos to a lifetime spent in G0 for some human cells. **What do p53 and Rb do in the cell cycle?** Both are brakes that act mainly at the G1 checkpoint. p53 halts the cycle when it detects damaged DNA and switches on p21, which blocks cyclin–CDK complexes; Rb holds the transcription factor E2F until CDKs phosphorylate it, releasing E2F to start S phase. **What happens when cell cycle checkpoints fail?** Cells divide with damaged or wrongly separated chromosomes, and unchecked division is a route to cancer. Rb, p53 and p21 were all first found faulty in cancer cells, and TP53, the gene for p53, is mutated in more than half of human tumors. **Is the cell cycle the same as mitosis?** No. Mitosis is the division of the nucleus inside the M phase; the cell cycle also includes interphase, when the cell grows and copies its DNA. The comparison table above sets them side by side. #### Sources - The Cell Cycle — Biology 2e, section 10.2 — OpenStax: https://openstax.org/books/biology-2e/pages/10-2-the-cell-cycle - Control of the Cell Cycle — Biology 2e, section 10.3 — OpenStax: https://openstax.org/books/biology-2e/pages/10-3-control-of-the-cell-cycle - Cell Cycle, Mitotic (R-HSA-69278) — Reactome: https://reactome.org/content/detail/R-HSA-69278 - G1/S Transition (R-HSA-69206) — Reactome: https://reactome.org/content/detail/R-HSA-69206 --- ### Food Web Maker — Labeled & Blank Food Web Diagrams, Free URL: https://scientificfigure.com/tools/food-web-maker Description: Create a food web in seconds: producers, consumers and decomposers linked by arrows that follow energy flow. Free labeled and blank food web templates. #### What is a food web? A food web diagram shows the feeding relationships in one ecosystem: producers such as plants and algae at the base, the consumers that eat them stacked above by trophic level, and decomposers that break down the remains, all joined by arrows that point from the organism eaten to the organism that eats it — the direction energy flows. Where a food chain follows one path, a food web shows all of them at once. - Arrows follow the energy, not the hunt. Each arrow points from the organism that is eaten to the organism that eats it: grass → rabbit → fox. An arrow from the fox to the rabbit reverses the flow of energy, and it is the most common mistake on a food web worksheet. - Every web rests on producers. Plants, algae and phytoplankton make their own food, mostly by photosynthesis, and form the first trophic level; herbivores are the primary consumers, and the carnivores that eat them are secondary and tertiary consumers. - Energy shrinks at every step. In Howard T. Odum’s classic study of Silver Springs, Florida, producers made 20,819 kcal/m²/yr, primary consumers 3,368, secondary consumers 383 and tertiary consumers just 21 — which is why food chains rarely run past four or five levels. - One animal can feed on several levels. Omnivores such as bears eat both berries and salmon, and a snake that eats mice and frogs is a secondary and a tertiary consumer at once. - Decomposers recycle matter, not energy. Fungi and bacteria break down dead organisms and wastes from every level and return nutrients to the soil or water for producers to reuse; the energy itself leaves the web as heat. #### Trophic levels in a food web The roles a labeled food web is normally expected to show, what each one eats, examples from a temperate forest, and where each goes on the diagram. This is the default layout unless you ask for something else. - Producers (1st trophic level) — What it eats: Nothing — makes its own food from sunlight, carbon dioxide and water by photosynthesis | Forest examples: Oak tree, grass, berry bush | Where to draw it: Along the bottom row - Primary consumers (2nd level) — What it eats: Producers — they are herbivores | Forest examples: Caterpillar, grasshopper, rabbit, mouse | Where to draw it: In the row above the producers - Secondary consumers (3rd level) — What it eats: Primary consumers | Forest examples: Songbird, frog, fox | Where to draw it: In the row above the herbivores - Tertiary consumers (4th level) — What it eats: Secondary consumers | Forest examples: Hawk eating snakes and songbirds | Where to draw it: Near the top - Apex predators — What it eats: Other consumers; nothing preys on them as adults | Forest examples: Hawk, great horned owl, wolf | Where to draw it: At the very top - Omnivores — What it eats: Both producers and consumers | Forest examples: Black bear, raccoon | Where to draw it: Between rows, with arrows coming in from plants and from animals - Decomposers — What it eats: Dead organisms and wastes from every level | Forest examples: Fungi, bacteria | Where to draw it: To one side, with arrows coming in from every level - Detritivores — What it eats: Dead plant and animal matter, eaten whole | Forest examples: Earthworms, millipedes, woodlice | Where to draw it: Beside the decomposers Arrows always point toward the eater. Most worksheets also ask for the trophic level names down the side and for decomposers linked to every level. Name the organisms you need and only those are drawn. #### Food chain vs food web: what is the difference? A food chain is a single path of energy from a producer to a top consumer, such as grass → rabbit → fox; a food web joins every food chain in an ecosystem into one network, so each organism can have several foods and several predators. The web is the more realistic model; the chain is easier to read and to test on. - Shape — Food chain: One straight line | Food web: A network of crossing links - Paths for energy — Food chain: One | Food web: Many, overlapping - Organisms per trophic level — Food chain: Usually one | Food web: Several - Foods per animal — Food chain: One | Food web: Often several; omnivores feed on more than one level - What it shows well — Food chain: The order of trophic levels and the energy lost at each step | Food web: Competition, omnivory and how losing one species affects the others - If one species disappears — Food chain: The chain simply breaks | Food web: Other links can make up for it, or the loss cascades through the web - Typical use — Food chain: First introductions in primary school | Food web: Middle school onward, ecology courses and research Draw a food chain as one row of arrows and a food web as rows by trophic level, with the same arrow rule in both: from the organism eaten to the organism that eats it. #### Where are food web diagrams used? Food web diagrams are used mostly in science teaching — from elementary ecosystem units to university ecology — and as figures in ecology papers, conservation reports and environmental assessments. What changes is the size: five organisms for a first lesson, dozens of species with measured links in research. - School science: Ecosystem units from elementary through high school, including the NGSS models of matter and energy flow (5-LS2-1, MS-LS2-3). Usually a labeled web, plus the same drawing blank for students to complete. - University ecology: Lecture slides and exam questions on trophic levels, energy transfer efficiency, trophic cascades and biomagnification, where a pesticide such as DDT concentrates up the web. - Conservation and fieldwork: Figures for reports on a lake, a reef or a reserve, showing which species depend on one another before an invasive species arrives or a keystone predator is lost. - Posters and science fairs: A clear web of a local habitat — a pond, a school garden, a kelp forest — for a poster, a presentation or a science-fair board. #### Common questions about food webs **How do I create a food web?** List the organisms in one ecosystem, sort them by what they eat — producers, primary, secondary and tertiary consumers, decomposers — and draw an arrow from each food to every animal that eats it. With this maker you describe the habitat or paste your list, and the web is drawn in rows by trophic level with every arrow pointing the right way. **Which way do the arrows go in a food web?** From the organism that is eaten to the organism that eats it — the direction energy flows. Grass → rabbit means the rabbit eats the grass. Arrows drawn from predator to prey are the error teachers see most often. **Can I get a blank food web for students to fill in?** Yes — view the blank version on this page free, or ask for one and every organism and trophic level name is replaced by an empty answer line. The labeled version is the matching answer key, so the two print as a pair. **Is there a free food web template?** Yes. The labeled and blank temperate forest food webs on this page are free to view, and you can generate a new template for any ecosystem. Ask for a pond, desert, ocean or grassland web and name the organisms your class studies. **What is the difference between a food chain and a food web?** A food chain follows one path of energy, such as grass → rabbit → fox; a food web joins all the food chains of an ecosystem, so one animal can eat several foods and be eaten by several predators. The comparison table above sets them side by side. **What are the trophic levels in a food web?** Producers form the first trophic level, herbivores (primary consumers) the second, carnivores that eat herbivores (secondary consumers) the third, and carnivores that eat other carnivores (tertiary consumers) the fourth, with apex predators at the top. Decomposers feed on dead matter from every level. **Where do decomposers go on a food web?** Usually to one side or along the bottom, with arrows running into them from every trophic level, since the remains of every level end up there. Some worksheets leave them out; ask for a web without decomposers and none are drawn. **Why do food webs rarely have more than four or five levels?** Because most of the energy at each level is used for living and lost as heat, so only a small fraction — often around 10% — passes to the next level. In Odum’s Silver Springs study, the tertiary consumers got about 0.1% of the energy the producers made. **What happens to a food web if one species is removed?** The effect spreads along its links. When sea otters decline, the sea urchins they eat multiply and strip the kelp forest bare — a trophic cascade. Ask for two webs side by side to show a food web before and after the loss. **Can I make a food chain instead?** Yes — ask for a food chain and the maker draws one row of organisms joined by arrows, from a producer to a top consumer, with the trophic level named under each. **What is an example of a food web?** In a temperate forest, grass is eaten by grasshoppers and rabbits, grasshoppers by songbirds, frogs and snakes, rabbits by snakes and foxes, and snakes by hawks and owls, while fungi and bacteria break down whatever dies. That is the labeled food web on this page. The list above gives a cast for the ocean, rainforest, desert, tundra and other ecosystems, and any of them can be drawn here. #### Sources - Ecology of Ecosystems — Biology 2e, section 46.1 — OpenStax: https://openstax.org/books/biology-2e/pages/46-1-ecology-of-ecosystems - Energy Flow through Ecosystems — Biology 2e, section 46.2 — OpenStax: https://openstax.org/books/biology-2e/pages/46-2-energy-flow-through-ecosystems - Food Web — National Geographic Education: https://education.nationalgeographic.org/resource/food-web/ --- ### Pedigree Chart Maker — Free Pedigree Diagram Generator URL: https://scientificfigure.com/tools/pedigree-chart-maker Description: Make a genetic pedigree chart in standard symbols: squares, circles, shaded affected, carriers, generations I–III, for autosomal or X-linked traits. #### What is a pedigree chart? A pedigree chart, or pedigree diagram, maps a family across generations to show who has a genetic trait or condition: males as squares, females as circles, affected individuals shaded, partners joined by a horizontal line and their children hanging below from a sibship line, with the generations numbered I, II, III. The pattern of shaded symbols tells you how the trait is inherited. - The symbols are standardized. The National Society of Genetic Counselors published standard human pedigree nomenclature in 1995 and updated it in 2008 (Bennett et al., J Genet Couns 17:424) and again in 2022; clinics, textbooks and exams follow it. - Shading means affected; carriers get their own mark. A filled symbol marks someone who has the condition. The 2008 standard puts a dot in the centre of a carrier’s symbol, the convention most textbooks and this page still use; the 2022 update drops the dot for a divided symbol with one part patterned and explained in the legend, and many textbooks simply shade half the symbol. - Lines carry the relationships. A horizontal relationship line joins partners (a double line if they are blood relatives), a vertical line of descent drops to the sibship line, and siblings hang from it in birth order, oldest on the left. - Every person has an address. Generations are numbered with Roman numerals from the top and individuals with Arabic numerals from left to right, so II-3 is the third person in generation II. An arrow marks the proband, the person through whom the family came to attention. - Three generations is the usual minimum. Genetic counselors normally record at least three generations — enough to see whether a condition skips a generation, affects mainly males or passes from father to son. #### Standard pedigree symbols and what they mean The symbols a pedigree chart is normally expected to use, following the National Society of Genetic Counselors nomenclature. This is the default set unless you ask for another convention. - Square — Meaning: Male | How it is drawn: An open square - Circle — Meaning: Female | How it is drawn: An open circle - Diamond — Meaning: Sex unknown or not specified | How it is drawn: An open diamond - Filled symbol — Meaning: Affected — has the condition or trait | How it is drawn: The square, circle or diamond shaded solid - Dot in the symbol — Meaning: Carrier (2008 convention) | How it is drawn: A small dot in the centre; the 2022 update divides the symbol and patterns one part instead, and many textbooks shade half - Diagonal line — Meaning: Deceased | How it is drawn: A line drawn across the symbol - Horizontal line between two symbols — Meaning: Relationship between partners | How it is drawn: A single line; a double line if the partners are related by blood - Line of descent and sibship line — Meaning: Children of a couple | How it is drawn: A vertical line from the relationship line to a horizontal sibship line, each child hanging from it in birth order - Arrow — Meaning: Proband | How it is drawn: An arrow at the lower left of the symbol, with a P - Roman and Arabic numerals — Meaning: Generation and individual | How it is drawn: I, II, III down the left; 1, 2, 3 from left to right within each generation Put the legend on the chart. A pedigree that shows more than one condition, or half-shaded carriers, must say what each shading means. Name the symbols you need and only those are drawn. #### Autosomal recessive vs autosomal dominant: how to tell them apart on a pedigree In an autosomal recessive pedigree, affected children are usually born to two unaffected carrier parents and the trait can skip generations; in an autosomal dominant pedigree, every affected person has an affected parent and the trait appears in every generation. Both affect males and females about equally, which sets them apart from X-linked inheritance. - Parents of an affected child — Autosomal recessive: Usually both unaffected carriers | Autosomal dominant: At least one affected parent, unless it is a new mutation - Across generations — Autosomal recessive: Can skip one or more | Autosomal dominant: Appears in every generation - Chance for each child — Autosomal recessive: 25% when both parents are carriers | Autosomal dominant: 50% when one parent is affected - Males and females — Autosomal recessive: Affected about equally | Autosomal dominant: Affected about equally - Father-to-son transmission — Autosomal recessive: Possible | Autosomal dominant: Possible, which rules out X-linked inheritance - Parents related by blood — Autosomal recessive: Often seen; it raises the chance | Autosomal dominant: Not a typical clue - Examples — Autosomal recessive: Cystic fibrosis, sickle cell disease, phenylketonuria | Autosomal dominant: Huntington disease, Marfan syndrome, familial hypercholesterolemia Check X-linked inheritance before settling on either. If mostly males are affected and no affected father has an affected son, test the X-linked recessive pattern; an affected father whose daughters are all affected and sons all unaffected points to X-linked dominant. #### Where are pedigree charts used? Pedigree charts are used in genetics teaching, genetic counselling and medical research — anywhere a trait has to be traced through a family. The chart is the same; what changes is the detail, from a five-person worksheet to a clinical record with ages and test results. - School and university genetics: Worksheets and exam questions that ask students to identify the mode of inheritance, assign genotypes and work out the chance that the next child is affected, from AP Biology, A-level and IB to first-year genetics. - Genetic counselling: Family histories drawn at the first appointment, usually across at least three generations, to assess risk and decide who should be offered testing. - Case reports and research papers: The family figure in a case report or a gene-discovery paper, showing which relatives were affected and which were tested. - Patient and family education: A clear chart that explains to a family why a condition appeared, who may be a carrier and what the odds are for a future pregnancy. #### Common questions about pedigree charts **How do I make a pedigree chart?** Start with the oldest generation at the top: draw each couple as a square and a circle joined by a horizontal line, drop a vertical line to a sibship line, and hang their children from it in birth order; shade everyone who is affected, then number the generations I, II, III and the individuals 1, 2, 3. With this maker you describe the family in plain words and the chart is drawn in that notation. **What do the symbols on a pedigree chart mean?** Squares are males, circles are females and diamonds are individuals of unknown sex; a filled symbol means affected, a dot in the centre (or a half-patterned symbol) means carrier, and a diagonal line means deceased. An arrow marks the proband. The table above lists the full standard set. **What is a famous pedigree chart example?** The hemophilia pedigree of Queen Victoria’s descendants, the classic X-linked recessive example. Victoria was a carrier; her son Leopold had hemophilia, and her daughters Alice and Beatrice were carriers who passed it into the royal families of Russia, Prussia and Spain — Tsarevich Alexei of Russia, a great-grandson, was affected. It shows every X-linked sign at once: affected males, carrier mothers and no father-to-son transmission. **How do you tell if a trait is dominant or recessive from a pedigree?** If two unaffected parents have an affected child, the trait is recessive; if it shows up in every generation and each affected person has an affected parent, it is most likely dominant. Then check the sexes: mostly affected males and no father-to-son transmission point to X-linked recessive. **How do I work out genotypes on a pedigree?** Start with the people whose genotype is certain: for a recessive trait every affected person is aa, so their unaffected parents and children must be Aa. Fill in the rest from there, writing A_ where the second allele cannot be known. An unaffected child of two carriers has a 2/3 chance of being a carrier. **How are generations and individuals numbered?** Generations take Roman numerals from the top — I, II, III — and individuals take Arabic numerals from left to right within each generation, so every person has a unique label such as III-2. **What is a proband?** The proband is the affected person through whom the family first came to medical attention, marked by an arrow with a P at the lower left of the symbol. The consultand, the person seeking advice, gets an arrow without the P. **Should carriers be half-shaded or shown with a dot?** Either works as long as the legend says which: the 2008 NSGC standard and most textbooks put a dot in the centre of the symbol, while the 2022 NSGC update drops the dot and divides the symbol, filling one part with a pattern named in the legend — which can also show a person who carries more than one condition. Ask for either, and the legend states the one used. **What changed in the 2022 update of the pedigree standard?** The 2022 NSGC update makes the symbol shape reflect gender identity, with sex assigned at birth (AMAB, AFAB or UAAB) written below the symbol, and replaces the carrier dot with a divided symbol whose patterned part is explained in the legend. Ask for this notation if your course or clinic uses it. **Can I use it for dog, horse or family-history pedigrees?** No — this maker draws human genetic pedigrees in medical notation, for tracing a trait or a condition through a family. Animal-breeding pedigrees and genealogy family trees follow different layouts and conventions, and it is not built for them. **Can I use the pedigree charts for school, clinic or publication?** Yes — charts you generate are yours to use in worksheets, slides, case reports and papers. Do not enter the names or other identifying details of real patients; describe people by generation and number instead. Export high-resolution raster up to 4K depending on the model. #### Sources - Standardized human pedigree nomenclature: update and assessment of the recommendations of the National Society of Genetic Counselors — J Genet Couns 17:424–433 (2008) — Bennett RL et al., Journal of Genetic Counseling: https://doi.org/10.1007/s10897-008-9169-9 - Standardized pedigree nomenclature update centered on sex and gender inclusivity — J Genet Couns 31:1238–1248 (2022) — Bennett RL et al., Journal of Genetic Counseling: https://doi.org/10.1002/jgc4.1621 - Pedigree — Talking Glossary of Genomic and Genetic Terms — National Human Genome Research Institute: https://www.genome.gov/genetics-glossary/Pedigree --- ### Insulin Signaling Pathway Diagram — Labeled, by Tissue, Free URL: https://scientificfigure.com/tools/insulin-signaling-pathway Description: Free insulin signaling pathway diagram maker: insulin receptor, IRS-1, PI3K, Akt and GLUT4 in order, plus insulin resistance and muscle, liver and fat versions. #### What is the insulin signaling pathway? The insulin signaling pathway is the chain of events by which insulin, bound to the insulin receptor tyrosine kinase, phosphorylates IRS proteins and activates PI3K and Akt, which move GLUT4 to the cell surface, switch on glycogen and protein synthesis, and turn down glucose production in the liver. A second branch through Shc, Grb2, Ras and MAPK carries insulin's growth signal. - The insulin receptor is already a tetramer before insulin arrives. Two extracellular α subunits bind insulin and two membrane-spanning β subunits carry the tyrosine kinase; binding brings the two kinase domains together so they phosphorylate each other. - Most docking sites are on IRS, not on the receptor. The autophosphorylated receptor phosphorylates insulin receptor substrate proteins on many tyrosines, and the p85 regulatory subunit of PI3K binds them through its SH2 domains. - Akt works mostly by switching other proteins off. It inactivates AS160 (TBC1D4) to release GLUT4 vesicles, inactivates GSK3 so glycogen synthase stays active, and phosphorylates FOXO1 so it leaves the nucleus and the gluconeogenic genes quiet down. - GLUT4 translocation is the muscle and fat response. Insulin moves GLUT4 to the plasma membrane in skeletal muscle, adipose tissue and heart muscle; in muscle, contraction can do the same through AMPK without insulin. - Insulin resistance starts at IRS. In obesity and type 2 diabetes, serine/threonine kinases such as JNK, IKKβ and PKCθ phosphorylate IRS-1 on serines, which blunts its signal to PI3K and Akt and so reduces GLUT4 translocation and glycogen synthesis. #### Steps of the insulin signaling pathway and what each one does The nodes a labeled insulin signaling pathway diagram is normally expected to show, in order, what each one does and what it acts on next. This is the default label set unless you ask for a shorter one. - Insulin — What it does: Peptide hormone from pancreatic β cells, released when blood glucose rises | Acts on next: The α subunits of the insulin receptor - Insulin receptor (α2β2) — What it does: Receptor tyrosine kinase; insulin binding makes its β subunits phosphorylate each other | Acts on next: IRS-1/2 and Shc, on tyrosines - IRS-1 and IRS-2 — What it does: Docking proteins that carry many phosphotyrosine sites | Acts on next: PI3K (through its p85 subunit) and Grb2 - PI3K (p85/p110) — What it does: Lipid kinase that turns PIP2 into PIP3 in the inner leaflet of the membrane | Acts on next: PIP3 recruits PDK1 and Akt - PDK1 — What it does: Phosphorylates Akt at Thr308; mTORC2 adds Ser473 | Acts on next: Akt - Akt (PKB) — What it does: Serine/threonine kinase at the center of the metabolic branch | Acts on next: AS160, GSK3, FOXO1 and, through TSC2 and Rheb, mTORC1 - AS160 (TBC1D4) — What it does: Rab-GAP that holds GLUT4 vesicles inside the cell; switched off by Akt | Acts on next: GLUT4 vesicles move to the plasma membrane and fuse with it - GLUT4 — What it does: Glucose transporter of skeletal muscle, heart muscle and fat cells | Acts on next: Glucose enters the cell - GSK3 — What it does: Kinase that keeps glycogen synthase inactive; switched off by Akt | Acts on next: Glycogen synthase stays active → glycogen - FOXO1 — What it does: Transcription factor for gluconeogenic genes; Akt sends it out of the nucleus | Acts on next: Less PEPCK and glucose-6-phosphatase → less glucose from the liver - mTORC1 — What it does: Growth kinase complex activated downstream of Akt | Acts on next: S6K1 and 4E-BP1 → protein synthesis - Shc → Grb2 → SOS → Ras → Raf → MEK → ERK — What it does: The mitogenic branch, independent of IRS-1 | Acts on next: Gene transcription and cell growth Textbook figures put the muscle and liver branches in one cell, but they happen in different tissues. GLUT4 translocation is the muscle and fat response; FOXO1 and the brake on gluconeogenesis are the liver response. Some introductory texts even say liver cells lack insulin receptors — the liver in fact has one of the highest receptor densities; what it lacks is insulin-dependent glucose uptake. Name the tissue you want and only that branch is drawn. #### Insulin vs glucagon signaling: what is the difference? Insulin signals through a receptor tyrosine kinase and the PI3K–Akt cascade to store fuel and lower blood glucose; glucagon signals through a G protein-coupled receptor, cAMP and protein kinase A to release glucose from the liver and raise it. The two are drawn side by side because they push the same liver enzymes in opposite directions. - Made by — Insulin: β cells of the pancreatic islets | Glucagon: α cells of the pancreatic islets - Released when — Insulin: Blood glucose rises after a meal | Glucagon: Blood glucose falls, and after a protein meal - Receptor — Insulin: Insulin receptor, a receptor tyrosine kinase (α2β2) | Glucagon: Glucagon receptor, a seven-transmembrane GPCR coupled to Gs - First relay — Insulin: IRS phosphorylation → PI3K → PIP3 | Glucagon: Adenylyl cyclase → cAMP - Main kinase — Insulin: Akt (PKB) | Glucagon: Protein kinase A - Main targets — Insulin: Skeletal muscle, fat and liver | Glucagon: Liver - Glycogen — Insulin: Synthesis up: GSK3 off, glycogen synthase on | Glucagon: Breakdown up: glycogenolysis - Gluconeogenesis — Insulin: Suppressed: FOXO1 leaves the nucleus | Glucagon: Stimulated: PKA phosphorylates CREB - Blood glucose — Insulin: Lowered | Glucagon: Raised Draw them as two separate cascades, not as one pathway: insulin's arrows end in glycogen synthesis and less gluconeogenesis, glucagon's in glycogen breakdown and more. A glucagon receptor drawn as a tyrosine kinase, or insulin acting through cAMP, is the error to check for first. #### Where are insulin signaling pathway diagrams used? Insulin signaling diagrams are used mostly in physiology, biochemistry and medical teaching, and as model figures in diabetes and metabolism research. What changes between them is the depth: eight labels for a first course, the full cascade with its negative regulators for a medical or graduate one. - Physiology and biochemistry courses: Lectures and exam revision on blood glucose control, where the pathway links the islet hormones to GLUT4, glycogen and gluconeogenesis. - Medical teaching: Pathophysiology of type 2 diabetes and insulin resistance, showing which step fails and why muscle takes up less glucose while the liver keeps making it. - School biology: AP Biology, A-level and IB units on cell signaling that use the insulin receptor as the example of a receptor tyrosine kinase, usually as a simple overview. - Research figures: Graphical abstracts and model figures in diabetes, obesity and metabolism papers, with the protein under study highlighted in the cascade. #### Common questions about the insulin signaling pathway **What are the steps of the insulin signaling pathway?** Insulin binds its receptor; the receptor phosphorylates itself and IRS-1; IRS-1 recruits PI3K; PI3K makes PIP3; PIP3 brings PDK1 and Akt to the membrane; and active Akt drives GLUT4 translocation, glycogen synthesis and protein synthesis while switching off gluconeogenesis. In parallel, Shc and Grb2 recruit SOS to activate Ras and the MAPK cascade. **What should a labeled insulin signaling pathway diagram include?** The standard set is insulin, the insulin receptor with its α and β subunits, IRS-1, PI3K, PIP2 and PIP3, PDK1, Akt, AS160, GLUT4, GSK3, glycogen synthase, FOXO1 and mTORC1, plus the Shc–Grb2–SOS–Ras–MAPK branch. Medical and graduate figures add the negative regulators PTP1B and PTEN. Ask for fewer labels and only those are drawn. **How does insulin make GLUT4 move to the cell membrane?** Akt phosphorylates AS160 (TBC1D4), a Rab-GAP that normally keeps GLUT4 vesicles inside the cell; switched off, it lets Rab proteins stay GTP-bound, and the vesicles travel to the plasma membrane and fuse with it. Muscle contraction can trigger the same move through AMPK, without insulin. **How does insulin increase glycogen synthesis?** Akt phosphorylates and inactivates GSK3, the kinase that keeps glycogen synthase switched off, so glycogen synthase stays active. Protein phosphatase 1 adds to this by dephosphorylating glycogen synthase and inactivating glycogen phosphorylase, so glycogen breakdown slows at the same time. **How does insulin stop the liver from making glucose?** Akt phosphorylates the transcription factor FOXO1, which leaves the nucleus, so the genes for gluconeogenic enzymes are switched down. Insulin lowers the expression of PEPCK, fructose-1,6-bisphosphatase and glucose-6-phosphatase and raises glucokinase and pyruvate kinase, shifting the liver from making glucose to storing it. **What goes wrong in the insulin signaling pathway in insulin resistance?** The signal is cut near the top: serine/threonine kinases such as JNK, IKKβ and PKC phosphorylate IRS-1 on serines, mTOR signaling speeds IRS-1 degradation, and phosphatases such as PTP1B and PTEN are more active, so PI3K and Akt are activated less. The result is less GLUT4 translocation and glycogen synthesis in muscle and more gluconeogenesis in the liver. In muscle, fat-derived diacylglycerol activates PKCθ; in the liver, PKCε. **What are the negative regulators of insulin signaling?** PTP1B dephosphorylates the insulin receptor, PTEN turns PIP3 back into PIP2, SOCS proteins bind the signaling complex and block IRS-1, and serine phosphorylation of IRS-1 shuts the signal down at its source. One of those serine kinases is S6K1, downstream of mTORC1, which makes a built-in negative feedback loop. **What is the difference between the insulin signaling pathway and the PI3K/AKT pathway?** The PI3K/AKT pathway is the general module that many growth factors use; the insulin signaling pathway is one way into it, through the insulin receptor and IRS proteins, read out mainly as metabolism — GLUT4, glycogen and gluconeogenesis. For the generic module as cell biology and cancer draw it, with TSC2, mTORC1, BAD and MDM2, use the PI3K/AKT signaling pathway diagram maker. #### Sources - Insulin signaling pathway (hsa04910) — KEGG PATHWAY: https://www.kegg.jp/entry/hsa04910 - Translocation of SLC2A4 (GLUT4) to the plasma membrane — Reactome: https://reactome.org/content/detail/R-HSA-1445148 - Insulin resistance (hsa04931) — KEGG PATHWAY: https://www.kegg.jp/entry/hsa04931 - Biochemistry, Insulin Metabolic Effects — StatPearls — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK525983/ --- ### PI3K/AKT Signaling Pathway Diagram — Labeled with mTOR, Free URL: https://scientificfigure.com/tools/pi3k-akt-signaling-pathway Description: Free PI3K/AKT pathway diagram maker: PI3K, PIP3, PTEN, PDK1, mTORC2 and AKT with its targets mTORC1, FOXO, BAD and MDM2. PI3K/AKT/mTOR in cancer too. #### What is the PI3K/AKT signaling pathway? The PI3K/AKT signaling pathway is the module in which an activated receptor recruits class I PI3K, PI3K converts PIP2 into PIP3 at the membrane, and PIP3 brings AKT to PDK1 and mTORC2, which phosphorylate it so it can switch on mTORC1 and switch off TSC2, GSK3β, FOXO and BAD. Its outputs are cell growth, survival and metabolism; the phosphatase PTEN turns it off. - Class I PI3K is a two-part enzyme. A p85 regulatory subunit keeps the p110 catalytic subunit inactive until its SH2 domains bind phosphotyrosines on an activated receptor or adaptor; receptor tyrosine kinases activate class IA isoforms and G protein-coupled receptors class IB. - PIP3 is the signal, and PTEN erases it. PI3K adds a phosphate at the 3 position of the inositol ring of PIP2; PTEN takes it off again, so losing PTEN leaves PIP3 — and AKT — switched on. - AKT needs two phosphates to be fully active. PDK1 phosphorylates Thr308 and mTORC2 phosphorylates Ser473 (numbering of AKT1). Reactome puts Ser473 first, as the step that lets PDK1 reach Thr308; older textbooks, such as the 2002 edition of Alberts' Molecular Biology of the Cell, show PDK1 alone. - AKT mostly works by switching its targets off. Phosphorylation inactivates TSC2, so Rheb can activate mTORC1, and inactivates GSK3β, the FOXO transcription factors (exported from the nucleus) and the pro-apoptotic protein BAD (held by 14-3-3); MDM2 is the exception, sent into the nucleus to degrade p53. - It is often switched on permanently in cancer. Gain-of-function mutations in PIK3CA (p110α) and PIK3R1 (p85α), the rare AKT1 E17K mutation and loss-of-function mutations in PTEN all keep the pathway active without a growth factor. #### Components of the PI3K/AKT pathway and what each one does The nodes a labeled PI3K/AKT pathway diagram is normally expected to show, in order, what each one does and what it acts on next. This is the default label set unless you ask for a shorter one. - Receptor tyrosine kinase or GPCR — What it does: Binds a growth factor or other ligand and becomes active | Acts on next: Recruits PI3K: an RTK through phosphotyrosines, a GPCR through Gβγ - Class I PI3K (p85/p110) — What it does: Lipid kinase; p85 binds the receptor, p110 phosphorylates PIP2 | Acts on next: Makes PIP3 - PIP3 — What it does: Lipid messenger in the inner leaflet of the plasma membrane | Acts on next: Recruits PDK1 and AKT through their PH domains - PTEN — What it does: Lipid phosphatase and tumor suppressor | Acts on next: Turns PIP3 back into PIP2, switching AKT off - PDK1 and mTORC2 — What it does: Phosphorylate AKT at Thr308 (PDK1) and Ser473 (mTORC2) | Acts on next: Fully active AKT - AKT (AKT1, AKT2, AKT3) — What it does: Serine/threonine kinase that leaves the membrane to phosphorylate its targets | Acts on next: TSC2, GSK3β, FOXO, BAD, MDM2 - TSC1/TSC2 — What it does: GAP complex that keeps Rheb in its inactive GDP-bound form; inhibited by AKT | Acts on next: Rheb - Rheb → mTORC1 — What it does: GTP-bound Rheb activates mTORC1 | Acts on next: S6K1 and 4E-BP1 → protein synthesis and cell growth - GSK3β — What it does: Kinase inhibited by AKT | Acts on next: Glycogen synthase and other metabolic targets - FOXO — What it does: Transcription factors exported from the nucleus once AKT phosphorylates them | Acts on next: Genes for apoptosis, cell-cycle arrest and glucose metabolism go quiet - BAD — What it does: Pro-apoptotic protein; held by 14-3-3 once AKT phosphorylates it | Acts on next: Apoptosis blocked, cell survival - MDM2 — What it does: E3 ubiquitin ligase; AKT phosphorylation sends it into the nucleus | Acts on next: p53 degraded Draw AKT's targets as inhibition bars, not arrows — except MDM2. TSC2, GSK3β, FOXO and BAD are all inactivated when AKT phosphorylates them, so mTORC1 is switched on by a double negative (AKT ⊣ TSC2 ⊣ Rheb). A diagram with plain arrows from AKT to every target gets four of the five backwards. #### PI3K/AKT vs Ras/MAPK: what is the difference? Both start at the same activated receptor tyrosine kinases, but PI3K/AKT relays the signal through a membrane lipid, PIP3, and one kinase, AKT, to control growth, survival and metabolism, while Ras/MAPK relays it through a GTPase switch and a three-kinase cascade, Raf → MEK → ERK, mainly to control proliferation and differentiation through gene transcription. The two cross-talk: GTP-bound Ras can bind and activate p110. - Adaptor at the receptor — PI3K/AKT: p85 subunit of PI3K, through its SH2 domains | Ras/MAPK: Grb2, bound to the GEF SOS; Shc on some receptors - Relay — PI3K/AKT: Lipid messenger PIP3 in the inner membrane leaflet | Ras/MAPK: Small GTPase Ras, active when GTP-bound - Kinase steps — PI3K/AKT: PDK1 and mTORC2 → AKT | Ras/MAPK: Raf → MEK1/2 → ERK1/2 - Main outputs — PI3K/AKT: Cell growth (mTORC1), survival (BAD, FOXO), metabolism | Ras/MAPK: Proliferation and differentiation, immediate early gene transcription - Switched off by — PI3K/AKT: PTEN removing the 3-phosphate from PIP3 | Ras/MAPK: GAPs speeding GTP hydrolysis by Ras - Typical cancer changes — PI3K/AKT: PIK3CA and PIK3R1 gain of function, PTEN loss, AKT1 E17K | Ras/MAPK: Hyperactive RAS mutants, BRAF V600E - Approved inhibitors — PI3K/AKT: Alpelisib, inavolisib, idelalisib (PI3K); capivasertib (AKT); everolimus, temsirolimus (mTOR) | Ras/MAPK: Vemurafenib (BRAF V600E); trametinib (MEK1/2) Draw them as two branches from one receptor, not one line, with Ras able to feed into PI3K. The insulin signaling pathway is the classic teaching example of the split: its IRS–PI3K–AKT branch carries the metabolic effects and its Shc–Grb2–Ras branch the growth effects. #### Where are PI3K/AKT pathway diagrams used? PI3K/AKT diagrams are used in cell biology and cancer teaching, in pharmacology lectures on targeted therapy, and as model figures in cancer and metabolism papers. What changes between them is the depth: an eight-label overview for a first course, all five AKT targets and the drug classes for an advanced one. - Cell biology courses: Signal transduction lectures that use the pathway as the standard example of a lipid second messenger and of a kinase that acts by inhibiting its targets. - Cancer biology: Teaching on oncogenes and tumor suppressors — PIK3CA as the oncogene, PTEN as the tumor suppressor — and on why tumors with these changes are candidates for targeted drugs. - Pharmacology: Slides mapping each approved inhibitor to its node: PI3K inhibitors such as alpelisib, the AKT inhibitor capivasertib and the rapalogs everolimus and temsirolimus on mTORC1. - Research figures: Graphical abstracts and model figures in cancer, metabolism and aging papers, with the node under study highlighted in the cascade. #### Common questions about the PI3K/AKT pathway **What are the steps of the PI3K/AKT pathway?** A growth factor activates its receptor; PI3K docks on it and turns PIP2 into PIP3; PIP3 recruits AKT and PDK1 to the membrane; mTORC2 phosphorylates AKT at Ser473 and PDK1 phosphorylates it at Thr308; and active AKT phosphorylates TSC2, GSK3β, FOXO, BAD and MDM2. PTEN reverses the second step by turning PIP3 back into PIP2. **What does PTEN do in the PI3K/AKT pathway?** PTEN is a lipid phosphatase that removes the 3-phosphate from PIP3, turning it back into PIP2 and so switching AKT off. It is the direct opposite of PI3K, which is why PTEN is drawn beside PI3K at the membrane with an arrow from PIP3 back to PIP2. **Why do PTEN loss and PIK3CA mutations activate the pathway in cancer?** Both leave PIP3 high without a growth factor: activating PIK3CA mutations free p110α from the brake of p85 or lock it in an active shape, and PTEN loss removes the phosphatase that would clear the PIP3. Either way AKT stays active, and cells keep growing and resist apoptosis. The rare AKT1 E17K mutation does the same further down by letting AKT bind PIP2 and be activated without PI3K. **How does AKT activate mTORC1?** Indirectly: AKT phosphorylates TSC2 and breaks up the TSC1/TSC2 complex, a GAP that keeps Rheb inactive, so GTP-bound Rheb accumulates and activates mTORC1. mTORC1 then phosphorylates S6K1, which activates ribosomal protein S6, and 4E-BP1, which releases eIF4E for translation. **What is the difference between mTORC1 and mTORC2?** mTORC1 (with Raptor) sits downstream of AKT and drives protein synthesis and cell growth; mTORC2 (with Rictor) sits upstream, phosphorylating AKT at Ser473. Rapamycin and the rapalogs inhibit only mTORC1, because Rictor masks the rapamycin-binding site in mTORC2. **Which drugs target the PI3K/AKT/mTOR pathway?** Three classes are approved: PI3K inhibitors (alpelisib and inavolisib for PIK3CA-mutant breast cancer, idelalisib for PI3Kδ in chronic lymphocytic leukemia), the AKT inhibitor capivasertib, and the mTOR inhibitors everolimus and temsirolimus. Capivasertib, approved in 2023, is used with fulvestrant for breast cancer with PIK3CA, AKT1 or PTEN alterations. **Why do PI3K and AKT inhibitors raise blood sugar?** Insulin uses the same PI3K–AKT steps to move GLUT4 to the cell surface and to hold back glucose production in the liver, so blocking them blocks part of insulin's action. The alpelisib label warns of severe hyperglycemia and asks for fasting glucose and HbA1c to be checked before treatment starts. **What is the difference between the PI3K/AKT pathway and the insulin signaling pathway?** The insulin signaling pathway is one route into the PI3K/AKT module — through the insulin receptor and IRS proteins — read out as metabolism: GLUT4, glycogen and gluconeogenesis. This page draws the generic module used by many growth factors, with mTORC1, BAD and MDM2; for the physiological version use the insulin signaling pathway diagram maker. #### Sources - PI3K/AKT Signaling in Cancer (R-HSA-2219528) — Reactome: https://reactome.org/content/detail/R-HSA-2219528 - Inhibition of TSC complex formation by AKT (PKB) — Reactome: https://reactome.org/content/detail/R-HSA-165181 - PI3K-Akt signaling pathway (hsa04151) — KEGG PATHWAY: https://www.kegg.jp/entry/hsa04151 - Signaling through Enzyme-Linked Cell-Surface Receptors — Molecular Biology of the Cell, 4th ed. — NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK26822/ --- ### DNA Replication Diagram — Labeled Replication Fork Maker URL: https://scientificfigure.com/tools/dna-replication-diagram Description: Make a labeled DNA replication diagram in seconds: helicase, primase, Okazaki fragments and ligase at the replication fork, plus the bubble and telomerase. #### What is a DNA replication diagram? A DNA replication diagram shows how a cell copies its DNA at a replication fork: helicase separates the two strands, primase lays short RNA primers, DNA polymerase builds each new strand 5′ to 3′ — the leading strand in one piece, the lagging strand as Okazaki fragments — and DNA ligase seals the gaps. Each finished molecule keeps one old strand and one new one. - Replication is semiconservative. Each daughter molecule keeps one parental strand and pairs it with one newly made strand — the result Meselson and Stahl showed by growing E. coli on heavy, then light, nitrogen. - New DNA grows only 5′ to 3′. DNA polymerase adds nucleotides only to a free 3′-OH end, so every new strand starts from a primer and runs antiparallel to its template. - One new strand is continuous, the other is in pieces. The leading strand is built toward the fork from a single primer; the lagging strand is built away from it in short Okazaki fragments, each with its own RNA primer. - Primers are RNA, and they are replaced. Primase makes RNA primers about 5 to 10 nucleotides long; in bacteria DNA polymerase I swaps them for DNA and DNA ligase seals the nicks that remain. - Bacteria start from one origin, eukaryotes from many. E. coli copies its 4.6-million-base-pair chromosome from a single origin in about 42 minutes; the human genome uses up to 100,000 origins. #### Enzymes of DNA replication and what each one does The proteins a labeled DNA replication diagram is normally expected to show, what each one does, and where it sits on the fork. This is the default label set unless you ask for a shorter one. - Helicase — What it does: Unwinds the double helix by breaking the hydrogen bonds between base pairs, using ATP | Where to draw it: At the tip of the fork, where the parent helix splits - Single-strand binding proteins — What it does: Coat the separated strands so they do not pair up again | Where to draw it: Along both exposed single strands - Topoisomerase — What it does: Relieves the over-winding ahead of the fork by nicking and resealing the DNA | Where to draw it: On the unopened double helix ahead of the fork - Primase — What it does: Makes short RNA primers that give DNA polymerase a starting point | Where to draw it: On the templates, one primer per Okazaki fragment on the lagging side - DNA polymerase III — What it does: Main replicating enzyme in bacteria: adds nucleotides 5′ to 3′ | Where to draw it: On both new strands, extending from the primers - Sliding clamp — What it does: Ring that holds DNA polymerase on the DNA as it moves | Where to draw it: Around the DNA at each polymerase - DNA polymerase I — What it does: Removes the RNA primers and fills the gaps with DNA | Where to draw it: On the lagging strand, at the primers of finished fragments - DNA ligase — What it does: Seals the nicks by forming phosphodiester bonds | Where to draw it: Between neighboring Okazaki fragments Courses differ in how many of these they expect. Introductory worksheets often stop at helicase, DNA polymerase and DNA ligase; advanced courses add primase, the sliding clamp and the split between DNA polymerase I and III. Name the labels you need and only those are drawn. #### Leading strand vs lagging strand: what is the difference? The leading strand is built continuously toward the replication fork from one primer; the lagging strand is built away from the fork in short Okazaki fragments, each started by its own RNA primer and later joined by DNA ligase. Both grow 5′ to 3′ — the difference comes from the two template strands running in opposite directions. - Direction of synthesis — Leading strand: Toward the replication fork | Lagging strand: Away from the replication fork - How it is made — Leading strand: Continuously, in one piece | Lagging strand: Discontinuously, as Okazaki fragments - RNA primers — Leading strand: One, at the start | Lagging strand: One for every Okazaki fragment - Template — Leading strand: Complementary to the 3′→5′ parental strand | Lagging strand: Complementary to the 5′→3′ parental strand - Main polymerase in E. coli — Leading strand: DNA polymerase III | Lagging strand: DNA polymerase III - Main polymerase in eukaryotes — Leading strand: DNA polymerase ε | Lagging strand: DNA polymerase δ - After synthesis — Leading strand: Its single primer is replaced with DNA | Lagging strand: Every primer is replaced and DNA ligase joins the fragments Draw the lagging strand as a row of short segments with arrows pointing away from the fork, the newest fragment nearest the fork still carrying its RNA primer. A lagging strand drawn as one continuous arrow, or with arrows pointing into the fork, is the error to check for first. #### Where are DNA replication diagrams used? DNA replication diagrams are used mostly in biology teaching — labeling worksheets, exam revision and lecture slides — and as schematic panels in molecular biology talks and papers. What changes between them is the depth: three labels for a first course, the full fork with the sliding clamp for a university one. - School biology: Labeling worksheets and revision sheets from middle school through GCSE, A-level, AP Biology and IB. Usually the labeled fork, plus the same drawing blank for students to fill in. - University lectures: Molecular biology and genetics slides comparing bacterial and eukaryotic replication: one origin against many, DNA polymerase III against polymerases α, δ and ε, and telomerase at the chromosome ends. - Exam revision: One-page summaries that put every enzyme at its place on the fork — which is how exam questions ask about them: name the enzyme at X, explain why the strand at Y is made in pieces. - Research and teaching figures: Schematic panels for work on replication stress, DNA repair or drugs that target topoisomerases, with the protein under study marked directly on the fork. #### Common questions about DNA replication diagrams **What should a labeled DNA replication diagram include?** The standard set is the parental DNA, the replication fork, helicase, single-strand binding proteins, topoisomerase, primase and its RNA primers, DNA polymerase III, the leading strand, the lagging strand with its Okazaki fragments, DNA polymerase I and DNA ligase, with the 5′ and 3′ ends marked. That is the default — ask for fewer labels and only those are drawn. **What is a replication bubble?** The opened stretch of DNA around an origin of replication, with a replication fork at each end moving away from the other. Because replication runs in both directions from the origin, the bubble grows until it meets its neighbors. A eukaryotic chromosome forms many bubbles at once; the circular E. coli chromosome has a single origin, and its two forks meet on the opposite side of the circle. **Why is the lagging strand made in Okazaki fragments?** Because DNA polymerase can only build a strand 5′ to 3′, and the two template strands run in opposite directions. On one template that direction points into the fork, so synthesis is continuous; on the other it points away, so the polymerase restarts from a new primer each time the fork opens more template. **What is the difference between helicase and topoisomerase?** Helicase separates the two strands at the fork by breaking the hydrogen bonds between base pairs; topoisomerase works ahead of the fork, relieving the over-winding that the unzipping creates. It does that by making temporary nicks in the DNA and resealing them. **What does primase do, and why are RNA primers needed?** Primase makes short RNA primers, about 5 to 10 nucleotides long, that give DNA polymerase the free 3′-OH end it needs. DNA polymerase cannot start a strand on its own. The leading strand needs one primer; the lagging strand needs one for every Okazaki fragment. **What is the difference between DNA polymerase I and DNA polymerase III?** In E. coli, DNA polymerase III is the main replicating enzyme that extends both new strands; DNA polymerase I removes the RNA primers and replaces them with DNA. DNA ligase then seals the nick left between each replaced primer and the fragment beside it. **Why is DNA replication called semiconservative?** Because each new DNA molecule keeps one of the two original strands and pairs it with one newly made strand. Meselson and Stahl grew E. coli on heavy nitrogen, then light: after one generation the DNA formed a single band of intermediate density, and after two a light band appeared beside it — the pattern only semiconservative copying produces. **How is DNA replication in eukaryotes different from prokaryotes?** Eukaryotes replicate from many origins per chromosome — up to 100,000 across the human genome — at about 50 to 100 nucleotides per second, against one origin and about 1,000 nucleotides per second in E. coli. They also use other polymerases (α, δ and ε), the PCNA clamp, RNase H to remove primers, and telomerase to extend the chromosome ends. **Can I make a simple DNA replication drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: the double helix unzipping, each old strand pairing with a new one, and two identical molecules at the end. Five labels or fewer usually covers a middle-school class. **How does the tool keep strand direction and the enzymes correct?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — both strands antiparallel, new DNA growing 5′ to 3′, Okazaki fragments only on the lagging strand — with each label spelled exactly and set on a straight leader line. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a DNA replication diagram from here in a lecture or a paper?** Yes — the replication diagrams you generate are yours to use in genetics worksheets, lecture slides, lab reports and theses. Export goes up to 4K depending on the model. **Can I shorten the enzyme names or translate the labels afterwards?** Yes. The canvas recognizes each label, so you can shorten 'single-strand binding proteins' to 'SSB', translate the set, move a label off the fork or recolor the new strands without regenerating the figure. #### Sources - Basics of DNA Replication — Biology 2e, section 14.3 — OpenStax: https://openstax.org/books/biology-2e/pages/14-3-basics-of-dna-replication - DNA Replication in Prokaryotes — Biology 2e, section 14.4 — OpenStax: https://openstax.org/books/biology-2e/pages/14-4-dna-replication-in-prokaryotes - DNA Replication in Eukaryotes — Biology 2e, section 14.5 — OpenStax: https://openstax.org/books/biology-2e/pages/14-5-dna-replication-in-eukaryotes --- ### Rock Cycle Diagram — Labeled Processes & Simple Drawing URL: https://scientificfigure.com/tools/rock-cycle-diagram Description: Make a labeled rock cycle diagram in seconds: igneous, sedimentary and metamorphic rock, magma and every process arrow, or a simple rock cycle drawing. #### What is a rock cycle diagram? A rock cycle diagram shows how igneous, sedimentary and metamorphic rock turn into one another. Arrows name each process: melting, cooling and crystallization, weathering and erosion, deposition, compaction and cementation, and heat and pressure. - There are three rock types. Igneous rock forms from magma, sedimentary rock from fragments of other rocks or from minerals precipitated out of solution, and metamorphic rock from existing rock altered by heat, pressure or chemical action. - Two energy sources drive the cycle. Earth's internal heat moves material through the mantle and crust; the water cycle, powered by the Sun, moves water, ice and air across the surface. - Where magma cools sets the rock's texture. Magma that cools slowly underground, over centuries to millions of years, forms intrusive igneous rock such as granite; lava that cools at the surface within seconds to years forms extrusive rock such as basalt. - Sediment becomes rock by lithification. Buried sediment is compacted, squeezing out water and air, then cemented by minerals such as calcite, quartz and hematite crystallizing in the pores between the grains. - The loop is not one-way. Any rock type can become any other: sedimentary rock can be uplifted and eroded again, and igneous rock can be buried and metamorphosed without passing through the other stages. #### Processes of the rock cycle and what each one does The processes a labeled rock cycle diagram is normally expected to name on its arrows, what each one does, and what it produces. This is the default label set unless you ask for a shorter one. - Melting — What happens: Rock deep in the crust or upper mantle is heated until it partly or fully melts | What it produces: Magma - Cooling and crystallization — What happens: Magma loses heat and its minerals crystallize — slowly underground, quickly at the surface | What it produces: Intrusive or extrusive igneous rock - Uplift — What happens: Mountain building raises buried rock, and erosion strips away the rock above it | What it produces: Rock exposed at the surface - Weathering — What happens: Rock is broken apart physically or altered chemically by water, air and living things | What it produces: Rock and mineral fragments, and dissolved ions - Erosion and transport — What happens: Water, ice, wind and gravity carry the weathered material away | What it produces: Moving sediment - Deposition — What happens: Sediment settles out in rivers, lakes, deserts and the ocean | What it produces: Layers of sediment - Compaction and cementation — What happens: Buried sediment is squeezed, and minerals growing in the pores glue the grains together (lithification) | What it produces: Sedimentary rock - Heat and pressure — What happens: Buried rock changes in the solid state — new minerals grow and grains may line up — without melting (metamorphism) | What it produces: Metamorphic rock Courses differ in how finely they split the arrows. Introductory worksheets often use three — melting, weathering and erosion, heat and pressure; earth science courses separate deposition, compaction and cementation, uplift, and intrusive from extrusive rock. Name the labels you need and only those are drawn. #### Igneous vs sedimentary vs metamorphic rock: what is the difference? Igneous rock crystallizes from molten magma or lava, sedimentary rock forms from sediment compacted and cemented at or near the surface, and metamorphic rock forms when existing rock is changed by heat and pressure without melting. How a rock formed shows in its texture: interlocking crystals, grains in layers, or aligned minerals. - How it forms — Igneous: Magma or lava cools and crystallizes | Sedimentary: Sediment is deposited, compacted and cemented | Metamorphic: Existing rock is altered by heat, pressure and fluids - Where it forms — Igneous: Underground (intrusive) or at the surface (extrusive) | Sedimentary: At or near the surface, in rivers, lakes, deserts and seas | Metamorphic: Deep in the crust, beneath mountain ranges or beside magma bodies - Typical texture — Igneous: Interlocking crystals — coarse if cooled slowly, fine if cooled fast | Sedimentary: Grains or fragments, often in layers | Metamorphic: Aligned minerals (foliated) or recrystallized grains (non-foliated) - Fossils — Igneous: None | Sedimentary: Common | Metamorphic: Rare, usually destroyed - Examples — Igneous: Granite, basalt, obsidian | Sedimentary: Sandstone, shale, limestone | Metamorphic: Slate, schist, gneiss, marble, quartzite - Next step in the cycle — Igneous: Weathering, or burial and metamorphism | Sedimentary: Burial and metamorphism, or uplift and erosion | Metamorphic: Melting into magma, or uplift and erosion Draw the three rock types around the loop with magma and sediment between them, then add the shortcuts: igneous rock weathered straight into sediment, sedimentary rock metamorphosed without melting, metamorphic rock uplifted and eroded. A cycle with only one-way arrows hides the point that any rock can become any other. #### Where are rock cycle diagrams used? Rock cycle diagrams are used mostly in earth science teaching — labeling worksheets, exam revision and lesson slides — and in geology courses, museum panels and field guides that explain how local rocks formed. What changes is the depth: three rock types for a first course, every process and both igneous settings for a university one. - School earth science: Labeling worksheets and revision sheets from middle school earth science (NGSS MS-ESS2-1) through high school geology and GCSE. Usually the labeled cycle, plus the same drawing blank for students to fill in. - University geology: Physical geology lectures that tie the cycle to plate tectonics: magma forming at subduction zones and spreading ridges, metamorphism beneath mountain ranges, sediment collecting in basins. - Exam revision: One-page summaries that name every arrow — which is how exam questions ask about the cycle: name the process at X, explain how a sedimentary rock becomes a metamorphic one. - Field guides and outreach: Panels for museums, parks and field trips that place the local rocks — a granite outcrop, a sandstone cliff, a marble quarry — on the cycle. #### Common questions about rock cycle diagrams **What should a labeled rock cycle diagram include?** The standard set is the three rock types — igneous, sedimentary and metamorphic — plus magma and sediment, joined by arrows labeled melting, cooling and crystallization, weathering and erosion, transport and deposition, compaction and cementation, heat and pressure, and uplift. That is the default — ask for fewer labels and only those are drawn. **What are the steps of the rock cycle?** Starting from magma: cooling and crystallization into igneous rock, uplift, weathering and erosion into sediment, deposition, compaction and cementation into sedimentary rock, burial under heat and pressure into metamorphic rock, and melting back into magma. Rock does not have to take every step in that order: igneous rock can be metamorphosed without ever becoming sediment, and metamorphic rock can be uplifted and eroded without melting. **What drives the rock cycle?** Two energy sources: Earth's internal heat and the Sun. Internal heat drives mantle convection and plate tectonics, which melt, bury, squeeze and uplift rock; the Sun powers the water cycle and the winds that weather rock at the surface and carry sediment away. On the Moon, with no mantle convection, atmosphere or liquid water, the rock cycle has all but stopped. **How does a sedimentary rock become a metamorphic rock?** It is buried deeper in the crust, where rising heat and pressure change it without melting it. New minerals grow, and under directed pressure they line up into layers called foliation: shale becomes slate, then schist, then gneiss. Limestone becomes marble and sandstone becomes quartzite. **Does rock have to melt to become metamorphic?** No — metamorphism happens in the solid state. Rock hot enough to melt becomes magma, and when magma cools the result is igneous rock, not metamorphic rock. Metamorphic rock records conditions just short of melting. **What is the difference between intrusive and extrusive igneous rock?** Intrusive igneous rock cools slowly underground, so its crystals grow large enough to see; extrusive igneous rock cools quickly at the surface, so its crystals are tiny or absent. Granite is the classic intrusive rock, basalt and obsidian the classic extrusive ones. **What is the difference between weathering and erosion?** Weathering breaks rock down where it sits; erosion carries the pieces away. Weathering is physical (frost wedging, for example) or chemical (minerals dissolving or altering); erosion is done by water, ice, wind and gravity, which then deposit the sediment somewhere else. **How long does the rock cycle take?** Usually tens to hundreds of millions of years for a full loop. One open geology textbook puts a conservative estimate of about 20 million years on each major step — burial, metamorphism, uplift, erosion — though some steps are far faster: lava can harden into rock within seconds. **Can I make a simple rock cycle drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: the three rock types in one loop with an arrow between each pair. Five labels or fewer usually covers a middle-school class. **How does the tool keep the rock cycle arrows in the right order?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — each stage in its true order around a closed loop, joined by arrows that name the process — with each label spelled exactly. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a rock cycle diagram from here in a worksheet or a field handout?** Yes — the rock cycle diagrams you generate are yours to use in earth science worksheets, field-trip handouts, slides and theses. Export goes up to 4K depending on the model, enough for a full-page printout. **Can I rename the processes or translate the rock cycle labels afterwards?** Yes. The canvas recognizes each label, so you can change 'cooling and crystallization' to 'solidification', translate the whole set, move an arrow's label or recolor the three rock types without regenerating the figure. #### Sources - The Rock Cycle — Physical Geology (Earle), section 3.1 — LibreTexts / BCcampus: https://geo.libretexts.org/Bookshelves/Geology/Physical_Geology_(Earle)/03%3A_Intrusive_Igneous_Rocks/3.01%3A_The_Rock_Cycle - Clastic Sedimentary Rocks — Physical Geology (Earle), section 6.1 — LibreTexts / BCcampus: https://geo.libretexts.org/Bookshelves/Geology/Physical_Geology_(Earle)/06%3A_Sediments_and_Sedimentary_Rocks/6.01%3A_Clastic_Sedimentary_Rocks - Classification of Metamorphic Rocks — Physical Geology (Earle), section 7.2 — LibreTexts / BCcampus: https://geo.libretexts.org/Bookshelves/Geology/Physical_Geology_(Earle)/07%3A_Metamorphism_and_Metamorphic_Rocks/7.02%3A_Classification_of_Metamorphic_Rocks --- ### Skeleton Diagram — Labeled Skeletal System, Blank Worksheet URL: https://scientificfigure.com/tools/skeletal-system-diagram Description: Make a labeled skeleton diagram in seconds: skull, spine, rib cage, pelvis, limbs, and the hand and foot bones. Free blank worksheet and answer key. #### What is a skeletal system diagram? A skeletal system diagram shows the bones of the human body in place, usually the whole skeleton in front view with the skull, spine, rib cage, pelvis and limb bones labeled. An adult has 206 bones. - An adult has 206 bones; a newborn has more. A baby is born with roughly 270 to 300 bones, some made entirely of cartilage, and many of them fuse during childhood and adolescence. - The skeleton has two divisions. The axial skeleton — 80 bones of the skull, vertebral column and thoracic cage — forms the body's central axis; the appendicular skeleton — 126 bones — is the limbs plus the shoulder and pelvic girdles that attach them. - The skeleton does more than hold the body up. It supports the body, gives the muscles levers to move, protects organs such as the brain, heart and lungs, makes blood cells in the red bone marrow, and stores calcium, phosphorus and fat. - Bones are sorted into five shapes. Long bones (femur, humerus), short bones (carpals, tarsals), flat bones (skull, sternum, ribs), irregular bones (vertebrae) and sesamoid bones (the patella). - The femur is the longest and strongest bone. The thigh bone accounts for about a quarter of a person's height; each arm and each leg holds 30 bones. #### Major bones of the skeleton and what each one does The bones a labeled skeletal system diagram is normally expected to name, where each sits, and what it does. This is the default label set unless you ask for a shorter one. - Skull (22 bones, including the mandible) — Where it is: Head | What it does: Encloses the brain and shapes the face; the mandible is the only skull bone that moves - Vertebral column (24 vertebrae, sacrum and coccyx) — Where it is: Back, from skull to pelvis | What it does: Supports the head and trunk and protects the spinal cord - Rib cage (12 pairs of ribs and the sternum) — Where it is: Chest | What it does: Protects the heart and lungs and moves with breathing - Clavicle and scapula — Where it is: Shoulder (pectoral girdle) | What it does: Attach each arm to the trunk - Humerus — Where it is: Upper arm | What it does: Runs from the shoulder joint to the elbow - Radius and ulna — Where it is: Forearm | What it does: Radius on the thumb side, ulna on the little-finger side - Carpals, metacarpals and phalanges — Where it is: Wrist, palm and fingers | What it does: 8 carpals, 5 metacarpals and 14 phalanges in each hand - Hip bones (pelvic girdle) — Where it is: Hips | What it does: Attach the legs to the vertebral column and carry the trunk's weight - Femur — Where it is: Thigh | What it does: Longest and strongest bone, from the hip joint to the knee - Patella — Where it is: Front of the knee | What it does: Kneecap, a sesamoid bone inside the thigh muscle's tendon - Tibia and fibula — Where it is: Lower leg | What it does: Tibia on the inner side bears the weight; fibula is the thin outer bone - Tarsals, metatarsals and phalanges — Where it is: Ankle, foot and toes | What it does: 7 tarsals, 5 metatarsals and 14 phalanges in each foot Courses differ in how many bones they expect. Introductory worksheets often stop at the skull, rib cage, spine, pelvis and femur; anatomy courses add both girdles, every long bone and the hand and foot groups, sometimes each carpal by name. Name the labels you need and only those are drawn. #### Axial vs appendicular skeleton: what is the difference? The axial skeleton is the 80 bones along the body's central axis — skull, vertebral column and thoracic cage — and mainly protects the brain, spinal cord, heart and lungs; the appendicular skeleton is the 126 bones of the arms and legs plus the girdles that attach them, and mainly moves the body. - Number of bones (adult) — Axial skeleton: 80 | Appendicular skeleton: 126 - Main parts — Axial skeleton: Skull, hyoid, middle-ear ossicles, vertebral column, thoracic cage | Appendicular skeleton: Shoulder girdles, arms, pelvic girdle, legs - Position — Axial skeleton: Along the body's vertical midline | Appendicular skeleton: Hanging from the axis on either side - Main role — Axial skeleton: Protection and support of the head and trunk | Appendicular skeleton: Movement, walking and handling objects - Protects — Axial skeleton: Brain, spinal cord, heart and lungs | Appendicular skeleton: Mainly movement; the pelvic girdle helps shelter the pelvic organs - Example bones — Axial skeleton: Skull, vertebrae, ribs, sternum, sacrum | Appendicular skeleton: Clavicle, scapula, humerus, hip bone, femur, tibia When the two divisions are colored differently, check the girdles first: the clavicles, scapulae and hip bones belong to the appendicular skeleton even though they sit on the trunk, while the sacrum between the hip bones is axial. A diagram that colors the whole pelvis with the spine has the boundary wrong. #### Where are skeletal system diagrams used? Skeletal system diagrams are used mostly in biology and anatomy teaching — labeling worksheets, exam revision and lecture slides — and in nursing, physiotherapy and sports-science courses that need every bone named correctly. What changes is the depth: five bones for a first course, every long bone and the hand and foot groups for an anatomy one. - School biology: Labeling worksheets and revision sheets from middle school through GCSE, AP Biology and IB. Usually the labeled front-view skeleton, plus the same drawing blank for students to fill in. - Anatomy and health courses: Nursing, physiotherapy, kinesiology and pre-med courses that expect every long bone, both girdles and the carpal and tarsal groups, often split into axial and appendicular. - Exam revision: One-page summaries that put each bone in place — which is how practical exams ask about them: name the bone at X, say whether it is axial or appendicular. - Patient and sports education: Handouts that show where an injury sits — a fractured radius, a stress fracture in the tibia — with the bone highlighted on the whole skeleton. #### Common questions about skeletal system diagrams **What should a labeled skeletal system diagram include?** The standard set is the skull, mandible, clavicle, scapula, sternum, ribs, vertebral column, humerus, radius, ulna, carpals, metacarpals, phalanges, pelvis, sacrum, femur, patella, tibia, fibula, tarsals and metatarsals. That is the default — ask for fewer labels and only those are drawn. **Can I get a blank skeletal system diagram for students to label?** Yes — the blank skeleton on this page is free to view, and you can ask for your own. Every bone name, from the skull and clavicle to the tibia and tarsals, becomes an empty answer line; the labeled skeleton above it is the matching answer key. **How many bones are in the human body?** An adult skeleton has 206 bones: 80 in the axial skeleton and 126 in the appendicular skeleton. A newborn has roughly 270 to 300, some still made of cartilage; many fuse as the child grows, which is why the adult count is lower. **What are the functions of the skeletal system?** Support, movement, protection, blood cell production and storage. The skeleton holds the body up against gravity, gives the muscles levers to pull on, shields the brain, heart and lungs, makes blood cells in the red bone marrow, and stores calcium, phosphorus and fat. **What is the difference between the axial and appendicular skeleton?** The axial skeleton is the 80 bones of the skull, vertebral column and thoracic cage along the body's midline; the appendicular skeleton is the 126 bones of the limbs and the girdles that attach them. The first mainly protects and supports; the second mainly moves. **What is the longest bone in the body?** The femur, or thigh bone — the longest and strongest bone in the body, about a quarter of a person's height. Its rounded head fits into the hip bone to form the hip joint, and its lower end meets the tibia and the patella at the knee. **How many bones are in the hand and the foot?** Each hand has 27 bones — 8 carpals, 5 metacarpals and 14 phalanges — and each foot has 26: 7 tarsals, 5 metatarsals and 14 phalanges. On a whole-skeleton diagram these are usually labeled as groups rather than bone by bone. **What are the five types of bones?** Long, short, flat, irregular and sesamoid. Long bones such as the femur act as levers; short bones (carpals, tarsals) give stability; flat bones (skull, sternum, ribs) protect organs; irregular bones (vertebrae) have complex shapes; sesamoid bones, like the patella, form inside tendons. **Can I make a simple skeleton drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: the skull, rib cage, spine, pelvis and femur. Five labels or fewer usually covers a middle-school class. **How does the tool keep every bone in the right position?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — every bone in its true position and relative proportion — with each label spelled exactly and set on a straight leader line. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a skeleton diagram from here in an anatomy class or a handout?** Yes — the skeleton diagrams you generate are yours to use in anatomy worksheets, PE and first-aid handouts, slides and theses. Export goes up to 4K depending on the model, enough for a poster-size print. **Can I switch between common and anatomical bone names afterwards?** Yes. The canvas recognizes each label, so you can change 'clavicle' to 'collarbone' or 'patella' to 'kneecap', translate the set, move a crowded leader line or recolor a bone group without regenerating the figure. #### Sources - Bone Classification — Anatomy and Physiology 2e, section 6.2 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/6-2-bone-classification - Divisions of the Skeletal System — Anatomy and Physiology 2e, section 7.1 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/7-1-divisions-of-the-skeletal-system - Bones of the Lower Limb — Anatomy and Physiology 2e, section 8.4 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/8-4-bones-of-the-lower-limb --- ### Chloroplast Diagram — Labeled & Blank, Free Maker URL: https://scientificfigure.com/tools/chloroplast-diagram Description: Make a labeled chloroplast diagram in seconds: outer and inner membrane, stroma, thylakoids and grana in cross-section. Free blank worksheet and answer key. #### What is a chloroplast diagram? A chloroplast diagram shows the organelle of photosynthesis in cross-section: a double-membrane envelope around the fluid stroma, with thylakoids stacked into grana. Light is captured on the thylakoid membranes; the Calvin cycle builds sugar in the stroma. - A chloroplast has three membrane systems. The outer and inner membranes form the envelope; the thylakoid membranes inside, stacked into grana, form a third and enclose the thylakoid lumen. - The two stages of photosynthesis happen in different places. The light-dependent reactions run on the thylakoid membranes and make ATP and NADPH; the Calvin cycle runs in the stroma and uses them to build sugar from carbon dioxide. - Chlorophyll sits in the thylakoid membranes. Each photosystem is served by a light-harvesting complex of 300 to 400 chlorophyll a and b molecules plus carotenoids, which pass the energy of absorbed light to a reaction center. - Chloroplasts carry their own genome. Like mitochondria they have their own DNA — a single circular chromosome — and their own ribosomes, a legacy of their descent from free-living cyanobacteria. - Carbon dioxide reaches the chloroplast from outside the leaf. It enters through the stomata, diffuses to the mesophyll cells and on into the stroma, where it is fixed. #### Parts of a chloroplast and what each one does The structures a labeled chloroplast diagram is normally expected to show, what each one does, and where it sits. This is the default label set unless you ask for a shorter one. - Outer membrane — What it does: Outer layer of the double-membrane envelope | Where to draw it: The outermost boundary of the organelle - Intermembrane space — What it does: Narrow gap between the two envelope membranes | Where to draw it: A thin band between the outer and inner membrane - Inner membrane — What it does: Inner layer of the envelope; controls what passes into the stroma | Where to draw it: Just inside the outer membrane - Stroma — What it does: Fluid where the Calvin cycle builds sugar from carbon dioxide | Where to draw it: Filling the space inside the inner membrane - Thylakoid — What it does: Flattened membrane sac carrying chlorophyll and the light-dependent reactions | Where to draw it: Throughout the stroma, mostly in stacks - Granum (plural grana) — What it does: A stack of thylakoids | Where to draw it: Several stacks spread across the stroma - Thylakoid lumen — What it does: Space inside each thylakoid, where protons build up to drive ATP synthase | Where to draw it: Inside every thylakoid disc - Stroma lamellae — What it does: Unstacked thylakoids linking one granum to the next | Where to draw it: Thin sheets running between the grana - Chloroplast DNA — What it does: The chloroplast's own genome, a single circular chromosome | Where to draw it: Small loops in the stroma - Ribosomes — What it does: Make the proteins coded by chloroplast DNA | Where to draw it: Small dots in the stroma - Starch grain — What it does: Stores sugar made by photosynthesis | Where to draw it: Oval granules in the stroma Courses differ in how many of these they expect. Introductory worksheets often stop at the outer membrane, inner membrane, stroma, thylakoid and granum; advanced courses add the lumen, stroma lamellae, chloroplast DNA, ribosomes and starch. Name the labels you need and only those are drawn. #### Light-dependent reactions vs Calvin cycle: what is the difference? The light-dependent reactions run on the thylakoid membranes, use light to split water, release oxygen and make ATP and NADPH; the Calvin cycle runs in the stroma and spends that ATP and NADPH to fix carbon dioxide into sugar. The Calvin cycle needs no light directly, but it stops once the light reactions stop supplying it. - Where in the chloroplast — Light-dependent reactions: Thylakoid membranes | Calvin cycle: Stroma - Uses light directly — Light-dependent reactions: Yes | Calvin cycle: No, but depends on the products of the light reactions - Takes in — Light-dependent reactions: Light, water, ADP and NADP⁺ | Calvin cycle: Carbon dioxide, ATP and NADPH - Gives out — Light-dependent reactions: Oxygen, ATP and NADPH | Calvin cycle: Sugar (G3P), ADP and NADP⁺ - Key players — Light-dependent reactions: Photosystem II, electron transport chain, photosystem I, ATP synthase | Calvin cycle: RuBisCO and RuBP - Other names — Light-dependent reactions: Light reactions | Calvin cycle: Light-independent reactions; the outdated name is dark reaction Draw ATP and NADPH moving from the thylakoids into the stroma, and ADP and NADP⁺ moving back: the two stages form a loop. A diagram that puts the Calvin cycle outside the chloroplast, or calls it a dark reaction that happens only at night, has the model wrong. #### Where are chloroplast diagrams used? Chloroplast diagrams are used mostly in biology teaching — labeling worksheets, photosynthesis lessons and exam revision — and as schematic panels in plant science talks and papers. What changes is the depth: five labels for a first course, the lumen, stroma lamellae, photosystems and ATP synthase for a university one. - School biology: Labeling worksheets and revision sheets from middle school through GCSE, A-level, AP Biology and IB, usually next to the plant cell. The labeled cross-section, plus the same drawing blank for students. - Photosynthesis lessons: The chloroplast as the stage for both halves of photosynthesis: light reactions on the thylakoids, the Calvin cycle in the stroma, ATP and NADPH passing between them. - Exam revision: One-page summaries that tie each structure to its job — which is how exam questions ask about them: name the site of the Calvin cycle, explain why stacked grana give a large membrane surface. - Research figures: Schematic panels for work on photosynthetic efficiency, chloroplast genomes or protein import, with the compartment under study marked on the organelle. #### Common questions about chloroplast diagrams **What should a labeled chloroplast diagram include?** The standard set is the outer membrane, intermembrane space, inner membrane, stroma, thylakoids, grana, thylakoid lumen, stroma lamellae, chloroplast DNA, ribosomes and starch grains. That is the default — ask for fewer labels and only those are drawn. **Can I get a blank chloroplast diagram for students to label?** Yes — the blank chloroplast on this page is free to view, and you can ask for your own. The outer and inner membranes, stroma, thylakoids, grana and the rest become empty answer lines; the labeled cross-section above it is the matching answer key. **What is the function of the chloroplast?** The chloroplast carries out photosynthesis: it captures light energy and stores it in sugar built from carbon dioxide and water, releasing oxygen. It also makes some of its own proteins from its own DNA, and in many plants stores the sugar it makes as starch. **What is the difference between a thylakoid and a granum?** A thylakoid is a single flattened membrane sac; a granum is a stack of thylakoids. The stacks are joined by unstacked thylakoids called stroma lamellae, so the thylakoids form one interconnected membrane system. **What is the difference between stroma and stoma?** Stroma is the fluid inside a chloroplast, where the Calvin cycle runs; a stoma (plural stomata) is a pore in the leaf surface that lets carbon dioxide in and oxygen and water vapor out. **Where does the Calvin cycle take place?** In the stroma of the chloroplast. There the enzyme RuBisCO fixes carbon dioxide onto RuBP, and ATP and NADPH from the thylakoid membranes power the reduction and regeneration steps. Three turns of the cycle make one G3P; six make one glucose. **What is the difference between a chloroplast and a mitochondrion?** A chloroplast captures light energy to build sugar; a mitochondrion breaks sugar down to make ATP. Both have a double membrane and their own DNA and ribosomes, and both descend from bacteria. Plant cells have both; animal cells have only mitochondria. **Why are chloroplasts green?** Because chlorophyll in the thylakoid membranes absorbs mostly blue and red light and reflects green. Chloroplasts also hold yellow and orange carotenoids, which show in autumn leaves once the chlorophyll breaks down. **Can I make a simple chloroplast drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: the outer membrane, inner membrane, stroma, thylakoids and a granum. Five labels or fewer usually covers a middle-school class. **How does the tool keep the chloroplast's structures in the right place?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — every structure in its true position and relative proportion, nothing that does not belong in a chloroplast — with each label spelled exactly and set on a straight leader line. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a chloroplast diagram from here in a lesson or a thesis?** Yes — the chloroplast diagrams you generate are yours to use in photosynthesis lessons, revision sheets, slides and thesis figures. Export goes up to 4K depending on the model. **Can I rename or translate the chloroplast labels afterwards?** Yes. The canvas recognizes each label, so you can swap 'stroma lamellae' for 'stroma thylakoids', translate the set, move a leader line off a granum or recolor the thylakoids without regenerating the figure. #### Sources - The Light-Dependent Reactions of Photosynthesis — Biology 2e, section 8.2 — OpenStax: https://openstax.org/books/biology-2e/pages/8-2-the-light-dependent-reactions-of-photosynthesis - Using Light Energy to Make Organic Molecules — Biology 2e, section 8.3 — OpenStax: https://openstax.org/books/biology-2e/pages/8-3-using-light-energy-to-make-organic-molecules - Eukaryotic Cells — Biology 2e, section 4.3 — OpenStax: https://openstax.org/books/biology-2e/pages/4-3-eukaryotic-cells --- ### Meiosis Diagram — Labeled Stages of Meiosis 1 & 2, Free URL: https://scientificfigure.com/tools/meiosis-diagram Description: Make a labeled meiosis diagram in seconds: every stage of meiosis I and II, crossing over at the chiasmata, four haploid cells, and mitosis vs meiosis. #### What is a meiosis diagram? A meiosis diagram shows one diploid cell dividing twice into four haploid cells: homologous chromosomes pair, cross over and separate in meiosis I, and sister chromatids separate in meiosis II. Each stage is drawn in order. - One round of DNA replication, two divisions. Chromosomes are copied once, in the S phase before meiosis, and the cell then divides twice, halving the chromosome number: a human cell goes from 46 chromosomes to 23. - Meiosis I separates homologous chromosomes; meiosis II separates sister chromatids. After meiosis I each cell is already haploid, though every chromosome still has two chromatids; meiosis II splits them, much as mitosis does. - Crossing over happens in prophase I. Homologous chromosomes pair tightly (synapsis) and non-sister chromatids exchange segments; the crossover points show as chiasmata, at least one per chromosome. - Independent assortment multiplies the variety. Each homologous pair lines up at random in metaphase I, so a human cell with 23 pairs can produce over 8 million (2²³) chromosome combinations before crossing over is counted. - The four products are genetically different. Crossing over and independent assortment make every haploid cell unique, unlike the two identical cells mitosis produces. #### Stages of meiosis and what happens in each The stages a labeled meiosis diagram is normally expected to show, what happens to the chromosomes in each, and what to draw. This is the default label set unless you ask for a shorter one. - Interphase (before meiosis) — What happens: DNA is replicated; each chromosome becomes two sister chromatids | What to draw: One diploid cell with an intact nucleus - Prophase I — What happens: Chromosomes condense; homologous chromosomes pair (synapsis) and cross over | What to draw: Paired homologs joined at chiasmata, nuclear envelope breaking down - Metaphase I — What happens: Homologous pairs line up at the metaphase plate, each in random orientation | What to draw: Pairs side by side across the equator, spindle fibers from both poles - Anaphase I — What happens: Homologous chromosomes are pulled to opposite poles; sister chromatids stay together | What to draw: Whole X-shaped chromosomes moving apart - Telophase I and cytokinesis — What happens: Two haploid cells form, each chromosome still made of two chromatids | What to draw: Two cells, each with half the chromosomes - Prophase II — What happens: Chromosomes condense again and new spindles form, with no DNA replication | What to draw: Two cells, each with a new spindle - Metaphase II — What happens: Chromosomes line up singly at the plate in each cell | What to draw: One row of X-shaped chromosomes per cell - Anaphase II — What happens: Sister chromatids separate and move to opposite poles | What to draw: Single chromatids moving apart in both cells - Telophase II and cytokinesis — What happens: Nuclei re-form and both cells divide | What to draw: Four haploid cells, each genetically different Courses differ in how many stages they expect. Introductory worksheets often show meiosis I and II as two steps ending in four cells; advanced courses add prometaphase, interkinesis, the synaptonemal complex and the substages of prophase I. Name the stages you need and only those are drawn. #### Mitosis vs meiosis: what is the difference? Mitosis is one division that makes two cells genetically identical to the parent, with the same chromosome number; meiosis is two divisions that make four genetically different cells with half the chromosome number. Mitosis builds and repairs the body; meiosis makes the haploid cells of sexual reproduction — eggs and sperm in animals. - Number of divisions — Mitosis: One | Meiosis: Two - Cells produced — Mitosis: Two | Meiosis: Four - Chromosome number — Mitosis: Same as the parent | Meiosis: Halved, diploid to haploid - Genetic makeup — Mitosis: Identical to the parent | Meiosis: Different from the parent and from each other - Homologous chromosomes pair up — Mitosis: No | Meiosis: Yes, in prophase I - Crossing over — Mitosis: No | Meiosis: Yes, in prophase I - What lines up at the metaphase plate — Mitosis: Single chromosomes | Meiosis: Homologous pairs in metaphase I, single chromosomes in metaphase II - Purpose — Mitosis: Growth, repair and asexual reproduction | Meiosis: Gametes or spores for sexual reproduction - Where in the human body — Mitosis: Body (somatic) cells | Meiosis: Ovaries and testes Draw meiosis I with pairs of X-shaped chromosomes and meiosis II with single ones, and keep the maternal and paternal colors through every stage so crossing over shows as swapped segments. A diagram that pairs homologs in mitosis, or splits sister chromatids in anaphase I, is the error to check for first. #### Where are meiosis diagrams used? Meiosis diagrams are used mostly in biology teaching — labeling worksheets, genetics lessons and exam revision — and as schematic panels in talks and papers on fertility, chromosome errors and breeding. What changes is the depth: two divisions and four cells for a first course, every stage with crossing over and chiasmata for a university one. - School biology: Labeling worksheets and revision sheets from middle school through GCSE, A-level, AP Biology and IB. Usually the stages in order, plus the same drawing blank for students to fill in. - Genetics lessons: Diagrams that tie meiosis to inheritance: crossing over and independent assortment explaining why siblings differ, and Mendel's laws following from how chromosomes separate. - Exam revision: One-page comparisons of mitosis and meiosis, and of meiosis I and II — which is how exam questions ask about them: identify the stage, say whether the cell is haploid or diploid. - Medical and research figures: Schematic panels on nondisjunction and aneuploidy — how a failed separation in meiosis I or II leads to a trisomy such as Down syndrome — or on meiosis in plant and animal breeding. #### Common questions about meiosis diagrams **What should a labeled meiosis diagram include?** The standard set is prophase I with crossing over, metaphase I, anaphase I and telophase I, then prophase II, metaphase II, anaphase II and telophase II, ending in four haploid cells — with the homologous chromosomes, sister chromatids, chiasmata, spindle fibers and metaphase plate labeled. That is the default — ask for fewer labels and only those are drawn. **What is the difference between spermatogenesis and oogenesis?** Both are meiosis, but spermatogenesis turns each primary spermatocyte into four sperm, while oogenesis turns each primary oocyte into one egg and smaller polar bodies. Spermatogenesis runs continuously from puberty; oogenesis pauses twice, in prophase I from before birth and in metaphase II until fertilization. **What are the stages of meiosis in order?** Prophase I, metaphase I, anaphase I and telophase I, then prophase II, metaphase II, anaphase II and telophase II. Many textbooks also name prometaphase I and II, and some species pass through a short interkinesis between the two divisions, with no DNA replication. **What is the difference between meiosis I and meiosis II?** Meiosis I separates homologous chromosomes and halves the chromosome number; meiosis II separates sister chromatids and keeps the number the same. Crossing over and independent assortment both happen in meiosis I; meiosis II works much like mitosis in a haploid cell. **What is crossing over, and when does it happen?** Crossing over is the exchange of segments between non-sister chromatids of a homologous pair, during prophase I. A protein lattice, the synaptonemal complex, holds the pair together while the DNA is cut and rejoined; the crossover points appear as chiasmata, which keep the pair linked until anaphase I. **Why does meiosis produce genetic variation?** Because of crossing over in prophase I and the random orientation of homologous pairs in metaphase I. With 23 chromosome pairs, a human can make over 8 million chromosome combinations from independent assortment alone; crossing over multiplies that further. **What is the difference between haploid and diploid?** A diploid cell has two sets of chromosomes, one from each parent; a haploid cell has one set. In humans, body cells are diploid with 46 chromosomes (2n = 46) and eggs and sperm are haploid with 23 (n = 23); fertilization restores the diploid number. **What happens if chromosomes fail to separate in meiosis?** This is nondisjunction, and it gives gametes an extra or a missing chromosome. If it happens in meiosis I, all four gametes are abnormal; in meiosis II, two of the four are. A fertilized egg with an extra chromosome 21 — trisomy 21 — develops Down syndrome. **Can I make a simple meiosis drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: one parent cell dividing twice into four sex cells, each with half the chromosomes. Five labels or fewer usually covers a middle-school class. **How does the tool keep the stages of meiosis in the right order?** The subject brief is built in. Every render is instructed to follow the standard textbook sequence — each stage drawn in its true order and joined to the next by an arrow — with each stage name spelled exactly. Check the chromosome counts and labels against your course before printing; the canvas lets you correct any label in place. **Can I use a meiosis diagram from here in a genetics lesson or a report?** Yes — the meiosis diagrams you generate are yours to use in genetics worksheets, revision cards, slides and theses. Export goes up to 4K depending on the model. **Can I rename the stages or translate the meiosis labels afterwards?** Yes. The canvas recognizes each label, so you can change 'chiasmata' to 'crossing over', translate the stage names, move a label between cells or recolor the two chromosome sets without regenerating the figure. #### Sources - The Process of Meiosis — Biology 2e, section 11.1 — OpenStax: https://openstax.org/books/biology-2e/pages/11-1-the-process-of-meiosis - Chromosomal Basis of Inherited Disorders — Biology 2e, section 13.2 — OpenStax: https://openstax.org/books/biology-2e/pages/13-2-chromosomal-basis-of-inherited-disorders --- ### Molecular Orbital Diagram Generator: O₂, N₂ & CO MO Diagrams URL: https://scientificfigure.com/tools/molecular-orbital-diagram-generator Description: Make a molecular orbital diagram for O₂, N₂, CO or any diatomic: σ and π orbitals in the right order, electrons filled, bond order and magnetism. Free to start. #### What is a molecular orbital diagram? A molecular orbital (MO) diagram is an energy-level chart of a molecule: the atomic orbitals of each atom sit in the two outer columns, the molecular orbitals they combine into sit in the centre — bonding orbitals (σ, π) lower, antibonding orbitals (σ*, π*) higher — and the electrons are filled in from the bottom up. Counting them gives the bond order, (bonding − antibonding) / 2, and any unpaired electrons show that the molecule is paramagnetic. - The order of σ2p and π2p flips between N₂ and O₂. From Li₂ to N₂, s–p mixing pushes σ2p above the two π2p orbitals; in O₂ and F₂ the 2s–2p gap is too wide for that, and σ2p sits below π2p. An O₂ diagram drawn in the N₂ order is the most common error. - Bond order = (bonding electrons − antibonding electrons) / 2. N₂ has 8 bonding and 2 antibonding valence electrons, bond order 3; O₂ has 8 and 4, bond order 2; He₂ would have 2 and 2, bond order 0 — so it does not form. - MO theory explains why O₂ is magnetic. Its last two electrons go one each into the two π*2p orbitals of equal energy (Hund's rule), leaving two unpaired electrons — measurable on a magnetic balance, and invisible in a Lewis structure. - As many orbitals come out as go in. Two 1s orbitals give σ1s and σ*1s; two sets of three 2p orbitals give σ2p, two π2p, two π*2p and σ*2p — six in, six out. - In a heteronuclear molecule the two columns are uneven. For CO, NO or HF the more electronegative atom's orbitals sit lower, and the bonding orbitals lie closer to it in energy; NO, with 11 valence electrons, has a bond order of (8 − 3) / 2 = 2.5. #### MO diagrams of the second-period diatomic molecules Valence electrons, orbital order, bond order and magnetism for every homonuclear diatomic from Li₂ to Ne₂, as OpenStax Chemistry 2e lists them. The orbital-order column is the one to check first on any diagram. - Li₂ — Valence electrons: 2 | Order of the 2p orbitals: π2p below σ2p (s–p mixing) | Bond order: 1 | Magnetism: Diamagnetic - Be₂ — Valence electrons: 4 | Order of the 2p orbitals: π2p below σ2p (s–p mixing) | Bond order: 0 — does not form | Magnetism: — - B₂ — Valence electrons: 6 | Order of the 2p orbitals: π2p below σ2p (s–p mixing) | Bond order: 1 | Magnetism: Paramagnetic, 2 unpaired π electrons - C₂ — Valence electrons: 8 | Order of the 2p orbitals: π2p below σ2p (s–p mixing) | Bond order: 2 | Magnetism: Diamagnetic - N₂ — Valence electrons: 10 | Order of the 2p orbitals: π2p below σ2p (s–p mixing) | Bond order: 3 | Magnetism: Diamagnetic - O₂ — Valence electrons: 12 | Order of the 2p orbitals: σ2p below π2p | Bond order: 2 | Magnetism: Paramagnetic, 2 unpaired π* electrons - F₂ — Valence electrons: 14 | Order of the 2p orbitals: σ2p below π2p | Bond order: 1 | Magnetism: Diamagnetic - Ne₂ — Valence electrons: 16 | Order of the 2p orbitals: σ2p below π2p | Bond order: 0 — does not form | Magnetism: — Only the 2p order moves. σ2s and σ*2s sit at the bottom and σ*2p at the top in every one of these; what changes is whether σ2p lies above the two π2p orbitals (Li₂ to N₂) or below them (O₂ to Ne₂). Name the molecule and the diagram is drawn in its order. #### Bonding vs antibonding molecular orbitals: what is the difference? A bonding orbital (σ, π) builds up electron density between the two nuclei and lies lower in energy than the atomic orbitals that formed it; an antibonding orbital (σ*, π*) has a node between the nuclei and lies higher. Electrons in bonding orbitals hold the atoms together; electrons in antibonding orbitals cancel part of that out. - Symbol — Bonding orbital: σ, π | Antibonding orbital: σ*, π* — the asterisk marks antibonding - Energy — Bonding orbital: Lower than the atomic orbitals it comes from | Antibonding orbital: Higher than the atomic orbitals it comes from - Electron density between the nuclei — Bonding orbital: Increased — the waves add up | Antibonding orbital: Zero at a nodal plane — the waves cancel - Effect on the bond — Bonding orbital: Each electron adds ½ to the bond order | Antibonding orbital: Each electron takes ½ off the bond order - Place on the diagram — Bonding orbital: Below the atomic orbital lines | Antibonding orbital: Above the atomic orbital lines - In O₂ — Bonding orbital: σ2s, σ2p, two π2p — 8 electrons | Antibonding orbital: σ*2s, two π*2p — 4 electrons; σ*2p empty Check the half-arrows first: paired arrows point opposite ways, orbitals of equal energy take one electron each before any pairing (Hund's rule), and no line holds more than two. O₂'s two π* electrons drawn as a pair is the error to look for. #### Where are molecular orbital diagrams used? Molecular orbital diagrams are used mostly in general and inorganic chemistry teaching — homework, exam revision and lecture slides — and in research talks on bonding, spectroscopy and materials. What changes is the molecule: H₂ and He₂ in a first course, the second-period diatomics and CO later, frontier orbitals in organic and materials chemistry. - General chemistry: AP Chemistry, A-level and first-year university courses: MO diagrams of H₂, He₂ and the second-period diatomics, with the bond order and the magnetism read off the filled diagram. - Inorganic chemistry: Heteronuclear diatomics such as CO, NO and HF, where the more electronegative atom's orbitals sit lower — the groundwork for metal–carbonyl bonding and ligand field theory. - Exam revision: One-page comparisons such as N₂ against O₂ that show the orbital-order swap — the most tested point in the topic — beside their bond orders and unpaired electrons. - Research and teaching figures: Schematic HOMO and LUMO energy diagrams for talks and papers in photochemistry, organic electronics and catalysis, where the gap between the two sets what a molecule absorbs. #### Common questions about molecular orbital diagrams **What should a labeled molecular orbital diagram include?** The atomic orbitals of each atom in the outer columns, every molecular orbital in the centre with its name (σ2s, σ*2s, σ2p, π2p, π*2p, σ*2p), dashed lines joining them, the electrons as half-arrows and an energy axis pointing up. Most courses also want the bond order and whether the molecule is paramagnetic or diamagnetic written beside it. **Why do He₂, Be₂ and Ne₂ not exist?** Their MO diagrams have as many electrons in antibonding orbitals as in bonding ones, so the bond order is 0: He₂ has 2 and 2, Be₂ has 2 and 2 in the 2s orbitals, Ne₂ has 8 and 8. With no net bond, two separate atoms are lower in energy than the pair. Only very weakly bound pairs have been detected, in cold gas-phase experiments; none forms a stable molecule. **Why is O₂ paramagnetic?** Because its last two valence electrons sit one each in the two π*2p orbitals, unpaired. The two orbitals have the same energy, so Hund's rule places one electron in each before any pairing. A Lewis structure pairs every electron in O₂ and cannot explain why liquid oxygen clings to a magnet; the MO diagram can. **Why do N₂ and O₂ have different orbital orders?** Because of s–p mixing. From Li₂ to N₂ the 2s and 2p orbitals are close in energy, their σ combinations mix, and σ2p is pushed up above the two π2p orbitals. In O₂ and F₂ the 2s–2p gap is wider, the mixing is too weak to change the order, and σ2p stays below π2p. **How do you calculate bond order from a molecular orbital diagram?** Count the electrons in bonding orbitals and in antibonding orbitals, subtract, and divide by two. For O₂: 8 bonding (σ2s, σ2p, two π2p) minus 4 antibonding (σ*2s, two π*2p) gives (8 − 4) / 2 = 2 — the double bond of its Lewis structure. A bond order of 0, as for He₂ or Ne₂, means the molecule does not form. **How do you draw an MO diagram for a heteronuclear molecule like CO or HF?** Put the more electronegative atom's orbitals lower, in its own column. In CO, oxygen's 2s and 2p sit below carbon's, and its 10 valence electrons — the same count as N₂ — give a bond order of 3. In HF, the hydrogen 1s combines with one fluorine 2p orbital into a σ and σ* pair, while fluorine's 2s and its other two 2p orbitals stay nonbonding: bond order 1. **What is the difference between an MO diagram and a Lewis structure?** A Lewis structure draws bonds as shared electron pairs between two atoms; an MO diagram spreads the electrons over orbitals of the whole molecule, sorted by energy. Both usually give the same bond order, but only the MO diagram shows unpaired electrons like O₂'s or a fractional bond order like the 2.5 of NO. The Lewis structure generator on this site draws the other one. **Is a molecular orbital diagram the same as an orbital diagram?** No — an orbital diagram shows one atom's electron configuration, a molecular orbital diagram shows two atoms' orbitals combining. An orbital diagram draws 1s, 2s, 2p and so on as boxes or lines with up to two arrows each; the MO diagram puts two of those in the outer columns and the molecule's orbitals between them. Ask for either one here. **Can I make MO diagrams for molecules with more than two atoms?** Yes, as qualitative diagrams — the π system of benzene, the orbitals of water, a HOMO–LUMO gap. The levels are drawn in their textbook order, not at computed energies; if you have values from a quantum chemistry program, give them in the request and the diagram follows your numbers. #### Sources - Molecular Orbital Theory — Chemistry 2e, section 8.4 — OpenStax: https://openstax.org/books/chemistry-2e/pages/8-4-molecular-orbital-theory - Electronic Structure of Atoms (Electron Configurations) — Chemistry 2e, section 6.4 — OpenStax: https://openstax.org/books/chemistry-2e/pages/6-4-electronic-structure-of-atoms-electron-configurations - Molecular-Orbital Theory Also Applies to Heteronuclear Diatomic Molecules — Physical Chemistry, section 9.12 — LibreTexts: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Physical_Chemistry_(LibreTexts)/09:_Chemical_Bonding_in_Diatomic_Molecules/9.12:_Molecular-Orbital_Theory_Also_Applies_to_Heteronuclear_Diatomic_Molecules --- ### Bohr Model Diagram Generator — Bohr–Rutherford Diagram, Free URL: https://scientificfigure.com/tools/bohr-model-diagram Description: Make a Bohr model diagram of any element, from hydrogen and carbon to sodium and calcium: protons and neutrons in the nucleus, electrons on 2, 8, 8 shells. #### What is a Bohr model diagram? A Bohr model diagram draws an atom as a small nucleus — its protons and neutrons counted inside — with the electrons on concentric circular shells around it, filled from the innermost shell outward. The number of protons is the atomic number, protons plus neutrons is the mass number, and the electrons on the outer shell are the valence electrons that decide how the element bonds. - Niels Bohr proposed it in 1913 for the hydrogen atom. Electrons move only in allowed orbits of fixed energy and give out or take in light only when they jump between them — which reproduced the hydrogen line spectrum and the Rydberg constant. - A shell holds at most 2n² electrons — 2, 8, 18, 32. That is 2 in the first shell, 8 in the second and 18 in the third. - School diagrams fill the third shell only to 8 for the first 20 elements. After argon the next electrons go into 4s, which lies below 3d, so potassium is drawn 2, 8, 8, 1 and calcium 2, 8, 8, 2 — although the third shell could hold 18. - Neutrons = mass number − atomic number. Sodium-23 has 11 protons and 23 − 11 = 12 neutrons; carbon-12 has 6 of each. A neutral atom has as many electrons as protons. - It is a teaching model, not the modern picture. Fixed orbits cannot explain atoms with more than one electron; the quantum mechanical model replaced them with orbitals, and molecular orbital theory carries that on to chemical bonds. #### Bohr model electron arrangements of the first 20 elements Protons, neutrons in the most common isotope, and electrons per shell for hydrogen to calcium — the numbers a Bohr model diagram of each element is checked against. - Hydrogen (H-1) — Protons: 1 | Neutrons: 0 | Electrons per shell: 1 - Helium (He-4) — Protons: 2 | Neutrons: 2 | Electrons per shell: 2 - Lithium (Li-7) — Protons: 3 | Neutrons: 4 | Electrons per shell: 2, 1 - Beryllium (Be-9) — Protons: 4 | Neutrons: 5 | Electrons per shell: 2, 2 - Boron (B-11) — Protons: 5 | Neutrons: 6 | Electrons per shell: 2, 3 - Carbon (C-12) — Protons: 6 | Neutrons: 6 | Electrons per shell: 2, 4 - Nitrogen (N-14) — Protons: 7 | Neutrons: 7 | Electrons per shell: 2, 5 - Oxygen (O-16) — Protons: 8 | Neutrons: 8 | Electrons per shell: 2, 6 - Fluorine (F-19) — Protons: 9 | Neutrons: 10 | Electrons per shell: 2, 7 - Neon (Ne-20) — Protons: 10 | Neutrons: 10 | Electrons per shell: 2, 8 - Sodium (Na-23) — Protons: 11 | Neutrons: 12 | Electrons per shell: 2, 8, 1 - Magnesium (Mg-24) — Protons: 12 | Neutrons: 12 | Electrons per shell: 2, 8, 2 - Aluminum (Al-27) — Protons: 13 | Neutrons: 14 | Electrons per shell: 2, 8, 3 - Silicon (Si-28) — Protons: 14 | Neutrons: 14 | Electrons per shell: 2, 8, 4 - Phosphorus (P-31) — Protons: 15 | Neutrons: 16 | Electrons per shell: 2, 8, 5 - Sulfur (S-32) — Protons: 16 | Neutrons: 16 | Electrons per shell: 2, 8, 6 - Chlorine (Cl-35) — Protons: 17 | Neutrons: 18 | Electrons per shell: 2, 8, 7 - Argon (Ar-40) — Protons: 18 | Neutrons: 22 | Electrons per shell: 2, 8, 8 - Potassium (K-39) — Protons: 19 | Neutrons: 20 | Electrons per shell: 2, 8, 8, 1 - Calcium (Ca-40) — Protons: 20 | Neutrons: 20 | Electrons per shell: 2, 8, 8, 2 Two conventions exist past calcium. School diagrams use 2, 8, 8 for the first 20 elements, as here; from scandium on, the third shell fills up toward its 18 — iron is 2, 8, 14, 2. Say which your course uses and the diagram follows it. #### Bohr model vs quantum mechanical model: what is the difference? The Bohr model puts each electron on a fixed circular orbit at a set distance from the nucleus; the quantum mechanical model replaces orbits with orbitals — regions where an electron is likely to be found — described by four quantum numbers. Bohr's numbered energy levels live on in the modern model as the principal quantum number n. - Where the electrons are — Bohr model (1913): On fixed circular orbits | Quantum mechanical model: In orbitals — probability clouds with no set path - Energy levels — Bohr model (1913): Quantized, numbered n = 1, 2, 3… | Quantum mechanical model: Quantized shells n, split into s, p, d and f subshells - Quantum numbers — Bohr model (1913): One (n) | Quantum mechanical model: Four (n, l, mₗ, mₛ) - Atoms it describes exactly — Bohr model (1913): Hydrogen and one-electron ions such as He⁺ | Quantum mechanical model: All atoms and molecules - What it explains — Bohr model (1913): The hydrogen line spectrum | Quantum mechanical model: Spectra, chemical bonding, magnetism and the layout of the periodic table - Best used for — Bohr model (1913): Counting protons, neutrons and electrons per shell; valence electrons | Quantum mechanical model: Electron configurations, orbital shapes, molecular orbital diagrams Use the Bohr model for what it gets right: electrons per shell and valence electrons. For orbital shapes, subshells or bonding, draw an electron configuration or a molecular orbital diagram instead. #### Where are Bohr model diagrams used? Bohr model diagrams are used mostly in middle-school and high-school science — labeling worksheets, element projects and exam revision — and in introductory physics to explain line spectra. What changes is the depth: electrons per shell in a first course, energy levels and emitted light in physics. - Middle-school science: Element worksheets and projects: count the protons, neutrons and electrons of one element and draw them in place. Usually the labeled atom, plus the same drawing blank. - High-school chemistry: GCSE, AP and IB chemistry: electron arrangements such as 2, 8, 1, valence electrons, and why elements in one group of the periodic table react alike. - Introductory physics: The energy levels of the hydrogen atom and the photon given out when an electron drops from n = 3 to n = 2 — the red 656 nm line of the Balmer series. - Ions and isotopes: Side-by-side diagrams of an atom and its ion (Na and Na⁺) or of two isotopes (carbon-12 and carbon-14), where only the electron or the neutron count changes. #### Common questions about Bohr model diagrams **What should a labeled Bohr model diagram include?** The nucleus with its number of protons and neutrons, each electron shell drawn as a circle, the electrons as dots or crosses on the shells, and the count on each shell. Many worksheets also ask for the element symbol, atomic number and mass number. That is the default — ask for fewer labels and only those are drawn. **What is a Bohr–Rutherford diagram?** A Bohr–Rutherford diagram is a Bohr model with the nucleus written out: the number of protons (p⁺) and neutrons (n⁰) inside it, and the electrons drawn on the shells around it. The name, used in many Canadian science courses, credits Rutherford's nucleus of 1911 and Bohr's shells of 1913. Ask for one by name and the nucleus is labeled in that form. **How many electrons go in each shell of a Bohr model?** 2 in the first shell, 8 in the second and, for the first 20 elements, 8 in the third before the fourth begins. The upper limit is 2n² — 2, 8, 18, 32 — but the 4s subshell fills before 3d, so potassium is 2, 8, 8, 1, not 2, 8, 9. **How do I find the number of neutrons for a Bohr model?** Subtract the atomic number from the mass number. Oxygen-16 has 8 protons and 16 − 8 = 8 neutrons; chlorine-35 has 17 protons and 18 neutrons. If no isotope is given, use the most common one — the table above lists it for the first 20 elements. **How do I draw a Bohr model of an ion?** Keep the nucleus the same and add or remove electrons on the outer shell. Na⁺ loses its single outer electron and is drawn 2, 8 with 11 protons; Cl⁻ gains one and is drawn 2, 8, 8 with 17 protons, usually in square brackets with the charge at the upper right. **What is the difference between a Bohr model and a Lewis dot diagram?** A Bohr model draws every shell and every electron; a Lewis dot diagram shows only the valence electrons, as dots around the element symbol. Sodium is 2, 8, 1 on a Bohr model and Na with a single dot as a Lewis symbol. For whole molecules, the Lewis structure generator on this site draws the bonds and lone pairs. **Why is the Bohr model wrong?** It is incomplete rather than wrong. Fixed circular orbits clash with the uncertainty principle and cannot predict the spectra of atoms with more than one electron; the quantum mechanical model replaced them with orbitals in the 1920s. It stays in textbooks because its shells and electron counts are still right and easy to draw. **Who created the Bohr model?** Niels Bohr, in 1913, building on Ernest Rutherford's nuclear atom of 1911. Bohr received the 1922 Nobel Prize in Physics for his work on the structure of atoms and the radiation they give out. **Can I make a simple Bohr model for younger students?** Yes — ask for a simple version and the diagram drops to the essentials: the nucleus with its counts and the electrons on each shell, five labels or fewer. #### Sources - The Bohr Model — Chemistry 2e, section 6.2 — OpenStax: https://openstax.org/books/chemistry-2e/pages/6-2-the-bohr-model - Development of Quantum Theory — Chemistry 2e, section 6.3 — OpenStax: https://openstax.org/books/chemistry-2e/pages/6-3-development-of-quantum-theory - Electronic Structure of Atoms (Electron Configurations) — Chemistry 2e, section 6.4 — OpenStax: https://openstax.org/books/chemistry-2e/pages/6-4-electronic-structure-of-atoms-electron-configurations --- ### Orbital Diagram Generator: Electron Configuration Diagrams URL: https://scientificfigure.com/tools/orbital-diagram-generator Description: Make an orbital diagram for any element or ion: boxes in Aufbau order, arrows set by Hund's rule and Pauli, unpaired electrons and the configuration. #### What is an orbital diagram? An orbital diagram (also called an orbital box diagram or orbital filling diagram) shows where an atom's electrons are: one box or line per orbital, grouped into subshells (1s, 2s, 2p, 3s …) in filling order, with each electron drawn as a half-arrow whose direction stands for its spin. It carries the same count as the electron configuration, 1s² 2s² 2p⁴ for oxygen, plus what the configuration leaves out: which orbitals hold a pair and which hold a single, unpaired electron. - Three rules place every arrow. Aufbau: fill the lowest-energy subshell first. Pauli: at most two electrons per orbital, with opposite spins. Hund: in a set of equal-energy orbitals, one electron goes into each before any pairs, all with the same spin. - 4s fills before 3d, and empties before it too. Potassium and calcium put their outer electrons in 4s and scandium starts 3d. When a transition metal forms a cation it loses its 4s electrons first: Fe is [Ar] 4s² 3d⁶, Fe²⁺ is [Ar] 3d⁶. - s, p, d and f sets have 1, 3, 5 and 7 orbitals. So an s subshell holds 2 electrons, p 6, d 10 and f 14, which is why the blocks of the periodic table are 2, 6, 10 and 14 elements wide. - Unpaired electrons make an atom paramagnetic. Count the single arrows: nitrogen has 3, oxygen 2, iron 4, chromium 6. An atom with every arrow paired, such as neon or zinc, is diamagnetic. - Chromium and copper break the simple order. Cr is [Ar] 4s¹ 3d⁵ and Cu is [Ar] 4s¹ 3d¹⁰: a half-filled or full 3d set is lower in energy than the configuration the filling order predicts. Molybdenum and silver, directly below them, do the same with 5s and 4d. #### Orbital filling and unpaired electrons, hydrogen to bromine Ground-state configurations as general chemistry textbooks give them, with the arrows in the last subshell to fill (□ is an empty box). The unpaired count is the number of single arrows in the whole diagram. - H — Electrons: 1 | Condensed configuration: 1s¹ | Last subshell's boxes: 1s: ↑ | Unpaired electrons: 1 - He — Electrons: 2 | Condensed configuration: 1s² | Last subshell's boxes: 1s: ↑↓ | Unpaired electrons: 0 - Li — Electrons: 3 | Condensed configuration: [He] 2s¹ | Last subshell's boxes: 2s: ↑ | Unpaired electrons: 1 - B — Electrons: 5 | Condensed configuration: [He] 2s² 2p¹ | Last subshell's boxes: 2p: ↑ □ □ | Unpaired electrons: 1 - C — Electrons: 6 | Condensed configuration: [He] 2s² 2p² | Last subshell's boxes: 2p: ↑ ↑ □ | Unpaired electrons: 2 - N — Electrons: 7 | Condensed configuration: [He] 2s² 2p³ | Last subshell's boxes: 2p: ↑ ↑ ↑ | Unpaired electrons: 3 - O — Electrons: 8 | Condensed configuration: [He] 2s² 2p⁴ | Last subshell's boxes: 2p: ↑↓ ↑ ↑ | Unpaired electrons: 2 - F — Electrons: 9 | Condensed configuration: [He] 2s² 2p⁵ | Last subshell's boxes: 2p: ↑↓ ↑↓ ↑ | Unpaired electrons: 1 - Ne — Electrons: 10 | Condensed configuration: [He] 2s² 2p⁶ | Last subshell's boxes: 2p: ↑↓ ↑↓ ↑↓ | Unpaired electrons: 0 - Na — Electrons: 11 | Condensed configuration: [Ne] 3s¹ | Last subshell's boxes: 3s: ↑ | Unpaired electrons: 1 - Mg — Electrons: 12 | Condensed configuration: [Ne] 3s² | Last subshell's boxes: 3s: ↑↓ | Unpaired electrons: 0 - Al — Electrons: 13 | Condensed configuration: [Ne] 3s² 3p¹ | Last subshell's boxes: 3p: ↑ □ □ | Unpaired electrons: 1 - Si — Electrons: 14 | Condensed configuration: [Ne] 3s² 3p² | Last subshell's boxes: 3p: ↑ ↑ □ | Unpaired electrons: 2 - P — Electrons: 15 | Condensed configuration: [Ne] 3s² 3p³ | Last subshell's boxes: 3p: ↑ ↑ ↑ | Unpaired electrons: 3 - S — Electrons: 16 | Condensed configuration: [Ne] 3s² 3p⁴ | Last subshell's boxes: 3p: ↑↓ ↑ ↑ | Unpaired electrons: 2 - Cl — Electrons: 17 | Condensed configuration: [Ne] 3s² 3p⁵ | Last subshell's boxes: 3p: ↑↓ ↑↓ ↑ | Unpaired electrons: 1 - Ar — Electrons: 18 | Condensed configuration: [Ne] 3s² 3p⁶ | Last subshell's boxes: 3p: ↑↓ ↑↓ ↑↓ | Unpaired electrons: 0 - K — Electrons: 19 | Condensed configuration: [Ar] 4s¹ | Last subshell's boxes: 4s: ↑ | Unpaired electrons: 1 - Ca — Electrons: 20 | Condensed configuration: [Ar] 4s² | Last subshell's boxes: 4s: ↑↓ | Unpaired electrons: 0 - Ti — Electrons: 22 | Condensed configuration: [Ar] 4s² 3d² | Last subshell's boxes: 3d: ↑ ↑ □ □ □ | Unpaired electrons: 2 - Cr — Electrons: 24 | Condensed configuration: [Ar] 4s¹ 3d⁵ (exception) | Last subshell's boxes: 4s: ↑, 3d: ↑ ↑ ↑ ↑ ↑ | Unpaired electrons: 6 - Mn — Electrons: 25 | Condensed configuration: [Ar] 4s² 3d⁵ | Last subshell's boxes: 3d: ↑ ↑ ↑ ↑ ↑ | Unpaired electrons: 5 - Fe — Electrons: 26 | Condensed configuration: [Ar] 4s² 3d⁶ | Last subshell's boxes: 3d: ↑↓ ↑ ↑ ↑ ↑ | Unpaired electrons: 4 - Co — Electrons: 27 | Condensed configuration: [Ar] 4s² 3d⁷ | Last subshell's boxes: 3d: ↑↓ ↑↓ ↑ ↑ ↑ | Unpaired electrons: 3 - Ni — Electrons: 28 | Condensed configuration: [Ar] 4s² 3d⁸ | Last subshell's boxes: 3d: ↑↓ ↑↓ ↑↓ ↑ ↑ | Unpaired electrons: 2 - Cu — Electrons: 29 | Condensed configuration: [Ar] 4s¹ 3d¹⁰ (exception) | Last subshell's boxes: 4s: ↑, 3d: five pairs | Unpaired electrons: 1 - Zn — Electrons: 30 | Condensed configuration: [Ar] 4s² 3d¹⁰ | Last subshell's boxes: 3d: five pairs | Unpaired electrons: 0 - Br — Electrons: 35 | Condensed configuration: [Ar] 4s² 3d¹⁰ 4p⁵ | Last subshell's boxes: 4p: ↑↓ ↑↓ ↑ | Unpaired electrons: 1 Scandium to zinc fill 3d after 4s, and only chromium and copper step out of line. Scandium ([Ar] 4s² 3d¹, 1 unpaired) and vanadium ([Ar] 4s² 3d³, 3 unpaired) follow the pattern. For a cation, take electrons from the highest n first: Cu⁺ and Zn²⁺ are both [Ar] 3d¹⁰. #### Orbital diagram vs electron configuration vs Bohr model All three describe the same electrons. The electron configuration writes them as a line of text (1s² 2s² 2p⁴), the orbital diagram draws each orbital with its arrows, and the Bohr model draws only shells as rings, with no subshells and no spin. Orbital notation is the box-and-arrow form, and most courses use it as another name for the orbital diagram. - What it shows — Orbital diagram: Every orbital as a box, each electron as an arrow | Electron configuration: Subshells with superscript electron counts | Bohr model: Shells as rings, electrons as dots - Oxygen — Orbital diagram: 1s ↑↓, 2s ↑↓, 2p ↑↓ ↑ ↑ | Electron configuration: 1s² 2s² 2p⁴, or [He] 2s² 2p⁴ | Bohr model: 2 dots on the first ring, 6 on the second - Spin — Orbital diagram: Shown by up and down arrows | Electron configuration: Not shown | Bohr model: Not shown - Unpaired electrons — Orbital diagram: Count the single arrows | Electron configuration: Worked out with Hund's rule | Bohr model: Cannot be read - Subshells (s, p, d) — Orbital diagram: Sets of 1, 3 and 5 boxes | Electron configuration: Written as 1s, 2p, 3d … | Bohr model: None, shells only - Against a molecular orbital diagram — Orbital diagram: One atom; an MO diagram puts two atoms' orbitals in its outer columns and combines them | Electron configuration: Molecules get MO configurations instead, written σ2s² σ*2s² … | Bohr model: No molecular counterpart Draw the orbital diagram when the question is about spin or magnetism. "How many unpaired electrons does iron have?" needs the five 3d boxes drawn out; "what is the electron configuration of iron?" needs only [Ar] 4s² 3d⁶. #### Orbital diagrams in chemistry courses and exams Orbital diagrams are drawn in high-school chemistry, AP and IB Chemistry and first-year general chemistry, wherever electron configurations, periodic trends and magnetism are taught. The elements change with the level: the first 20 in an introduction, transition metals and their ions later. - High-school chemistry: The first 20 elements, hydrogen to calcium, as a first look at subshells and the three filling rules. - AP and IB Chemistry: Transition metals, the chromium and copper exceptions, and ions such as Fe²⁺ and Fe³⁺, where 4s empties before 3d. - General chemistry problem sets: Questions on the number of unpaired electrons, or on which of two atoms is paramagnetic, answered by drawing the boxes. - Answer keys and lecture slides: One labeled diagram per element of a problem set, so students can check their arrow pattern box by box. #### Questions about orbital diagrams **How do you draw an orbital diagram?** Count the electrons, draw the subshells in filling order (1s, 2s, 2p, 3s, 3p, 4s, 3d …) as one box per orbital, and fill the boxes from the lowest up: two arrows per box pointing opposite ways, and one arrow in every box of a p or d set before any of them pairs. Stop when the arrows equal the atomic number, write the configuration underneath, and count the single arrows to get the unpaired electrons. **What is orbital notation?** Orbital notation is the electron configuration drawn as boxes or lines, one per orbital and labeled with its subshell, with each electron as an up or down arrow. Oxygen in orbital notation is 1s ↑↓, 2s ↑↓, 2p ↑↓ ↑ ↑. Textbooks that use the term keep "electron configuration" or "spdf notation" for the written form, 1s² 2s² 2p⁴. **What is the difference between an orbital diagram and an electron configuration?** The electron configuration says how many electrons each subshell holds; the orbital diagram also shows how they sit inside it. Both give 2p⁴ for oxygen, but only the diagram shows one 2p orbital paired and two holding single electrons, which is where oxygen's 2 unpaired electrons come from. **What is an Aufbau diagram?** An Aufbau diagram is the chart of the order in which subshells fill: the subshells written in rows by shell and crossed by diagonal arrows, read 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s and on. It follows the n + l rule. It is the tool for building an orbital diagram, not a diagram of any one atom. **Why does 4s fill before 3d?** Because for potassium and calcium 4s sits below 3d in energy: its n + l is 4, against 5 for 3d. Once 3d begins to fill, from scandium on, the 3d orbitals drop below 4s, which is why transition-metal cations lose their 4s electrons first: Fe²⁺ is [Ar] 3d⁶, not [Ar] 4s² 3d⁴. **Why are chromium and copper exceptions?** A half-filled or completely filled 3d set is more stable than the configuration the filling order predicts, so one 4s electron moves into 3d. Chromium is [Ar] 4s¹ 3d⁵ instead of 4s² 3d⁴, and copper is [Ar] 4s¹ 3d¹⁰ instead of 4s² 3d⁹. The 4s and 3d energies are so close there that the extra stability of the parallel 3d spins tips the balance. **How many unpaired electrons does iron have?** Four. Iron is [Ar] 4s² 3d⁶: 4s is paired, and of the six 3d electrons the first five go into separate boxes and the sixth pairs with one of them, leaving four single arrows. Fe³⁺, [Ar] 3d⁵, has five, one in every 3d box. **How do you draw an orbital diagram for an ion?** Start from the neutral atom's diagram and add or remove arrows for the charge. Anions take the extra electrons in the next open box: Cl⁻ is [Ne] 3s² 3p⁶. Cations lose them from the highest n first, so transition metals lose 4s before 3d: Fe³⁺ is [Ar] 3d⁵, five single arrows and no 4s box. **What does a valence electron orbital diagram show?** Only the outer shell: the s and p boxes of the highest n, with the core written as a noble-gas symbol. Sulfur's is [Ne] followed by 3s ↑↓ and 3p ↑↓ ↑ ↑, its 6 valence electrons and 2 unpaired ones. For transition metals the 3d boxes are usually drawn as well, since those electrons take part in bonding. **Why do the two arrows in one box point opposite ways?** The Pauli exclusion principle: two electrons in the same orbital must have opposite spins, +½ and −½, drawn as one up-arrow and one down-arrow. No orbital can take a third electron, so a box never holds more than two arrows. #### Sources - 5.17: Hund's Rule and Orbital Filling Diagrams, Introductory Chemistry (CK-12) — LibreTexts: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/05%3A_Electrons_in_Atoms/5.17%3A_Hund's_Rule_and_Orbital_Filling_Diagrams - Orbital Diagrams, General Chemistry — Chemistry Steps: https://general.chemistrysteps.com/orbital-diagrams/ --- ### Nitrogen Cycle Diagram — Labeled & Simple Versions, Free URL: https://scientificfigure.com/tools/nitrogen-cycle-diagram Description: Make a labeled nitrogen cycle diagram in seconds: fixation, ammonification, nitrification and denitrification arrows, or a simple version for a first lesson. #### What is a nitrogen cycle diagram? A nitrogen cycle diagram shows how nitrogen moves between the air, the soil and living things: bacteria fix nitrogen gas into ammonium, nitrifying bacteria turn it into nitrate, plants absorb it, and denitrifying bacteria return it to the air. Each arrow names its process. - Nitrogen gas makes up about 78 percent of the atmosphere, but plants cannot use it. The two atoms in N₂ are held by a triple bond, so the gas must first be fixed into ammonia or ammonium before plants and phytoplankton can take it up. - Nitrogen fixation is done mostly by bacteria. Rhizobium lives in the root nodules of legumes such as peas, beans and clover; cyanobacteria and free-living soil bacteria such as Azotobacter fix nitrogen too, and lightning fixes a little with no organism involved. - Nitrification takes two groups of microbes. Ammonia-oxidizers such as Nitrosomonas turn ammonium into nitrite; a separate group, nitrite-oxidizers such as Nitrobacter, turn nitrite into nitrate. Both steps need oxygen. - Denitrification closes the loop. In waterlogged soil, sediments and other low-oxygen places, bacteria such as Pseudomonas reduce nitrate back to nitrogen gas, releasing some nitrous oxide (N₂O), a greenhouse gas, along the way. - Human activity has doubled global nitrogen fixation. Fertilizer made by the Haber-Bosch process and the burning of fossil fuels add fixed nitrogen on the scale of all natural sources; runoff of the excess causes eutrophication in lakes, rivers and coastal seas. #### Processes of the nitrogen cycle and what each one does The processes a labeled nitrogen cycle diagram is normally expected to name on its arrows, what each one does, and which organisms carry it out. This is the default label set unless you ask for a shorter one. - Nitrogen fixation — What happens: Nitrogen gas (N₂) is converted into ammonia (NH₃) or ammonium (NH₄⁺) | Carried out by: Rhizobium in legume root nodules, cyanobacteria, free-living soil bacteria such as Azotobacter - Lightning fixation — What happens: The energy of a lightning strike fixes a small amount of atmospheric nitrogen | Carried out by: No organism — an abiotic process - Industrial fixation — What happens: Nitrogen and hydrogen react to make ammonia for fertilizer (the Haber-Bosch process) | Carried out by: Fertilizer plants - Assimilation — What happens: Plants take up ammonium and nitrate through their roots and build them into proteins and nucleic acids | Carried out by: Plants, then the animals that eat them - Ammonification — What happens: Decomposers break down dead organisms and animal waste, releasing ammonium | Carried out by: Bacteria and fungi - Nitrification, step 1 — What happens: Ammonium is oxidized to nitrite (NO₂⁻) | Carried out by: Ammonia-oxidizing bacteria such as Nitrosomonas, and ammonia-oxidizing archaea - Nitrification, step 2 — What happens: Nitrite is oxidized to nitrate (NO₃⁻) | Carried out by: Nitrite-oxidizing bacteria such as Nitrobacter - Denitrification — What happens: Nitrate is reduced step by step to nitrogen gas, which returns to the atmosphere | Carried out by: Bacteria such as Pseudomonas and Clostridium, in low-oxygen soil and water - Anammox — What happens: Ammonium and nitrite react to form nitrogen gas without oxygen | Carried out by: Planctomycetes bacteria in low-oxygen water and sediments Courses differ in how many of these they expect. Introductory worksheets often stop at fixation, nitrification, assimilation and denitrification; ecology and microbiology courses add ammonification, the two steps of nitrification, anammox and industrial fixation. Name the labels you need and only those are drawn. #### Nitrification vs denitrification: what is the difference? Nitrification turns ammonium into nitrate, keeping nitrogen in the soil in a form plants can absorb; denitrification turns nitrate into nitrogen gas, removing it from the soil and returning it to the air. Nitrification needs oxygen; denitrification happens where oxygen is scarce. - What it converts — Nitrification: Ammonium (NH₄⁺) → nitrite (NO₂⁻) → nitrate (NO₃⁻) | Denitrification: Nitrate (NO₃⁻) → nitrite and gaseous oxides → nitrogen gas (N₂) - Oxygen — Nitrification: Needs oxygen (aerobic) | Denitrification: Happens without oxygen (anaerobic) - Where it happens — Nitrification: Well-aerated soil and water | Denitrification: Waterlogged soil, sediments, low-oxygen zones of lakes and oceans - Microbes — Nitrification: Nitrosomonas, then Nitrobacter | Denitrification: Pseudomonas, Paracoccus, Bacillus and others - Energy for the microbes — Nitrification: Oxidizing ammonium or nitrite — very little, so they grow slowly | Denitrification: Breaking down organic carbon, with nitrate in place of oxygen - Effect on the soil — Nitrification: Keeps nitrogen in the soil, as nitrate that plants absorb | Denitrification: Removes nitrogen from the soil - Side effect to watch — Nitrification: Nitrate washing into streams and drinking water | Denitrification: Nitrous oxide (N₂O), a greenhouse gas Draw nitrification as two arrows, ammonium to nitrite and nitrite to nitrate, and denitrification as one arrow from nitrate back to the atmosphere. A diagram that labels the arrow from nitrate to the air as nitrification, or joins ammonium straight to nitrate with no nitrite step, is the error to check for first. #### Where are nitrogen cycle diagrams used? Nitrogen cycle diagrams are used mostly in biology, ecology and environmental science teaching — labeling worksheets, exam revision and lesson slides — and in farming, soil science and water-quality work. What changes is the depth: bacteria, plants and decomposers for a first course, every chemical form and the microbe behind each step for a university one. - School biology and ecology: Labeling worksheets and revision sheets from middle school life science through GCSE, A-level, AP Environmental Science and IB. Usually the labeled cycle, plus the same drawing blank for students to fill in. - University ecology and microbiology: Lectures on biogeochemical cycles and soil microbes: the nitrogenase enzyme, ammonia-oxidizing archaea, anammox, and why nitrogen so often limits plant growth. - Farming and soil science: Course slides and extension sheets on legumes in crop rotation, fertilizer timing and nitrate loss — where the cycle explains why a crop of peas or clover leaves nitrogen in the soil. - Water quality and environment: Panels on fertilizer runoff, eutrophication and wastewater treatment, where nitrifying and denitrifying bacteria are put to work removing ammonium and nitrate. #### Common questions about nitrogen cycle diagrams **What should a labeled nitrogen cycle diagram include?** The standard set is nitrogen gas in the atmosphere, nitrogen-fixing bacteria in root nodules and in the soil, ammonium, nitrite and nitrate, plants, animals and decomposers, joined by arrows labeled nitrogen fixation, assimilation, ammonification, nitrification and denitrification. That is the default — ask for fewer labels and only those are drawn. **How does the nitrogen cycle work in an aquarium?** Fish waste and leftover food release ammonia, nitrifying bacteria in the filter and gravel turn it into nitrite and then nitrate, and water changes and plants remove the nitrate. Ammonia and nitrite harm fish even at low levels, so a new tank is “cycled” for several weeks until the bacteria can keep up. In a tank the nitrogen comes in with the food rather than from the air. **What are the steps of the nitrogen cycle in order?** Nitrogen fixation, nitrification, assimilation, ammonification and denitrification. Bacteria fix N₂ into ammonium; nitrifying bacteria turn ammonium into nitrite and then nitrate; plants absorb nitrate and ammonium and animals eat the plants; decomposers return the nitrogen in waste and dead tissue as ammonium; denitrifying bacteria turn nitrate back into N₂. Nitrogen can pass between the soil and living things many times before it returns to the air. **Why can't plants use nitrogen from the air?** Because the two atoms in N₂ are held by a triple bond that plants have no enzyme to break. Only certain bacteria and archaea carry nitrogenase, the enzyme that reduces N₂ to ammonia, and the reaction costs at least 16 ATP for every molecule of N₂ fixed. **What do the bacteria in legume root nodules do?** They fix nitrogen for the plant. Rhizobium bacteria are drawn to the roots of legumes such as peas, beans, soybeans and clover, enter them and form nodules, where they turn nitrogen gas into a form the plant can use. That is why gardeners and farmers grow peas and clover partly to add nitrogen to the soil. **Is nitrogen fixation the same as nitrification?** No — nitrogen fixation turns nitrogen gas into ammonia or ammonium; nitrification turns ammonium into nitrite and then nitrate. Fixation brings nitrogen into the living world from the air; nitrification changes its form once it is already in the soil. Different microbes do each: Rhizobium and Azotobacter fix, Nitrosomonas and Nitrobacter nitrify. **What is ammonification?** Ammonification is the release of ammonium by decomposers. When an organism dies or excretes waste, the nitrogen in its proteins and nucleic acids is organic; bacteria and fungi break it down and release it as ammonia or ammonium, which plants can take up or nitrifying bacteria can oxidize. **How do humans affect the nitrogen cycle?** Mainly through fertilizer and the burning of fossil fuels, which together have doubled the amount of nitrogen fixed each year. Unused fertilizer nitrate washes into rivers and lakes and causes eutrophication — overgrowth that uses up the dissolved oxygen — while nitrogen oxides from combustion add to acid rain and nitrous oxide to climate change. **Can I make a simple nitrogen cycle drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: nitrogen in the air, bacteria fixing it in the soil, plants and animals using it, and decomposers returning it. Five labels or fewer usually covers a middle-school class. **How does the tool keep the nitrogen cycle's arrows pointing the right way?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — each stage in its true order around a closed loop, joined by arrows that name the process — with each label spelled exactly. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a nitrogen cycle diagram from here in an ecology lesson or a report?** Yes — the nitrogen cycle diagrams you generate are yours to use in ecology and environmental science worksheets, slides, reports and theses. Export goes up to 4K depending on the model. **Can I rename the processes or translate the nitrogen cycle labels afterwards?** Yes. The canvas recognizes each label, so you can change 'ammonification' to 'mineralization', write nitrate as NO₃⁻, translate the set or recolor the arrows without regenerating the figure. #### Sources - Biogeochemical Cycles — Biology 2e, section 46.3 — OpenStax: https://openstax.org/books/biology-2e/pages/46-3-biogeochemical-cycles - The Nitrogen Cycle: Processes, Players, and Human Impact — Nature Education (Scitable): https://www.nature.com/scitable/knowledge/library/the-nitrogen-cycle-processes-players-and-human-15644632/ --- ### Neuron Diagram — Labeled Parts & Blank Worksheet, Free URL: https://scientificfigure.com/tools/neuron-diagram Description: Make a labeled neuron diagram: dendrites, cell body, axon hillock, myelin sheath, nodes of Ranvier and axon terminals. Free blank worksheet and answer key. #### What is a neuron diagram? A neuron diagram shows the parts of a nerve cell in the order a signal passes through them: the dendrites receive it, the cell body integrates it, and the axon carries it from the axon hillock, past the myelin sheath and nodes of Ranvier, to the axon terminals. Most textbooks draw a multipolar motor neuron, labeled part by part with the impulse running left to right. - A signal runs one way through a neuron: dendrites → cell body → axon → axon terminals. The dendrites and cell body collect inputs from other cells, and only the axon carries the impulse on to the next neuron, muscle fiber or gland. - The action potential starts at the axon hillock. This trigger zone, where the cell body tapers into the axon, fires once the summed inputs lift the membrane from its resting −70 mV to a threshold of about −55 mV. - Myelin raises conduction speed from about 0.5–2 m/s to as much as 120 m/s. The impulse jumps from one node of Ranvier to the next — saltatory conduction — because the voltage-gated Na⁺ channels are concentrated in those bare gaps, about 1 mm apart. - Schwann cells make the myelin in the peripheral nervous system; oligodendrocytes make it in the brain and spinal cord. Each Schwann cell wraps one segment of a single axon, while one oligodendrocyte can myelinate segments of many axons. - Neurons are sorted three ways by job: sensory neurons, interneurons and motor neurons. Sensory neurons bring signals in from receptors, interneurons connect neurons inside the brain and spinal cord, and motor neurons carry commands out to muscles and glands; by shape, neurons are multipolar, bipolar or unipolar. #### Parts of a neuron and what each one does The parts a labeled neuron diagram is normally expected to show, what each one does, and where it sits along the cell, in the order a signal passes through them. This is the default label set unless you ask for a shorter one. - Dendrites — What it does: Receive signals from other neurons and pass them toward the cell body | Where it sits: Branching out from the cell body; the start of the signal path - Cell body (soma) — What it does: Integrates the incoming signals and keeps the cell alive, making its proteins | Where it sits: Between the dendrites and the axon - Nucleus — What it does: Holds the cell's DNA and directs protein synthesis | Where it sits: Inside the cell body - Axon hillock — What it does: Sums the inputs and starts the action potential when the membrane reaches threshold | Where it sits: Where the cell body tapers into the axon - Axon — What it does: Carries the action potential away from the cell body — about 1 m long in the motor neurons that reach the foot | Where it sits: From the axon hillock to the axon terminals - Myelin sheath — What it does: Insulates the axon so the impulse jumps between gaps and travels much faster | Where it sits: Wrapped around the axon in segments - Schwann cell — What it does: Forms one myelin segment around a peripheral axon and helps a cut peripheral axon regrow | Where it sits: Along the axon, with its nucleus on the outside of the sheath - Node of Ranvier — What it does: A bare gap packed with voltage-gated Na⁺ channels, where the impulse is regenerated | Where it sits: Between neighboring myelin segments, about 1 mm apart - Axon terminals — What it does: Release neurotransmitter from synaptic vesicles to pass the signal on | Where it sits: The branched far end of the axon, each ending in a synaptic end bulb - Synapse — What it does: The junction where the signal crosses to the next cell, over a cleft about 20–40 nm wide | Where it sits: Between an axon terminal and a dendrite, muscle fiber or gland cell Courses differ in how many parts they expect. Introductory worksheets often stop at the dendrites, cell body, nucleus, axon and axon terminals; GCSE, A-level and anatomy-and-physiology courses add the myelin sheath, nodes of Ranvier and Schwann cells, and university courses the axon hillock, Nissl bodies and synaptic end bulbs. Name the labels you need and only those are drawn. #### Sensory vs motor neuron: what is the difference? Sensory neurons carry signals from receptors into the brain and spinal cord; motor neurons carry commands out of them to muscles and glands. They also look different: a sensory neuron is usually unipolar, with its cell body to one side of the axon, while a motor neuron is multipolar, with its dendrites around the cell body at the start of the axon. - Also called — Sensory neuron: Afferent neuron | Motor neuron: Efferent neuron - Direction of the signal — Sensory neuron: From a receptor toward the brain and spinal cord | Motor neuron: From the brain and spinal cord to a muscle or gland - Shape — Sensory neuron: Usually unipolar (pseudounipolar): one process that splits into a peripheral and a central branch | Motor neuron: Multipolar: many dendrites and one long axon - Cell body — Sensory neuron: To the side of the axon, in a ganglion such as the dorsal root ganglion | Motor neuron: At the start of the axon, in the spinal cord's ventral horn or the brainstem - Dendrites — Sensory neuron: At the receptor end, far from the cell body | Motor neuron: Branching straight from the cell body - Ends on — Sensory neuron: Interneurons or motor neurons in the brain and spinal cord | Motor neuron: Muscle fibers at the neuromuscular junction, or gland cells Check where the cell body sits. A sensory neuron's cell body hangs to one side of the axon on a short stalk, while a motor neuron's sits at the start of the axon among its dendrites; a diagram that draws both the same way, or points the impulse arrow back toward the receptor, is the error to look for first. #### Where are neuron diagrams used? Neuron diagrams are used mostly in biology and anatomy-and-physiology teaching — labeling worksheets, quizzes and lecture slides — and in medicine and neuroscience, where they show which part of the cell a disease or a drug acts on. What changes is the depth: five parts for a first course, the trigger zone and myelin for A&P, the ion channels at each node for medicine. - School biology: Labeling worksheets and revision sheets for GCSE, A-level, AP Biology and IB, where the neuron opens the topic of nervous coordination and the reflex arc. Usually the labeled neuron, plus the same drawing blank for students to fill in. - Anatomy & physiology and nursing: A&P lab sheets and nursing lectures that pair the parts of a neuron with nervous tissue, the glial cells and the reflex arc — the figure students label before they learn how the impulse travels. - Medicine: Neurology and pharmacology slides that mark where a condition strikes: lost myelin in multiple sclerosis, the peripheral nerves in Guillain–Barré syndrome, the Na⁺ channels that local anesthetics block. - Research and textbook figures: Schematic panels for neuroscience papers, posters and textbook chapters — a neuron with the recorded region, the labeled cell type or the injected site highlighted. #### Common questions about neuron diagrams **What are the parts of a neuron in order?** In the order a signal travels: dendrites, the cell body (soma) with its nucleus, the axon hillock, the axon — wrapped in a myelin sheath broken by nodes of Ranvier — and the axon terminals. The terminals end at synapses with the next neuron, a muscle fiber or a gland cell. **What should a labeled neuron diagram include?** The standard set is the dendrites, cell body (soma), nucleus, axon hillock, axon, myelin sheath, Schwann cells, nodes of Ranvier and axon terminals, often with an arrow showing the direction of the impulse. That is the default — ask for fewer labels and only those are drawn. **Can I get a blank neuron diagram to label?** Yes — view the blank version on this page free, or ask for one and every label is replaced by an empty answer line. The labeled version is the matching answer key, so the two print as a pair and work as a neuron labeling quiz. **How do you draw a neuron?** Draw a round cell body with its nucleus, add short branching dendrites around it, then run one long axon out from a cone-shaped axon hillock and end it in a few branched axon terminals. Wrap the axon in a row of sausage-shaped myelin segments with small gaps between them for the nodes of Ranvier, then add the labels — or describe the drawing here and it is made for you. **What does the myelin sheath do?** It insulates the axon, so the impulse jumps from one node of Ranvier to the next instead of creeping along the whole membrane — saltatory conduction. That raises the speed from about 0.5–2 m/s in unmyelinated axons to as much as 120 m/s. When myelin is lost, as in multiple sclerosis, the signal slows or fails. **What are the 3 types of neurons?** Sensory neurons, interneurons and motor neurons. Sensory neurons carry signals from receptors into the brain and spinal cord, interneurons connect neurons inside them, and motor neurons carry commands out to muscles and glands. By shape, neurons are also grouped as multipolar, bipolar or unipolar. **What does the axon hillock do?** It adds up the excitatory and inhibitory inputs reaching the cell body and fires an action potential when the membrane reaches threshold, about −55 mV. Together with the initial segment just beyond it, it forms the trigger zone, where voltage-gated Na⁺ channels are dense enough to start the impulse. **What are the nodes of Ranvier?** Short gaps in the myelin sheath, about 1 mm apart, where the axon membrane is bare. Voltage-gated Na⁺ channels cluster there, so the action potential is regenerated at each node and skips the insulated stretch between them. **What is the difference between a dendrite and an axon?** Dendrites carry signals toward the cell body; the axon carries them away from it. A neuron usually has many short, branching dendrites but only one axon, which can be about a meter long and ends in terminals that release neurotransmitter. #### Sources - Nervous Tissue — Anatomy and Physiology 2e, section 12.2 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/12-2-nervous-tissue - Neurons and Glial Cells — Biology 2e, section 35.1 — OpenStax: https://openstax.org/books/biology-2e/pages/35-1-neurons-and-glial-cells --- ### Nephron Diagram — Labeled & Blank, Free Maker URL: https://scientificfigure.com/tools/nephron-diagram Description: Make a labeled nephron diagram in seconds: glomerulus, Bowman's capsule, PCT, loop of Henle, DCT and collecting duct. Free blank worksheet and answer key. #### What is a nephron diagram? A nephron diagram shows the kidney's filtering unit: the glomerulus filters blood into Bowman's capsule, and the filtrate flows through the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule into a collecting duct. Each part is labeled with its job. - Each kidney holds over a million nephrons. About 85 percent are cortical nephrons, in the renal cortex with short loops of Henle; about 15 percent are juxtamedullary nephrons, next to the medulla, whose long loops reach deep into it. - A nephron does three jobs: filtration, reabsorption and secretion. The glomerulus filters the blood, the tubules take back what the body needs, and wastes such as urea, creatinine and ammonia, excess K⁺ and some drugs are secreted into the filtrate. - Up to 180 liters of filtrate a day become 1 to 2 liters of urine. Both kidneys together filter about 125 mL of plasma a minute in men and 105 mL in women, and about 99 percent of that filtrate is returned to the blood. - The proximal convoluted tubule does most of the reclaiming. It reabsorbs about 65 percent of the sodium and 67 percent of the water in the filtrate and almost all of the glucose and amino acids, across a brush border of microvilli. - The loop of Henle lets the kidney concentrate urine. Water leaves its descending limb and salt is pumped out of its ascending limb, building a salt gradient in the medulla that the collecting duct uses, under ADH, to take back water. #### Parts of the nephron and what each one does The parts a labeled nephron diagram is normally expected to show, what each one does, and where it sits in the kidney. This is the default label set unless you ask for a shorter one. - Afferent arteriole — What it does: Brings blood into the glomerulus | Where it sits: Renal cortex, entering the renal corpuscle - Glomerulus — What it does: A tuft of high-pressure capillaries that filters water, salts, glucose and urea out of the blood, holding back cells and large proteins | Where it sits: Renal cortex, inside Bowman's capsule - Efferent arteriole — What it does: Carries blood out of the glomerulus to the peritubular capillaries | Where it sits: Renal cortex, leaving the renal corpuscle - Bowman's capsule — What it does: Cup that catches the filtrate and funnels it into the tubule | Where it sits: Renal cortex, around the glomerulus - Proximal convoluted tubule (PCT) — What it does: Reabsorbs most of the water and sodium and almost all of the glucose and amino acids | Where it sits: Renal cortex - Descending limb of the loop of Henle — What it does: Lets water leave the filtrate by osmosis | Where it sits: Dips into the renal medulla - Ascending limb of the loop of Henle — What it does: Moves Na⁺ and Cl⁻ out but keeps water in, diluting the filtrate | Where it sits: Rises from the medulla back to the cortex - Distal convoluted tubule (DCT) — What it does: Secretes K⁺ and H⁺ and reabsorbs Na⁺, Cl⁻ and HCO₃⁻, fine-tuning salt balance and pH | Where it sits: Renal cortex - Collecting duct — What it does: Gathers filtrate from several nephrons and reabsorbs water when ADH is present | Where it sits: From the cortex down through the medulla - Peritubular capillaries and vasa recta — What it does: Carry the reabsorbed water and solutes back into the blood | Where it sits: Around the tubules; the vasa recta beside the loop of Henle Courses differ in how many parts they expect. Introductory worksheets often stop at the glomerulus, Bowman's capsule, the tubule, the loop of Henle and the collecting duct; A-level and university courses split the tubule into PCT and DCT and add the afferent and efferent arterioles, the vasa recta and the juxtaglomerular apparatus. Name the labels you need and only those are drawn. #### Cortical vs juxtamedullary nephron: what is the difference? Cortical nephrons lie in the renal cortex and have short loops of Henle that barely reach the medulla; juxtamedullary nephrons lie next to the medulla and have long loops that run deep into it. About 85 percent of nephrons are cortical; the 15 percent that are juxtamedullary build the salt gradient that concentrates urine. - Share of nephrons — Cortical nephron: About 85 percent | Juxtamedullary nephron: About 15 percent - Renal corpuscle — Cortical nephron: In the renal cortex, away from the medulla | Juxtamedullary nephron: In the cortex, next to the medulla - Loop of Henle — Cortical nephron: Short, entering the medulla little if at all | Juxtamedullary nephron: Long, some reaching deep into the medulla - Capillaries around the tubule — Cortical nephron: Peritubular capillaries around the PCT and DCT | Juxtamedullary nephron: Peritubular capillaries plus the vasa recta along the loop - Main role — Cortical nephron: Everyday filtration and reabsorption | Juxtamedullary nephron: Building the salt gradient that concentrates urine Draw the juxtamedullary loop hairpinning deep into the medulla with the vasa recta beside it, and the cortical loop staying short near the cortex. A diagram with both loops the same length, or with the collecting duct drawn as one nephron's own tubule rather than shared by several, is the error to check for first. #### Where are nephron diagrams used? Nephron diagrams are used mostly in biology and physiology teaching — labeling worksheets, exam revision and lecture slides — and in medical, nursing and pharmacology courses that show where hormones and drugs act along the tubule. What changes is the depth: five parts for a first course, every segment with what it moves for a medical one. - School biology: Labeling worksheets and revision sheets for GCSE, A-level, AP Biology and IB, where the nephron is the core of excretion and osmoregulation. Usually the labeled nephron, plus the same drawing blank for students to fill in. - Medicine and nursing: Physiology and pharmacology slides that put each control on its segment: ADH and aldosterone on the collecting duct, loop diuretics on the ascending limb of the loop of Henle. - Exam revision: One-page summaries that match each part to its job — which is how exam questions ask about them: name the structure at X, explain why glucose appears in the urine in untreated diabetes. - Research and patient education: Schematic panels for kidney research and patient leaflets on kidney disease, with the affected part of the nephron highlighted. #### Common questions about nephron diagrams **What should a labeled nephron diagram include?** The standard set is the afferent arteriole, glomerulus, efferent arteriole, Bowman's capsule, proximal convoluted tubule, descending and ascending limbs of the loop of Henle, distal convoluted tubule and collecting duct, often with the peritubular capillaries and the renal cortex and medulla marked. That is the default — ask for fewer labels and only those are drawn. **Can I get a blank nephron diagram for students to label?** Yes — the blank nephron on this page is free to view, and you can ask for your own. The arterioles, glomerulus, Bowman's capsule, tubule segments and collecting duct become empty answer lines; the labeled nephron above it is the matching answer key. **What are the parts of a nephron in order?** The glomerulus and Bowman's capsule (together the renal corpuscle), then the proximal convoluted tubule, the descending limb of the loop of Henle, the ascending limb and the distal convoluted tubule, which empties into a collecting duct. The collecting duct serves several nephrons and is continuous with the nephron but not strictly part of it. **What is the function of the nephron?** It filters the blood and turns the filtrate into urine, in three steps: glomerular filtration, tubular reabsorption and tubular secretion. Along the way it keeps the blood's water, salt and pH in balance, and the nephron's juxtaglomerular cells help control blood pressure by releasing renin. **What does the loop of Henle do?** It builds a salt gradient in the renal medulla that lets the kidney make concentrated urine. Water leaves the descending limb by osmosis; salt is moved out of the ascending limb, which lets no water follow. Because the two limbs work in opposite ways, the loop acts as a countercurrent multiplier. **Where is most water reabsorbed in the nephron?** In the proximal convoluted tubule, which takes back about two-thirds of the water in the filtrate. The descending limb of the loop of Henle reclaims about 15 percent more and the distal convoluted tubule about 8 percent; the collecting duct takes back a variable amount set by ADH — almost all that reaches it when you are dehydrated, almost none when you are over-hydrated. **What does ADH do in the nephron?** ADH (antidiuretic hormone) makes the collecting duct permeable to water. It signals the duct's cells to insert aquaporin water channels into their membranes, so water leaves the filtrate and returns to the blood and the urine is more concentrated. Without ADH the channels are not inserted and dilute urine is excreted. **Why is there no glucose in normal urine?** Because the proximal convoluted tubule reabsorbs almost 100 percent of the filtered glucose. Glucose passes freely into the filtrate and is carried back into the blood together with sodium. It appears in the urine only when blood glucose is high enough to saturate those carriers — usually a sign of type 1 or type 2 diabetes. **Can I make a simple nephron drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: the glomerulus, Bowman's capsule, the tubule, the loop of Henle and the collecting duct. Five labels or fewer usually covers a first biology class. **How does the tool keep the nephron's segments in the right order?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — every part of the nephron in its true position, order and relative proportion — with each label spelled exactly and set on a straight leader line. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a nephron diagram from here in a physiology class or a paper?** Yes — the nephron diagrams you generate are yours to use in physiology worksheets, nursing and medical revision notes, slides and theses. Export goes up to 4K depending on the model. **Can I switch to the newer anatomical terms or translate the labels afterwards?** Yes. The canvas recognizes each label, so you can change 'Bowman's capsule' to 'glomerular capsule' or 'loop of Henle' to 'nephron loop', translate the set, or recolor the vessels without regenerating the figure. #### Sources - The Kidneys and Osmoregulatory Organs — Biology 2e, section 41.2 — OpenStax: https://openstax.org/books/biology-2e/pages/41-2-the-kidneys-and-osmoregulatory-organs - Microscopic Anatomy of the Kidney — Anatomy and Physiology 2e, section 25.4 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/25-4-microscopic-anatomy-of-the-kidney - Tubular Reabsorption — Anatomy and Physiology 2e, section 25.6 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/25-6-tubular-reabsorption --- ### Synapse Diagram — Labeled & Blank, Free Maker URL: https://scientificfigure.com/tools/synapse-diagram Description: Make a labeled synapse diagram in seconds: vesicles, neurotransmitter, Ca²⁺ channels, cleft and receptors. Plus the neuromuscular junction and blank worksheet. #### What is a synapse diagram? A synapse diagram shows the junction where one neuron passes its signal to the next cell: an action potential opens Ca²⁺ channels in the axon terminal, synaptic vesicles release neurotransmitter into the synaptic cleft, and the neurotransmitter binds to receptors on the postsynaptic membrane. Each part is labeled with its job. - The synaptic cleft is only about 20–40 nm wide. The neurotransmitter crosses it by diffusion, and release plus diffusion add a synaptic delay of about 1 ms between the action potential arriving and the postsynaptic channels opening. - Release is triggered by Ca²⁺. When the action potential depolarizes the axon terminal, voltage-gated Ca²⁺ channels open, Ca²⁺ flows in, and synaptic vesicles fuse with the presynaptic membrane and empty by exocytosis. - A chemical synapse works in one direction only. Vesicles sit in the presynaptic terminal and receptors on the postsynaptic membrane, so the signal cannot run backwards — unlike some electrical synapses, which pass current both ways through gap junctions. - The response depends on the receptor. Ionotropic receptors are ligand-gated ion channels that open within milliseconds; metabotropic receptors act through G proteins and second messengers, more slowly and for longer. - The signal is ended in three ways: enzymes, reuptake and diffusion. Acetylcholinesterase splits acetylcholine in the cleft; serotonin, dopamine and norepinephrine are pumped back into the terminal by reuptake transporters, the target of SSRIs. #### Parts of a synapse and what each one does The parts a labeled chemical synapse diagram is normally expected to show, what each one does, and where it sits. This is the default label set unless you ask for a shorter one. - Axon terminal (presynaptic terminal) — What it does: Turns the arriving action potential into a chemical signal | Where it sits: End of the presynaptic neuron's axon - Synaptic vesicles — What it does: Store neurotransmitter and release it by exocytosis | Where it sits: Inside the axon terminal, clustered at the active zone - Neurotransmitter — What it does: The chemical messenger — acetylcholine, glutamate, GABA, dopamine and others — that carries the signal across the cleft | Where it sits: Stored in vesicles, released into the cleft - Voltage-gated Ca²⁺ channels — What it does: Open when the terminal depolarizes and let Ca²⁺ in, which triggers vesicle fusion | Where it sits: Presynaptic membrane, at the active zone - Mitochondria — What it does: Supply the ATP for refilling vesicles and pumping ions | Where it sits: Inside the axon terminal - Synaptic cleft — What it does: The gap, about 20–40 nm wide, that the neurotransmitter diffuses across | Where it sits: Between the presynaptic and postsynaptic membranes - Receptors (ligand-gated ion channels) — What it does: Bind the neurotransmitter and open, letting ions through to change the membrane potential | Where it sits: Postsynaptic membrane - Postsynaptic membrane — What it does: Carries the receptors; its change in potential is the EPSP or IPSP | Where it sits: Dendrite, cell body or muscle fiber of the receiving cell - Reuptake transporter — What it does: Carries neurotransmitter back into the terminal, ending the signal and recycling the transmitter | Where it sits: Presynaptic membrane and nearby glial cells - Enzymes in the cleft (such as acetylcholinesterase) — What it does: Break the neurotransmitter down | Where it sits: Synaptic cleft Courses differ in how much of the synapse they expect. Introductory worksheets usually stop at the axon terminal, vesicles, neurotransmitter, synaptic cleft and receptors; A-level, AP and university courses add the Ca²⁺ channels, reuptake or enzyme breakdown, mitochondria and the split between ionotropic and metabotropic receptors. Name the labels you need and only those are drawn. #### Chemical vs electrical synapse: what is the difference? A chemical synapse passes the signal as a neurotransmitter released across a cleft of about 20–40 nm; an electrical synapse passes ions straight from cell to cell through gap junctions. Chemical synapses are by far the more common; electrical synapses are faster and keep groups of neurons firing in step. - Gap between the cells — Chemical synapse: Synaptic cleft, about 20–40 nm | Electrical synapse: Gap junction, about 3.5 nm, the membranes joined by channel proteins - How the signal crosses — Chemical synapse: Neurotransmitter released from vesicles binds receptors | Electrical synapse: Ions flow directly through the gap-junction channels - Speed — Chemical synapse: Synaptic delay of about 1 ms | Electrical synapse: Virtually instantaneous - Direction — Chemical synapse: One-way, presynaptic to postsynaptic | Electrical synapse: Often two-way - Effect on the signal — Chemical synapse: Can excite or inhibit, amplify, and be changed by drugs | Electrical synapse: Passes the change in voltage on with little alteration - Plasticity — Chemical synapse: Strengthened or weakened by use — long-term potentiation and depression, the basis of learning | Electrical synapse: Little; mainly synchronizes the activity of neighboring cells Draw the chemical synapse with a visible cleft, vesicles on the presynaptic side only and receptors on the postsynaptic side only, and the electrical synapse with the two membranes almost touching, joined by gap-junction channels. Receptors on both sides of a chemical synapse, or vesicles in an electrical one, are the errors to check for first. #### Where are synapse diagrams used? Synapse diagrams are used mostly in biology and physiology teaching — labeling worksheets, exam revision and lecture slides — and in medicine and pharmacology, where many drugs that act on the nervous system are explained at the synapse. What changes is the depth: five labels for a first course, every channel and transporter for a medical one. - School biology: Labeling worksheets and revision sheets for GCSE, A-level, AP Biology and IB, where the synapse comes with nervous coordination and the effect of drugs. Usually the labeled synapse, plus the same drawing blank for students to fill in. - Anatomy, physiology and nursing: A&P and nursing slides on how a nerve signal passes from cell to cell and onto muscle, with the neuromuscular junction for the chapter on skeletal muscle contraction. - Medicine and pharmacology: Slides that put each drug on its step: SSRIs on serotonin reuptake, acetylcholinesterase inhibitors in the cleft, botulinum toxin on vesicle release, neuromuscular blockers on the acetylcholine receptors. - Research and textbook figures: Schematic panels for neuroscience papers, grant applications and review articles — a synapse with the protein of interest highlighted, drawn at the depth the figure needs. #### Common questions about synapse diagrams **What are the parts of a synapse?** A chemical synapse has three parts: the presynaptic axon terminal, the synaptic cleft and the postsynaptic membrane. The terminal holds synaptic vesicles of neurotransmitter, mitochondria and voltage-gated Ca²⁺ channels; the postsynaptic membrane carries the receptors. A labeled diagram usually adds the neurotransmitter molecules and a reuptake transporter or an enzyme in the cleft. **What are the steps of synaptic transmission?** An action potential reaches the axon terminal; voltage-gated Ca²⁺ channels open and Ca²⁺ flows in; vesicles release neurotransmitter by exocytosis; it diffuses across the cleft; it binds receptors that open ion channels in the postsynaptic membrane; and it is removed by enzymes, reuptake or diffusion. The chemical step from release to response takes about 1 ms. **What is the difference between a chemical and an electrical synapse?** A chemical synapse passes the signal with a neurotransmitter across a cleft of about 20–40 nm; an electrical synapse lets ions flow straight through gap junctions between two cells that almost touch. Chemical synapses are one-way, about 1 ms slower and adjustable; electrical synapses are virtually instantaneous and often two-way. **What is the neuromuscular junction?** The neuromuscular junction is the chemical synapse between a motor neuron and a skeletal muscle fiber. The axon terminal releases acetylcholine, which binds nicotinic acetylcholine receptors on the motor end plate and starts an action potential in the muscle fiber; acetylcholinesterase in the cleft then breaks the acetylcholine down. **Can I get a blank synapse diagram to label?** Yes — view the blank version on this page free, or ask for one and every label is replaced by an empty answer line. The labeled version is the matching answer key, so the two print as a pair. **What does the synaptic cleft do?** It keeps the two cells apart, so the signal has to cross as a chemical — which is what lets a synapse amplify, inhibit or block it. The cleft is about 20–40 nm wide; the neurotransmitter diffuses across it, and enzymes and transporters at its edges clear it away. **Why is calcium needed for neurotransmitter release?** Ca²⁺ entering the axon terminal is the trigger that makes synaptic vesicles fuse with the presynaptic membrane. Without it the action potential still arrives but no neurotransmitter is released, which is why blocking the voltage-gated Ca²⁺ channels stops transmission. **How is a neurotransmitter removed from the synapse?** By enzyme breakdown, by reuptake into the presynaptic terminal or nearby glial cells, or by diffusing out of the cleft. Acetylcholinesterase splits acetylcholine; SSRI antidepressants block serotonin reuptake, so serotonin stays in the cleft longer. **What is the difference between an excitatory and an inhibitory synapse?** An excitatory synapse depolarizes the postsynaptic membrane (an EPSP), moving it toward threshold; an inhibitory synapse hyperpolarizes it (an IPSP), moving it away. Glutamate is the main excitatory neurotransmitter in the brain and GABA the main inhibitory one; whether the neuron fires depends on the sum of all its inputs. #### Sources - Communication Between Neurons — Anatomy and Physiology 2e, section 12.5 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/12-5-communication-between-neurons - How Neurons Communicate — Biology 2e, section 35.2 — OpenStax: https://openstax.org/books/biology-2e/pages/35-2-how-neurons-communicate --- ### Protein Synthesis Diagram — Transcription & Translation URL: https://scientificfigure.com/tools/protein-synthesis-diagram Description: Make a labeled protein synthesis diagram in seconds: transcription, mRNA processing and translation at the ribosome, with tRNA, codons and the central dogma. #### What is a protein synthesis diagram? A protein synthesis diagram shows how a cell turns a gene into a protein in two stages: transcription, where RNA polymerase copies DNA into mRNA, and translation, where a ribosome reads its codons and tRNAs bring the matching amino acids. In eukaryotes the mRNA is processed in between. - Information flows from DNA to RNA to protein. This is the central dogma: transcription makes a messenger RNA copy of a gene, and translation on ribosomes turns that message into a chain of amino acids. - The genetic code is read in triplets. Each three-base codon on the mRNA specifies one amino acid; of the 64 possible codons, 61 code for amino acids and 3 are stop codons, and AUG both codes for methionine and starts translation. - Eukaryotic mRNA is processed before it leaves the nucleus. The pre-mRNA gets a 5′ cap and a poly-A tail of about 200 adenines, and its introns are spliced out so that only the exons remain. - tRNAs are the adaptors. Each tRNA carries one amino acid and has an anticodon that base-pairs with a codon on the mRNA; depending on the species, 40 to 60 kinds of tRNA exist in the cytoplasm. - The ribosome has three tRNA sites. A new tRNA enters the A site, the tRNA holding the growing chain sits in the P site, and empty tRNAs leave from the E site; peptidyl transferase, an RNA-based enzyme in the large subunit, forms each peptide bond. #### Stages of protein synthesis and what happens in each The stages a labeled protein synthesis diagram is normally expected to show, what happens in each, and where in the cell it takes place. This is the default label set unless you ask for a shorter one. - Transcription: initiation — What happens: RNA polymerase binds the promoter and the DNA unwinds | Where it happens: Nucleus (cytoplasm in bacteria) - Transcription: elongation — What happens: RNA polymerase reads the template strand and builds pre-mRNA 5′ to 3′ | Where it happens: Nucleus - Transcription: termination — What happens: The transcript is released and the DNA rewinds | Where it happens: Nucleus - 5′ capping — What happens: A modified guanine cap is added to the front of the pre-mRNA, protecting it and helping ribosomes bind | Where it happens: Nucleus - Poly-A tail — What happens: About 200 adenines are added to the 3′ end | Where it happens: Nucleus - Splicing — What happens: Introns are cut out and exons joined into the mature mRNA | Where it happens: Nucleus - mRNA export — What happens: The mature mRNA leaves the nucleus through a nuclear pore | Where it happens: Nuclear envelope - Translation: initiation — What happens: The small ribosomal subunit binds the mRNA, the initiator tRNA pairs with the AUG start codon, and the large subunit joins | Where it happens: Cytoplasm, on free ribosomes or the rough ER - Translation: elongation — What happens: tRNAs enter the A site, peptide bonds join the amino acids, and the ribosome moves along the mRNA one codon at a time | Where it happens: Ribosome - Translation: termination — What happens: A stop codon reaches the A site, a release factor binds, and the polypeptide is released | Where it happens: Ribosome Courses differ in how finely they split the process. Introductory worksheets often show two steps, transcription and translation, with DNA, mRNA, the ribosome and tRNA; A-level and university courses add RNA processing, the A, P and E sites, the start and stop codons and the three phases of each stage. Name the labels you need and only those are drawn. #### Transcription vs translation: what is the difference? Transcription copies a gene's DNA into messenger RNA; translation reads that mRNA to build a protein. In eukaryotes transcription happens in the nucleus and translation in the cytoplasm; in bacteria, which have no nucleus, both happen in the cytoplasm. - Template — Transcription: DNA (the template strand) | Translation: mRNA - Product — Transcription: RNA — pre-mRNA in eukaryotes | Translation: A polypeptide chain - Where, in eukaryotes — Transcription: Nucleus | Translation: Cytoplasm, on ribosomes - Main machinery — Transcription: RNA polymerase (RNA polymerase II for mRNA) | Translation: Ribosome and tRNAs - Building blocks — Transcription: RNA nucleotides (A, U, G, C) | Translation: Amino acids - Start signal — Transcription: Promoter, such as the TATA box | Translation: AUG start codon - Stop signal — Transcription: Termination sequence | Translation: Stop codon (UAA, UAG or UGA) - Base pairing — Transcription: RNA nucleotides pair with the DNA template, U in place of T | Translation: tRNA anticodons pair with mRNA codons Draw transcription inside the nucleus and translation outside it, with the mRNA crossing the nuclear envelope between them, and show at least one codon paired with its tRNA's anticodon. A diagram with the ribosome translating inside the nucleus, or with T in the mRNA, is the error to check for first. #### Where are protein synthesis diagrams used? Protein synthesis diagrams are used mostly in biology teaching — labeling worksheets, genetics lessons and exam revision — and as schematic panels in molecular biology, medicine and biotechnology. What changes is the depth: DNA, mRNA and a ribosome for a first course, RNA processing and the ribosome's A, P and E sites for a university one. - School biology: Labeling worksheets and revision sheets from middle school through GCSE, A-level, AP Biology and IB. Usually the whole process in order, plus the same drawing blank for students to fill in. - Genetics lessons: Diagrams that tie the genetic code to mutations: how one changed base alters a codon, and how inserting one or two bases shifts the reading frame. - Exam revision: One-page summaries of transcription and translation side by side — which is how exam questions ask about them: name the molecule at X, give the anticodon for a codon, say where each stage happens. - Medicine and biotechnology: Panels on antibiotics that target bacterial ribosomes — tetracycline blocks the A site, chloramphenicol blocks peptide bond formation — and on making proteins from engineered genes. #### Common questions about protein synthesis diagrams **What should a labeled protein synthesis diagram include?** The standard set is the DNA with its template strand, RNA polymerase and the mRNA in the nucleus, a nuclear pore, then the ribosome with its small and large subunits, tRNAs with their anticodons and amino acids, the mRNA codons from the start codon on, and the growing polypeptide chain. That is the default — ask for fewer labels and only those are drawn. **What is the central dogma of molecular biology?** Genetic information flows from DNA to RNA to protein: DNA is copied by replication, transcribed into RNA and translated into protein. Francis Crick stated it in 1958. Retroviruses such as HIV copy RNA back into DNA with reverse transcriptase, and many RNA viruses copy RNA to RNA, but no known process turns a protein sequence back into nucleic acid. **What are the steps of protein synthesis in order?** Transcription, RNA processing and translation. RNA polymerase copies a gene into pre-mRNA; in eukaryotes the pre-mRNA is capped, given a poly-A tail and spliced; the mRNA leaves the nucleus; and a ribosome translates it — initiation at AUG, elongation codon by codon, termination at a stop codon. **What is the difference between a codon and an anticodon?** A codon is a three-base sequence on the mRNA; an anticodon is the matching three-base sequence on a tRNA. The two pair by complementary base pairing: the codon AUG is read by a tRNA with the anticodon UAC, which carries methionine. **What do mRNA, tRNA and rRNA do?** mRNA carries the gene's message from the nucleus to the ribosome; tRNA brings the amino acids and matches them to the codons; rRNA forms the core of the ribosome and catalyzes the peptide bonds. All three are made by transcription. **Where does protein synthesis take place?** Transcription takes place in the nucleus and translation in the cytoplasm, on free ribosomes or ribosomes on the rough endoplasmic reticulum. In bacteria, which have no nucleus, both take place in the cytoplasm. Mitochondria and chloroplasts also have ribosomes of their own. **How many codons are there?** 64: 61 code for amino acids and 3 are stop codons. Most amino acids have more than one codon, which is why the code is called degenerate; AUG is the start codon and also codes for methionine. **How does a mutation change protein synthesis?** A changed base changes the codon, which may then call for a different amino acid, the same one, or a stop. Inserting or deleting one or two bases shifts the reading frame and garbles every codon after it — the effect Crick and Brenner used to show that the code is read in triplets. **Can I make a simple protein synthesis drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: DNA in the nucleus, the mRNA copy, the ribosome, and the amino acids joining into a protein. Five labels or fewer usually covers a middle-school class. **How does the tool keep transcription and translation in the right place and order?** The subject brief is built in. Every render is instructed to follow the standard textbook sequence — each stage drawn in its true order and joined to the next by an arrow — with each label spelled exactly. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a protein synthesis diagram from here in a biology lesson or a thesis?** Yes — the protein synthesis diagrams you generate are yours to use in molecular biology worksheets, lecture slides, lab reports and theses. Export goes up to 4K depending on the model. #### Sources - The Genetic Code — Biology 2e, section 15.1 — OpenStax: https://openstax.org/books/biology-2e/pages/15-1-the-genetic-code - RNA Processing in Eukaryotes — Biology 2e, section 15.4 — OpenStax: https://openstax.org/books/biology-2e/pages/15-4-rna-processing-in-eukaryotes - Ribosomes and Protein Synthesis — Biology 2e, section 15.5 — OpenStax: https://openstax.org/books/biology-2e/pages/15-5-ribosomes-and-protein-synthesis --- ### Calvin Cycle Diagram — Labeled Light-Independent Reactions URL: https://scientificfigure.com/tools/calvin-cycle-diagram Description: Make a labeled Calvin cycle diagram in seconds: carbon fixation, reduction and regeneration with RuBisCO, 3-PGA and G3P, counted over three turns. #### What is a Calvin cycle diagram? A Calvin cycle diagram shows how a chloroplast turns carbon dioxide into sugar in three stages: RuBisCO fixes CO₂ onto RuBP, ATP and NADPH reduce the product to G3P, and most of the G3P is recycled to regenerate RuBP. The cycle runs in the stroma. - It runs in the stroma of the chloroplast. Carbon dioxide enters the leaf through the stomata and diffuses into the stroma, where the light-independent reactions of photosynthesis take place. - Three turns fix three CO₂ and export one G3P. RuBisCO joins 3 CO₂ to 3 RuBP, making 6 molecules of 3-PGA; 6 ATP and 6 NADPH reduce these to 6 G3P; one G3P leaves the cycle and the other five are rebuilt into 3 RuBP. - One G3P costs 9 ATP and 6 NADPH. Six ATP go into reduction and three more into regenerating RuBP; the ADP and NADP⁺ return to the light-dependent reactions to be recharged. - One glucose takes six turns. Each turn fixes one carbon atom, so the cycle runs six times — two G3P — for every six-carbon glucose molecule. - “Dark reaction” is a misleading name. No step uses light directly, but the cycle runs on ATP and NADPH from the light-dependent reactions, which last only millionths of a second, so it is not independent of light and does not run only at night. #### Molecules of the Calvin cycle and what each one does The molecules and the enzyme a labeled Calvin cycle diagram is normally expected to show, what each one is, and its role in the cycle. This is the default label set unless you ask for a shorter one. - Carbon dioxide (CO₂) — What it is: The carbon source, taken in from the air through the stomata | Role in the cycle: Fixed onto RuBP in stage 1, one molecule per turn - RuBisCO — What it is: The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase | Role in the cycle: Catalyzes carbon fixation, joining CO₂ to RuBP - RuBP (ribulose-1,5-bisphosphate) — What it is: A five-carbon sugar with two phosphate groups | Role in the cycle: Takes up CO₂; rebuilt in stage 3 so the cycle can continue - 3-PGA (3-phosphoglycerate) — What it is: A three-carbon acid with one phosphate group | Role in the cycle: The first product: two form for every CO₂ fixed - ATP — What it is: The energy carrier made by the light-dependent reactions | Role in the cycle: Spent in reduction (6 per three turns) and regeneration (3 per three turns) - NADPH — What it is: The electron carrier made by the light-dependent reactions | Role in the cycle: Supplies the electrons that reduce 3-PGA to G3P (6 per three turns) - G3P (glyceraldehyde-3-phosphate) — What it is: A three-carbon sugar phosphate | Role in the cycle: The product: one in six leaves the cycle to build glucose and other compounds; five are recycled - ADP and NADP⁺ — What it is: The spent carriers | Role in the cycle: Return to the thylakoid membranes to be recharged by the light-dependent reactions Courses differ in how much detail they expect. Introductory worksheets often show CO₂ going in, sugar coming out and ATP and NADPH driving the loop; A-level and university courses name RuBisCO, RuBP, 3-PGA and G3P and count the molecules for three turns. Name the labels you need and only those are drawn. #### Light-dependent reactions vs the Calvin cycle: what is the difference? The light-dependent reactions capture light energy on the thylakoid membranes, splitting water, releasing oxygen and making ATP and NADPH; the Calvin cycle spends that ATP and NADPH in the stroma to fix carbon dioxide into sugar. The first turns light into chemical energy; the second stores it in carbon compounds. - Where — Light-dependent reactions: Thylakoid membranes | Calvin cycle: Stroma - Uses light directly — Light-dependent reactions: Yes | Calvin cycle: No, but needs their ATP and NADPH - Inputs — Light-dependent reactions: Light, water, ADP and NADP⁺ | Calvin cycle: CO₂, ATP and NADPH - Outputs — Light-dependent reactions: Oxygen, ATP and NADPH | Calvin cycle: G3P, ADP and NADP⁺ - Key components — Light-dependent reactions: Photosystem II, photosystem I, the electron transport chain and ATP synthase | Calvin cycle: RuBisCO and RuBP - Carbon — Light-dependent reactions: None is fixed | Calvin cycle: CO₂ is fixed into organic molecules - Other names — Light-dependent reactions: Light reactions | Calvin cycle: Light-independent reactions, Calvin-Benson cycle; formerly the dark reaction Draw the two stages as linked halves of one chloroplast: ATP and NADPH flowing from the thylakoids into the stroma, ADP and NADP⁺ flowing back. A diagram where the Calvin cycle gives off oxygen, or where the light reactions take in CO₂, is the error to check for first. #### Where are Calvin cycle diagrams used? Calvin cycle diagrams are used mostly in biology teaching — labeling worksheets, photosynthesis lessons and exam revision — and in plant biology and crop research on how plants fix carbon. What changes is the depth: CO₂ in and sugar out for a first course, every molecule counted for three turns for a university one. - School biology: Labeling worksheets and revision sheets for GCSE, A-level, AP Biology and IB, where the Calvin cycle is the second stage of photosynthesis. Usually the labeled cycle, plus the same drawing blank for students to fill in. - Photosynthesis lessons: Diagrams that join the two stages — the light-dependent reactions on the thylakoids feeding ATP and NADPH to the cycle in the stroma — and set photosynthesis against cellular respiration. - Exam revision: One-page summaries with the molecule counts — which is how exam questions ask about the cycle: how many ATP per G3P, which enzyme fixes carbon, what happens to the other five G3P. - Plant biology and research: Panels on how plants adapt carbon fixation to hot, dry places — cacti take up CO₂ at night with their stomata open, then run the cycle by day — and on improving carbon fixation in crops. #### Common questions about Calvin cycle diagrams **What should a labeled Calvin cycle diagram include?** The standard set is the three stages — carbon fixation, reduction and regeneration — with CO₂, RuBisCO, RuBP, 3-PGA, ATP, ADP, NADPH, NADP⁺ and G3P, the G3P that leaves the cycle, and the molecule counts for three turns. That is the default — ask for fewer labels and only those are drawn. **What is photorespiration?** Photorespiration is what happens when RuBisCO adds O₂ to RuBP instead of CO₂. The product is one 3-PGA and one 2-phosphoglycolate, which the plant has to recycle through its peroxisomes and mitochondria, losing CO₂ and spending ATP on the way. It increases in hot, dry weather; C4 and CAM plants limit it by concentrating CO₂ around RuBisCO. **What are the three stages of the Calvin cycle?** Carbon fixation, reduction and regeneration. In fixation RuBisCO joins CO₂ to RuBP, giving 3-PGA; in reduction ATP and NADPH turn 3-PGA into G3P; in regeneration most of the G3P is rebuilt into RuBP, using more ATP, so the cycle can take in the next CO₂. **Where does the Calvin cycle take place?** In the stroma of the chloroplast, the fluid around the thylakoids. The light-dependent reactions happen on the thylakoid membranes, so the ATP and NADPH they make are released right where the cycle needs them. **What are the inputs and outputs of the Calvin cycle?** For three turns, 3 CO₂, 9 ATP and 6 NADPH go in; one G3P, 9 ADP and 6 NADP⁺ come out. The ADP and NADP⁺ go back to the light-dependent reactions to be recharged; the G3P is used to build glucose and other compounds. **How many turns of the Calvin cycle make one glucose?** Six. Each turn fixes one carbon atom, so three turns make one three-carbon G3P and six turns make the two G3P behind one six-carbon glucose — at a cost of 18 ATP and 12 NADPH. **What does RuBisCO do?** RuBisCO is the enzyme that fixes carbon: it joins each CO₂ to a molecule of RuBP, and each reaction gives two molecules of 3-PGA. Its full name is ribulose-1,5-bisphosphate carboxylase/oxygenase, and it works in the stroma on the RuBP the cycle keeps regenerating. **Why is the Calvin cycle called light-independent?** Because none of its steps uses light directly — but it still depends on light. It runs on the ATP and NADPH made by the light-dependent reactions, which last only millionths of a second. That is why the old name, “dark reaction”, misleads: the cycle does not run only at night. **Can I make a simple Calvin cycle drawing for younger students?** Yes — ask for a simple overview and the diagram drops to the essentials: carbon dioxide going in, ATP and NADPH driving the loop, sugar coming out and the starting molecule rebuilt. Five labels or fewer usually covers a middle-school class. **How does the tool keep the Calvin cycle's stages and molecules in order?** The subject brief is built in. Every render is instructed to follow the standard textbook drawing — each stage in its true order around a closed loop, joined by arrows that name what goes in and out — with each label spelled exactly. Check the labels against your course before printing; the canvas lets you correct any in place. **Can I use a Calvin cycle diagram from here in a lesson or a paper?** Yes — the Calvin cycle diagrams you generate are yours to use in photosynthesis worksheets, biochemistry slides, reports and theses. Export goes up to 4K depending on the model. #### Sources - Using Light Energy to Make Organic Molecules — Biology 2e, section 8.3 — OpenStax: https://openstax.org/books/biology-2e/pages/8-3-using-light-energy-to-make-organic-molecules - The Light-Dependent Reactions of Photosynthesis — Biology 2e, section 8.2 — OpenStax: https://openstax.org/books/biology-2e/pages/8-2-the-light-dependent-reactions-of-photosynthesis --- ### Free Body Diagram Maker & Drawer — Free FBD Creator URL: https://scientificfigure.com/tools/free-body-diagram-maker Description: Draw a correct free body diagram in seconds: every force an arrow from the body, labeled W, N, f, T. Inclines, pulleys, elevators, tension, friction. #### What is a free body diagram? A free body diagram (FBD) shows one object on its own, drawn as a dot or a simple box, with every external force acting on it drawn as an arrow that starts on the object and points the way the force acts. Each arrow carries its symbol — W or mg for weight, N for the normal force, f for friction, T for tension — and the diagram is the first step in applying Newton's second law. - Only forces belong on it. Velocity, acceleration and the net force are not forces acting on the body, so they are not drawn; the net force is what you work out from the diagram. - Every force needs something that exerts it. Weight comes from the Earth, the normal force and friction from a surface in contact, tension from a rope or cable. If nothing is pushing or pulling, there is no arrow — which rules out a “centrifugal force” in an ordinary, non-rotating frame. - The normal force is perpendicular to the surface. On a level floor it points straight up; on an incline at angle θ it tilts with the surface, and with no other force pressing the block into the slope its size is mg cos θ, not mg. - Friction is parallel to the surface. Kinetic friction points opposite to the direction of sliding; static friction points whichever way stops the object from starting to slip. - Tilt the axes on an incline. With x along the slope and y perpendicular to it, only the weight has to be split into components: mg sin θ down the slope and mg cos θ into the surface. #### Forces on a free body diagram and how to draw each one The forces that come up most often in mechanics problems, the symbol each is usually given, and the direction its arrow must point. These are the conventions every diagram here follows unless you ask for others. - Weight (force of gravity) — Symbol: W or mg (also F_g) | How to draw it: Straight down, toward the center of the Earth, on every object with mass - Normal force — Symbol: N (also F_N) | How to draw it: Perpendicular to the contact surface, pushing away from it - Kinetic friction — Symbol: f_k | How to draw it: Parallel to the surface, opposite to the direction of sliding - Static friction — Symbol: f_s | How to draw it: Parallel to the surface, opposite to the way the object would start to slip - Tension — Symbol: T | How to draw it: Along the rope, string or cable, pulling away from the body - Applied force — Symbol: F_app (also F_a or P) | How to draw it: In the direction of the push or pull - Air resistance (drag) — Symbol: F_air or D | How to draw it: Opposite to the object's velocity through the air - Spring force — Symbol: F_spring | How to draw it: Along the spring, back toward its natural length Symbols vary between textbooks. Some courses write F_g and F_N, others W and N, and some write every force as F with a two-letter subscript naming who pushes on whom. Tell the maker which symbols your course uses and only those are drawn. #### Free body diagram vs motion diagram: what is the difference? A free body diagram shows the forces on one object at one instant; a motion diagram shows where the object is at equal time intervals, with its velocity and acceleration arrows. Mixing the two — adding a velocity arrow to a free body diagram — is one of the errors physics teachers mark down most often. - What it shows — Free body diagram: The forces acting on one object | Motion diagram: The object's position at equal time intervals - The arrows are — Free body diagram: Forces, each exerted by something | Motion diagram: Velocity and acceleration - The object is drawn — Free body diagram: Once, as a dot or a simple box | Motion diagram: Several times, as a row of dots - Arrow length — Free body diagram: In proportion to the size of each force | Motion diagram: In proportion to the speed or its change - Answers — Free body diagram: Why does it move this way? (ΣF = ma) | Motion diagram: How does it move? - Belongs on it — Free body diagram: W, N, f, T, F_app | Motion diagram: v and a Newton's second law links the two: the net force from the free body diagram points the same way as the acceleration on the motion diagram. If the arrows on your free body diagram cannot add up to the acceleration you expect, a force is missing or pointing the wrong way. #### Where are free body diagrams used? Free body diagrams are used wherever forces have to be added up — physics classes and exams, engineering statics, biomechanics — because Newton's laws can only be applied once every force on one object is drawn. What changes is the object: a dot for a first course, a beam or a joint with forces at their true points of action later on. - School and college physics: Worksheets, lab write-ups and exam answers in high-school physics, AP Physics, IB, A-level and first-year college mechanics, where a free body diagram is usually the first mark in a forces question. - Homework and exam revision: Blocks on inclines, pulleys, elevators and hanging masses — the standard problems, each drawn once correctly so the equations that follow from it are right too. - Engineering statics: Beams, trusses and frames with reaction forces at their supports, drawn where each force acts so moments can be taken about a point. - Biomechanics and sports science: Forces on a limb, a joint or an athlete — muscle forces, joint reactions, ground reaction force — for lectures, reports and papers. #### Common questions about free body diagrams **What should a free body diagram include?** The object on its own as a dot or a simple box, one arrow for every external force acting on it, each labeled with its symbol, and a coordinate system. Nothing else — no surroundings, no velocity or acceleration arrows, no net force. That is the default; ask for the incline or the rope to be sketched in and they are. **Is a force diagram the same as a free body diagram?** In most courses, yes: both draw the forces on one object as arrows labeled with their symbols, and the two names are used for the same drawing. Where a course does separate them, a force diagram may show the object in its surroundings or several objects at once, while a free body diagram always isolates one object and nothing else. Either way, every arrow is a force exerted by something. **How do you draw a free body diagram step by step?** Isolate the object, find every force on it, then draw and label each as an arrow from the body. Start with its weight; add a normal force and friction for every surface it touches and a tension for every rope or cable; add any push or pull. Then choose axes — along and perpendicular to the surface on an incline — and check that every arrow has something exerting it. **Why is the normal force not vertical on an incline?** Because the normal force is always perpendicular to the surface that exerts it — and an incline's surface is tilted. Drawing it straight up is the most common free body diagram mistake. Its size changes too: with no other force pressing the block into the slope, N = mg cos θ, smaller than the weight. **Should I draw a centrifugal force for an object moving in a circle?** No. In the usual inertial frame nothing exerts a centrifugal force, so it has no arrow. The centripetal force is not an extra arrow either: it is the name for the net inward force made up of the forces already drawn — tension on a swinging ball, friction on a car in a bend, gravity on a satellite. **Do velocity and acceleration go on a free body diagram?** No — only forces do. A body moving to the right does not need a force to the right; a crate sliding at constant speed has balanced forces. If you want to show the direction of motion, write it beside the diagram, not as an arrow on it. **Which way does friction point?** Along the surface, opposite to the sliding. Kinetic friction opposes the motion of the object relative to the surface; static friction opposes the way it would start to slip, so on a block resting on a slope it points up the slope. **Where should the force arrows start?** On the object, pointing the way each force acts. In a particle diagram every arrow starts at the dot or the center of the box — even a push is drawn tail on the body. When turning effects matter, as for a beam or a ladder, draw each force at the point where it acts. **Does it calculate the forces, like a free body diagram solver?** It draws the diagram; the equations stay yours. Give it the numbers — the mass, the angle, a coefficient of friction — and they are written on the drawing, but it does not solve for unknown forces, so check any value before you rely on it. #### Sources - Drawing Free-Body Diagrams — University Physics Volume 1, section 5.7 — OpenStax: https://openstax.org/books/university-physics-volume-1/pages/5-7-drawing-free-body-diagrams - Friction — University Physics Volume 1, section 6.2 — OpenStax: https://openstax.org/books/university-physics-volume-1/pages/6-2-friction --- ### Dichotomous Key Maker — Free Creator & Template URL: https://scientificfigure.com/tools/dichotomous-key-maker Description: What a dichotomous key is and how to make one: numbered couplets, contrasting leads, named organisms, as a branching tree or a list. Free creator and template. #### What is a dichotomous key? A dichotomous key is an identification tool that sorts organisms through a series of choices between two contrasting statements, called couplets; each choice leads either to the next couplet or to the name of the organism. “Dichotomous” means dividing in two, and a well-built key ends every path in exactly one named organism or group. - A couplet is two statements about the same character. “Leaves are needles” against “leaves are broad and flat” is a couplet; “leaves are needles” against “bark is rough” is not, because a specimen could match both or neither. - The two leads must be mutually exclusive. Every specimen fits exactly one lead of each couplet, so the path through the key is never ambiguous. - Leads are numbered in pairs. Couplet 1 has the leads 1a and 1b (some floras write 1 and 1′), and each lead ends either with the number of the next couplet or with a name. - The characters must be visible on the specimen. Number of legs, leaf shape or the presence of a shell work; habitat, behavior or diet do not, because they cannot be checked on the organism in front of you. - It comes in two layouts. A branching tree, like a flowchart, is easiest to follow in class; a numbered couplet list — bracketed or indented — is how field guides and floras print keys, and it fits many more organisms on a page. #### Parts of a dichotomous key and how to write each one The parts every dichotomous key is built from, what each one is, and the rule that keeps it usable. These are the rules every key drawn here follows. - Couplet — What it is: One numbered step of the key: a pair of contrasting statements | How to write it: About one character only, with exactly two options - Lead — What it is: One of the two statements in a couplet | How to write it: Start both leads the same way: “Leaves simple” / “Leaves compound” - Character — What it is: The feature a couplet compares | How to write it: Something visible on the specimen: body parts, counts, shapes, arrangement - Character state — What it is: The form the character takes | How to write it: Contrasting and exact: “six legs” / “eight legs”, measurements rather than “large” and “small” - Go-to number — What it is: The couplet a lead sends you to | How to write it: Always a later couplet, so the key never loops back - Named organism (taxon) — What it is: The name a path ends on | How to write it: One named species or group at the end of each path - Number of couplets — What it is: Set by the number of organisms | How to write it: A key to n organisms has n − 1 couplets: six organisms, five couplets - Layout — What it is: How the couplets are arranged on the page | How to write it: A branching tree for teaching; a bracketed or indented numbered list for field guides Courses differ in how they number leads. Many school keys use 1a and 1b; botanical floras often use 1 and 1′, or indent the second lead under the first. Name the style your course uses and the key is drawn that way. #### Dichotomous key vs cladogram: what is the difference? A dichotomous key identifies an organism from features you can see; a cladogram shows how organisms are related by descent from common ancestors. Both branch in twos, but the groups in a key need not be related at all — “has a shell” puts a snail beside a turtle. - Purpose — Dichotomous key: Identify an unknown organism | Cladogram: Show evolutionary relationships - Branch points — Dichotomous key: Couplets of two contrasting statements | Cladogram: Common ancestors, marked by shared derived traits - Characters used — Dichotomous key: Any visible feature that splits the list cleanly | Cladogram: Traits inherited from a common ancestor - Groups — Dichotomous key: Need not be related | Cladogram: Clades: an ancestor and all its descendants - Read — Dichotomous key: From the top, one choice at a time | Cladogram: From the root out to the tips - Ends in — Dichotomous key: A named organism or group | Cladogram: The organisms being compared Use a key to name a specimen and a cladogram to explain how it is related to others. Grouping a snail with a turtle because both have shells is fine in a key and wrong in a cladogram. #### Where are dichotomous keys used? Dichotomous keys are used wherever organisms have to be named from what they look like — biology classes, field work, microbiology labs and published field guides. What changes is the scale: a handful of classroom animals, or every species in a genus. - School biology: Classification lessons and worksheets in middle-school life science, GCSE, AP Biology and IB, where students both use a key and write their own. - Field work and ecology: Naming the invertebrates from a pond dip or a pitfall trap, or the trees on a nature walk, with a key printed for the site. - Microbiology labs: Identifying an unknown bacterium from its Gram stain, cell shape and biochemical test results, one couplet per test. - Field guides and taxonomy: Floras, field guides and taxonomic papers publish keys to the species of a region or a genus, usually as a numbered couplet list. #### Common questions about dichotomous keys **How do you make a dichotomous key?** List the organisms, pick one visible character that splits them into two groups of about the same size, and write it as two contrasting statements — that is couplet 1. Repeat inside each group, numbering each new couplet, until every group holds one organism and each path ends in its name. Then test the key by running every specimen through it. **What makes a good couplet?** Two statements about the same character that cannot both be true and that anyone can check on the specimen. Word them positively (“wings present” / “wings absent”, not “not winged”), start both the same way, and prefer counts and measurements to “large” and “small”. **What is an example of a dichotomous key?** A key to four animals: 1a Body covered in feathers → bird; 1b Body not covered in feathers → go to 2. 2a Body covered in fur → dog; 2b Body not covered in fur → go to 3. 3a Has fins and scales → fish; 3b Has legs and smooth, moist skin → frog. Four animals, three couplets, each one splitting on a feature you can see. The labeled key on this page is a larger example, six invertebrates in five couplets. **Should I draw a branching tree or a numbered list?** A tree for teaching, a list for anything long. The branching tree shows every path at once and suits a handful of organisms; the numbered couplet list — 1a, 1b, 2a, 2b, each ending in “go to” a number or a name — is the form field guides use and fits dozens of organisms. Ask for either. **How many couplets does a dichotomous key need?** One fewer than the number of organisms. Every couplet splits one group into two, so a key to six organisms has five couplets and a key to twenty has nineteen, however they are arranged. **What do 1a and 1b mean in a dichotomous key?** They are the two leads of couplet 1. You read both, choose the one that fits your specimen, and follow it — either to the couplet number it gives (“go to 2”) or to the name it ends in. **Can a key have three choices at one step?** Then it is no longer dichotomous. A key with three or more choices at a step is polytomous, and a multi-access key lets you use the characters in any order. A dichotomous key always offers exactly two. **Can I make a key for bacteria, rocks or anything else?** Yes — a key can sort anything with features you can check. Bacteria by Gram stain, shape and test results; minerals by hardness and streak; leaves by shape and arrangement. Describe what you are sorting and the key is drawn for it. **Does the maker write the couplets for me?** Yes, if you only name the organisms — it drafts a key from their standard textbook features. Check each couplet against your own specimens before handing it out, or give your own couplets and they are drawn exactly as written. #### Sources - Dichotomous Keys — Introduction to Botany (Shipunov), section 10.3 — LibreTexts: https://bio.libretexts.org/Bookshelves/Botany/Introduction_to_Botany_(Shipunov)/10:_Methods_of_Taxonomy_and_Diagnostics/10.03:_Dichotomous_keys - Using a Dichotomous Key — Botany Lab Manual (Morrow), section 22.6 — LibreTexts: https://bio.libretexts.org/Bookshelves/Botany/Botany_Lab_Manual_(Morrow)/22:_Gymnosperms/22.6:_Using_a_Dichotomous_Key --- ### Notch Signaling Pathway Diagram — Labeled, with NICD, Free URL: https://scientificfigure.com/tools/notch-signaling-pathway Description: Make a free labeled Notch signaling pathway diagram: DSL ligand, Notch receptor, ADAM10 and γ-secretase cuts, NICD, CSL (RBPJ), HES/HEY, lateral inhibition. #### What is the Notch signaling pathway? The Notch signaling pathway is a contact-dependent pathway: a Delta-like or Jagged ligand on one cell binds the Notch receptor on its neighbour, ADAM10 and γ-secretase cut the receptor, and the freed Notch intracellular domain (NICD) enters the nucleus to switch on HES and HEY genes with CSL (RBPJ) and MAML. The receptor fragment itself carries the signal, with no kinase cascade or second messenger in between. - Mammals have four Notch receptors and five canonical ligands. NOTCH1–4 are activated by the Delta-like ligands DLL1 and DLL4 and the Jagged ligands JAG1 and JAG2; DLL3 works mainly by cis-inhibition rather than by activating Notch. - Notch is cut three times. Furin cleaves the new receptor at S1 in the Golgi, making the mature heterodimer; after ligand binding, ADAM10 cuts at S2 just outside the membrane, and γ-secretase, whose catalytic subunit is presenilin, cuts at S3 inside it to release NICD. - The ligand has to pull. Binding alone is not enough: the ubiquitin ligases Mindbomb or Neuralized tag the bound ligand, the sending cell endocytoses it, and that pull unfolds the receptor's negative regulatory region so ADAM10 can reach the S2 site. - CSL (RBPJ) is a switch. Without NICD it sits on target genes with co-repressors and histone deacetylases; NICD displaces them and recruits MAML and histone acetyltransferases such as p300 to turn HES1, HES5, HEY genes and MYC on. - Each signal is short-lived. CDK8 phosphorylates NICD's PEST domain and the ubiquitin ligase FBXW7 marks it for destruction, resetting the pathway — PEST and FBXW7 mutations that stop this are common in T-cell acute lymphoblastic leukemia. #### Components of the Notch signaling pathway and what each one does The molecules a labeled Notch pathway diagram is normally expected to show, in the order the signal passes through them. This is the default label set unless you ask for a shorter one. - DSL ligand (DLL1, DLL4, JAG1, JAG2) — What it does: Transmembrane ligand that binds Notch on the neighbouring cell | Where to draw it: In the sending cell's membrane, facing the gap - Mindbomb or Neuralized — What it does: Ubiquitin ligases that tag the bound ligand for endocytosis, which pulls on the receptor | Where to draw it: Inside the sending cell, at the ligand's tail - Notch receptor (NOTCH1–4) — What it does: Single-pass receptor, held as a two-part heterodimer after S1 cleavage by furin | Where to draw it: Spanning the receiving cell's membrane - Fringe — What it does: Golgi glycosyltransferase that extends O-fucose on Notch's EGF repeats, favouring Delta over Jagged | Where to draw it: In the receiving cell's Golgi (optional) - ADAM10 (S2 cleavage) — What it does: Metalloprotease that sheds the extracellular domain once the pull exposes the S2 site, leaving NEXT | Where to draw it: Just outside the receiving cell's membrane - γ-Secretase (S3 cleavage) — What it does: Intramembrane protease — presenilin with nicastrin, PEN-2 and APH-1 — that cuts NEXT to release NICD | Where to draw it: Within the membrane bilayer - NICD — What it does: Notch intracellular domain; carries the signal itself into the nucleus | Where to draw it: Arrow from the membrane through the cytoplasm to the nucleus - CSL (RBPJ) with co-repressors — What it does: DNA-binding protein that keeps target genes off while NICD is absent | Where to draw it: On the DNA in the nucleus - MAML (Mastermind-like) — What it does: Co-activator recruited by NICD and CSL; brings in p300 | Where to draw it: Stacked on NICD and CSL on the DNA - HES and HEY genes — What it does: Main targets; they encode repressors that carry out Notch's effects | Where to draw it: Downstream of the complex, at the bottom Courses differ in how many of these they expect. An introductory figure stops at ligand, receptor, NICD and target genes; a cell biology course adds ADAM10, γ-secretase, CSL (RBPJ) and MAML; advanced courses add furin, Fringe and Mindbomb. Sources also differ on the S2 enzyme: ADAM17 cuts Notch in the test tube, but ligand-induced cleavage in living cells depends on ADAM10. #### Notch vs Wnt signaling: what is the difference? Notch signaling needs direct contact — a membrane-bound ligand on one cell triggers cuts in the receptor on the next, and the receptor fragment itself goes to the nucleus — whereas canonical Wnt signaling uses a secreted ligand that saves β-catenin from its destruction complex. Both steer cell fate in development and stem cells, and both are rewired in cancer. - Ligand — Notch signaling: Membrane-bound DSL ligands: DLL1, DLL4, JAG1, JAG2 | Wnt (canonical) signaling: Secreted, lipid-modified WNT glycoproteins — 19 in humans - Range — Notch signaling: Contact-dependent (juxtacrine): only touching cells | Wnt (canonical) signaling: Short and long range, as a gradient around the source - Receptor — Notch signaling: NOTCH1–4, single-pass transmembrane | Wnt (canonical) signaling: One of 10 Frizzled receptors with the LRP5/6 co-receptor - How the signal passes — Notch signaling: Proteolysis: S2 by ADAM10, S3 by γ-secretase | Wnt (canonical) signaling: The destruction complex (APC, Axin, GSK3, CK1) is switched off - Messenger to the nucleus — Notch signaling: NICD, a fragment of the receptor | Wnt (canonical) signaling: β-catenin, a cytoplasmic protein spared from degradation - Nuclear partner — Notch signaling: CSL (RBPJ) with MAML | Wnt (canonical) signaling: TCF/LEF - Off state — Notch signaling: CSL (RBPJ) represses targets with co-repressors | Wnt (canonical) signaling: β-catenin is phosphorylated and destroyed by the proteasome - Signature cancer — Notch signaling: NOTCH1 mutations in more than 50% of T-ALL | Wnt (canonical) signaling: A Wnt-pathway mutation in about 90% of sporadic colorectal cancers Draw Notch as two cells touching, with the ligand fixed in one membrane; draw Wnt with the ligand free in the space between cells. The two pathways cross-talk — NICD can act on Wnt signaling — but keep their nuclear partners apart: CSL for Notch, TCF/LEF for Wnt. #### Where are Notch signaling pathway diagrams used? Notch pathway diagrams are used in cell and developmental biology teaching, in exam revision and as schematic panels in stem-cell, vascular and cancer research. The depth changes with the audience: four labels for a first course, every cleavage and co-factor for a graduate one. - Cell biology courses: Lecture slides on cell–cell signaling that set Notch beside Wnt, Hedgehog and TGF-β: a membrane-bound ligand, activation by proteolysis and a receptor fragment that works as a transcription co-activator. - Developmental biology: Figures of lateral inhibition — hair cells and supporting cells in the inner ear, tip and stalk cells in growing blood vessels — and of somite segmentation, where pulses of Notch activity mark each new somite. - Cancer and hematology: Panels on NOTCH1 activating mutations in T-ALL, FBXW7 loss, and drugs that act on the pathway, from γ-secretase inhibitors to DLL3-targeted antibodies in small-cell lung cancer. - Research figures and grant proposals: Schematics that mark where a mutation, a knockout or an inhibitor acts — ADAM10, γ-secretase, CSL (RBPJ) or MAML — directly on the pathway. #### Common questions about the Notch signaling pathway **What should a labeled Notch signaling pathway diagram include?** The standard set is the signal-sending cell with a DSL ligand (Delta-like or Jagged), the signal-receiving cell with the Notch receptor, S2 cleavage by ADAM10, S3 cleavage by γ-secretase, the released NICD, and in the nucleus CSL (RBPJ), MAML and the HES/HEY target genes. Many figures add S1 cleavage by furin in the Golgi and the co-repressors CSL holds before NICD arrives. **What are the steps of Notch signaling?** Five steps: a ligand on one cell binds Notch on the next; the sending cell endocytoses the ligand and pulls; ADAM10 cuts Notch at S2; γ-secretase cuts it at S3 inside the membrane; and NICD enters the nucleus, where it joins CSL (RBPJ) and MAML to switch on target genes. Before any of this, furin has already cut the new receptor once, at S1 in the Golgi. **What does γ-secretase do in Notch signaling?** γ-Secretase makes the last cut, S3, inside the membrane, releasing NICD from the stub that ADAM10 leaves behind. It is a four-part complex — presenilin 1 or 2 as the catalytic subunit, with nicastrin, PEN-2 and APH-1 — and it also cleaves amyloid precursor protein, the substrate linked to Alzheimer's disease. **What is lateral inhibition in Notch signaling?** Lateral inhibition is how Notch splits a group of equivalent cells into two fates: a cell that sends slightly more Delta activates Notch in its neighbours, Notch signaling lowers their own Delta, and the difference grows until the first cell takes one fate and the cells around it another. In the inner ear this leaves each hair cell surrounded by supporting cells. **What is cis-inhibition of Notch?** Cis-inhibition is Notch being blocked by ligand in its own cell: a Delta or Jagged ligand in the same membrane binds the receptor and stops it responding to ligand on neighbours. DLL3 seems to act only this way, and together with activation in trans it pushes a cell into a clear sending or receiving state. **What does Fringe do to Notch?** Fringe enzymes — Lunatic, Manic and Radical Fringe — extend the O-fucose sugars on Notch's EGF repeats in the Golgi, which makes NOTCH1 respond more to Delta-like ligands than to Jagged. The modification tunes the signal; it is not required for the receptor to mature. **How is Notch signaling involved in cancer?** Activating NOTCH1 mutations occur in more than 50% of T-cell acute lymphoblastic leukemias (T-ALL), mostly in the heterodimerization domain, which lets the receptor fire without ligand, and in the PEST domain, which keeps NICD from being degraded. In other tissues, such as squamous cell carcinomas, Notch acts as a tumor suppressor instead. **What are γ-secretase inhibitors used for?** γ-Secretase inhibitors (GSIs) block the S3 cut and so shut Notch signaling down; the FDA approved one, nirogacestat, for progressing desmoid tumors in November 2023. An early GSI trial in T-ALL was halted by severe diarrhea — the gut lining depends on Notch, and the enzyme has many substrates besides Notch. #### Sources - Signaling by NOTCH1 — pathway R-HSA-1980143 — Reactome: https://reactome.org/content/detail/R-HSA-1980143 - Notch signaling pathway — KEGG PATHWAY hsa04330 — KEGG: https://www.kegg.jp/entry/hsa04330 - Notch signaling pathway: architecture, disease, and therapeutics (Zhou et al., 2022) — Signal Transduction and Targeted Therapy: https://www.nature.com/articles/s41392-022-00934-y - FDA approves nirogacestat for desmoid tumors (2023) — U.S. Food and Drug Administration: https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-nirogacestat-desmoid-tumors --- ### TGF-β Signaling Pathway Diagram — Labeled TGF-β/SMAD, Free URL: https://scientificfigure.com/tools/tgf-beta-signaling-pathway Description: Make a labeled TGF-β signaling pathway diagram: TGF-beta, type II and ALK5 receptors, SMAD2/3, SMAD4 and SMAD7 feedback. Free, with non-SMAD branches. #### What is the TGF-β signaling pathway? The TGF-β signaling pathway carries a signal from transforming growth factor beta at the cell surface to the nucleus: TGF-β binds the type II receptor (TGFBR2), which phosphorylates the type I receptor ALK5 (TGFBR1); ALK5 phosphorylates SMAD2 and SMAD3, which join SMAD4 and enter the nucleus to regulate target genes. SMAD7, one of those targets, turns the receptor back down. - TGF-β is made in a latent form. Furin cuts the precursor, but the latency-associated peptide (LAP) stays wrapped around the mature dimer and LTBPs anchor it in the extracellular matrix; integrins such as αvβ6 and αvβ8, proteases, thrombospondin-1 and acid release the active cytokine. - Both receptors are serine/threonine kinases. TGF-β binds TGFBR2 first; TGFBR2 then recruits TGFBR1 (ALK5) and phosphorylates its glycine- and serine-rich GS domain, and the active complex holds two type II and two type I receptors. - SMAD2 and SMAD3 are the R-SMADs; SMAD4 is the only co-SMAD. The adaptor SARA presents SMAD2/3 to ALK5, which phosphorylates two serines at their C-terminus; phosphorylated R-SMADs then form a complex with SMAD4 that moves into the nucleus. - The pathway switches itself off. The SMAD2/3–SMAD4 complex induces SMAD7, which competes with SMAD2/3 for ALK5 and brings the ubiquitin ligases SMURF1, SMURF2 and NEDD4L to the receptor to have it degraded. - The same signal suppresses early tumours and promotes late ones. In normal and pre-malignant cells TGF-β halts the cell cycle by inducing p15 and p21 and repressing MYC; in advanced carcinomas it drives epithelial–mesenchymal transition, invasion and metastasis. #### Components of the TGF-β signaling pathway and what each one does The molecules a labeled TGF-β pathway diagram is normally expected to show, in the order the signal passes through them. This is the default label set unless you ask for a shorter one. - Latent TGF-β complex (LAP, LTBP) — What it does: Keeps mature TGF-β inactive and stores it in the extracellular matrix | Where to draw it: At the top, in the extracellular space - Activators (integrins αvβ6 and αvβ8, proteases) — What it does: Release the active TGF-β dimer from LAP | Where to draw it: Beside the latent complex - TGF-β dimer — What it does: The active ligand — TGF-β1, TGF-β2 or TGF-β3 | Where to draw it: Above the membrane, bound to the receptors - Type II receptor (TGFBR2) — What it does: Kinase that binds TGF-β first and phosphorylates the type I receptor | Where to draw it: Spanning the membrane - Type I receptor (ALK5, TGFBR1) — What it does: Kinase switched on by phosphorylation of its GS domain; phosphorylates SMAD2 and SMAD3 | Where to draw it: Spanning the membrane beside TGFBR2, with a circled P - SARA — What it does: Adaptor that presents SMAD2/3 to ALK5 | Where to draw it: Just under the membrane, beside ALK5 — strictly on early endosomes - SMAD2 and SMAD3 (R-SMADs) — What it does: Phosphorylated by ALK5 on two C-terminal serines, then released | Where to draw it: In the cytoplasm, each with a circled P - SMAD4 (co-SMAD) — What it does: Shared partner that forms the SMAD2/3–SMAD4 complex | Where to draw it: In the cytoplasm, joining the R-SMADs - Partner transcription factors — What it does: DNA-binding partners such as SP1 and FOXO, and co-activators such as p300, that choose the genes | Where to draw it: On the DNA in the nucleus - Target genes — What it does: PAI-1 (SERPINE1), p15 (CDKN2B), p21 (CDKN1A), collagen (COL1A2), JUNB and SMAD7 on; MYC off | Where to draw it: In the nucleus, at the bottom - SMAD7 with SMURF1/2 — What it does: Inhibitory SMAD that blocks ALK5 and has it degraded | Where to draw it: A flat-headed bar from the nucleus back to ALK5 Courses differ in depth. An introductory figure shows TGF-β, the two receptors, SMAD2/3, SMAD4 and target genes; a cell biology course adds SARA, SMAD7 and SMURFs; advanced courses add the latent complex and the non-SMAD branches — TAK1 to p38 and JNK, PI3K to AKT. Many textbooks draw SMAD phosphorylation at the plasma membrane, while Reactome places it on early endosomes after the receptors are internalized. #### TGF-β vs BMP signaling: what is the difference? TGF-β and BMP signaling use the same machinery — a type II receptor that phosphorylates a type I receptor, R-SMADs and SMAD4 — but TGF-β signals through ALK5 and SMAD2/3, while BMPs signal through ALK2, ALK3 or ALK6 and SMAD1/5/8. Both belong to the TGF-β family, which has 33 members in humans. - Ligands — TGF-β branch: TGF-β1, TGF-β2, TGF-β3 (activin and Nodal use the same SMADs) | BMP branch: BMP2, BMP4, BMP6, BMP7, GDF5 and others - Type II receptor — TGF-β branch: TGFBR2 | BMP branch: BMPR2, ACVR2A, ACVR2B - Type I receptor — TGF-β branch: ALK5 (TGFBR1) | BMP branch: ALK3 (BMPR1A), ALK6 (BMPR1B), ALK2 (ACVR1); ALK1 for BMP9 and BMP10 - Binding order — TGF-β branch: Binds the type II receptor first | BMP branch: Can bind type I receptors alone; both types together bind far more tightly - R-SMADs — TGF-β branch: SMAD2, SMAD3 | BMP branch: SMAD1, SMAD5, SMAD8 - Co-SMAD — TGF-β branch: SMAD4 | BMP branch: SMAD4 - Anchoring adaptor — TGF-β branch: SARA | BMP branch: Endofin - DNA elements — TGF-β branch: Mainly the SMAD-binding element (CAGAC) | BMP branch: GC-rich elements as well as the SMAD-binding element - Extracellular control — TGF-β branch: LAP keeps TGF-β latent | BMP branch: Noggin and gremlin 1 trap BMPs - Typical roles — TGF-β branch: Growth arrest, extracellular matrix, immune regulation, fibrosis | BMP branch: Bone and cartilage formation; heart, kidney and blood vessel development Draw the two branches sharing SMAD4 and nothing else below the receptors. The classic error is SMAD1/5/8 under ALK5 or SMAD2/3 under a BMP receptor. High TGF-β concentrations can also engage ALK1 in endothelial cells, but that is an exception, not the textbook default. #### Where are TGF-β signaling pathway diagrams used? TGF-β pathway diagrams are used in cell biology and pathology teaching, and as schematic panels in fibrosis, cancer and immunology research. A first course needs the receptors and SMADs; a research figure usually adds the latent complex, the feedback loop or a drug target. - Cell biology courses: Receptor serine/threonine kinases set beside receptor tyrosine kinases: ligand, type II and type I receptors, SMADs and the nucleus, with the SMAD7 loop as the worked example of negative feedback. - Fibrosis research: Figures of fibroblasts turning into myofibroblasts under TGF-β — collagen, fibronectin, PAI-1 and α-smooth muscle actin — in lung, kidney, liver and skin fibrosis. - Cancer biology: Panels on the switch from tumour suppressor to tumour promoter: p15, p21 and MYC repression early, EMT, invasion and metastasis late, and drugs such as the ALK5 kinase inhibitor galunisertib. - Research figures and grant proposals: Schematics marking where a mutation or drug acts — TGFBR2 or SMAD4 loss, ALK5 inhibitors, integrin blockade — directly on the pathway. #### Common questions about the TGF-β signaling pathway **What should a labeled TGF-β signaling pathway diagram include?** The standard set is TGF-β, the type II receptor (TGFBR2), the type I receptor ALK5 (TGFBR1) with its phosphorylation, SMAD2 and SMAD3 with circled Ps, SMAD4, the SMAD complex entering the nucleus, target genes, and SMAD7 feeding back to the receptor. Fuller figures add the latent complex (LAP, LTBP), SARA and the SMURF ubiquitin ligases. **What are the steps of the TGF-β/SMAD pathway?** Six steps: active TGF-β is released from its latent complex; it binds TGFBR2; TGFBR2 recruits and phosphorylates ALK5; ALK5 phosphorylates SMAD2 and SMAD3; phospho-SMAD2/3 bind SMAD4; and the complex enters the nucleus to regulate target genes with partner transcription factors. SMAD7, made in response, then turns the receptor down. **Is TGF-beta the same as TGF-β?** Yes — TGF-beta, TGF-β and TGF-b are three spellings of transforming growth factor beta. The name covers three human isoforms, TGF-β1, TGF-β2 and TGF-β3; pathway databases such as Reactome draw TGF-β1. **What does SMAD7 do?** SMAD7 is an inhibitory SMAD that shuts TGF-β signaling down: it binds the activated ALK5 receptor, keeps SMAD2/3 from docking, and recruits SMURF1, SMURF2 or NEDD4L to ubiquitinate the receptor for degradation. It also brings in the phosphatase PP1 to remove ALK5's phosphates. Because SMAD2/3–SMAD4 switch the SMAD7 gene on, this is a negative feedback loop. **What are the target genes of TGF-β?** Few are shared by every cell type — the feedback regulators SMAD7 and SKIL (SnoN) are the main exceptions. Well-known targets that depend on the cell include PAI-1 (SERPINE1), the CDK inhibitors p15 (CDKN2B) and p21 (CDKN1A), collagen type I (COL1A2), JUNB and SNAIL, while MYC is repressed. **Why is TGF-β both a tumour suppressor and a tumour promoter?** Because its effect depends on the cell: in normal and early tumour cells TGF-β halts the cell cycle by inducing p15 and p21 and repressing MYC, but advanced carcinomas that have lost this cytostatic arm use the remaining signal for epithelial–mesenchymal transition, invasion and metastasis. Deleting CDKN2B or weakening SMAD partners such as FOXO is one way tumours make the switch. **How does TGF-β cause fibrosis?** Excess TGF-β signaling drives fibroblasts to become myofibroblasts that make collagen, fibronectin and PAI-1 and express α-smooth muscle actin, so extracellular matrix builds up. In mice, removing SMAD3 or raising SMAD7 protects against experimental lung fibrosis. **What is non-canonical (non-SMAD) TGF-β signaling?** Non-canonical signaling is the set of SMAD-independent branches the same receptors switch on: TRAF proteins activate TAK1, which leads to p38 and JNK, and other routes activate ERK, PI3K–AKT, RHO GTPases and NF-κB. Most figures draw them as one side branch from the receptors. #### Sources - Signaling by TGF-beta Receptor Complex — pathway R-HSA-170834 — Reactome: https://reactome.org/content/detail/R-HSA-170834 - TGF-beta signaling pathway — KEGG PATHWAY hsa04350 — KEGG: https://www.kegg.jp/entry/hsa04350 - TGFβ signalling in context (Massagué, 2012) — Nature Reviews Molecular Cell Biology: https://www.nature.com/articles/nrm3434 - TGF-β signaling in health, disease and therapeutics (Deng et al., 2024) — Signal Transduction and Targeted Therapy: https://www.nature.com/articles/s41392-024-01764-w --- ### Action Potential Graph — Labeled Diagram, Neuron & Cardiac URL: https://scientificfigure.com/tools/action-potential-graph Description: Make a labeled action potential graph in seconds: resting potential, threshold, depolarization, repolarization and hyperpolarization, neuron or cardiac. #### What is an action potential graph? An action potential graph plots a neuron's membrane potential in millivolts against time in milliseconds: from a resting potential of about −70 mV the membrane depolarizes past a threshold of about −55 mV, spikes to about +30 mV, repolarizes, dips briefly below rest and returns to −70 mV. Each phase is labeled with the ion channels that drive it. - The whole spike lasts about 1 to 2 milliseconds in a neuron. The membrane potential swings about 100 mV, from −70 mV at rest to about +30 mV at the peak, and is back at rest a few milliseconds later. - Voltage-gated Na⁺ channels drive depolarization. Once a stimulus brings the membrane to about −55 mV they open, Na⁺ rushes in and the rise feeds itself — a positive-feedback loop that makes the upstroke almost vertical. - Voltage-gated K⁺ channels drive repolarization. They open more slowly than the Na⁺ channels, about when the Na⁺ channels inactivate at the peak, so K⁺ flows out and the membrane potential falls back. - The undershoot comes from K⁺ channels that close late. Potassium keeps leaving for a moment after rest is reached, pulling the membrane below −70 mV toward the K⁺ equilibrium potential of about −90 mV before the Na⁺/K⁺ pump and leak channels restore rest. - Action potentials are all-or-none. A stimulus that does not reach threshold produces no spike, and every stimulus that does produces the same spike to the same peak; a stronger stimulus fires more spikes per second, not bigger ones. #### Phases of the action potential: ion channels and membrane potential The phases a labeled action potential graph is normally expected to show, the ion channel event behind each one, and where it sits on the voltage axis. This is the default label set unless you ask for a shorter one. - Resting potential — What the ion channels do: Voltage-gated channels are closed; K⁺ leak channels and the Na⁺/K⁺ pump hold the membrane steady | Membrane potential: About −70 mV - Stimulus — What the ion channels do: A graded potential, for example from a synapse, lets positive charge in and depolarizes the membrane | Membrane potential: From −70 mV toward −55 mV - Threshold — What the ion channels do: Enough voltage-gated Na⁺ channels open for the rise to become self-sustaining | Membrane potential: About −55 mV - Depolarization (rising phase) — What the ion channels do: Voltage-gated Na⁺ channels open fully and Na⁺ rushes into the cell | Membrane potential: From −55 mV up through 0 mV - Peak (overshoot) — What the ion channels do: Na⁺ channels inactivate as the slower voltage-gated K⁺ channels open | Membrane potential: About +30 mV - Repolarization (falling phase) — What the ion channels do: K⁺ flows out through the open voltage-gated K⁺ channels | Membrane potential: From the peak back down toward −70 mV - Hyperpolarization (undershoot) — What the ion channels do: The K⁺ channels close late, so K⁺ keeps leaving for a moment | Membrane potential: Briefly below −70 mV - Return to resting potential — What the ion channels do: The K⁺ channels close; leak channels and the Na⁺/K⁺ pump restore rest | Membrane potential: Back to about −70 mV - Absolute refractory period — What the ion channels do: Na⁺ channels are open or inactivated, so no stimulus can start a second spike | Membrane potential: From threshold through the peak and most of the fall - Relative refractory period — What the ion channels do: Some Na⁺ channels have reset but K⁺ is still leaving, so only a stronger stimulus works | Membrane potential: The end of the fall and the undershoot Courses differ in how many phases they name. Introductory worksheets label the resting potential, threshold, depolarization, repolarization and hyperpolarization; A-level, AP and university courses add the stimulus, the peak, the channel events and both refractory periods, and some textbooks put the peak at +40 mV rather than +30 mV. Name the labels and values you need and only those are drawn. #### Graded potential vs action potential: what is the difference? A graded potential is a small, local change in membrane potential whose size follows the strength of the stimulus and fades with distance; an action potential is an all-or-none spike to about +30 mV that fires only at threshold and travels the length of the axon without shrinking. Graded potentials on the dendrites and cell body add up at the start of the axon, and an action potential fires there only if their sum reaches threshold. - Size — Graded potential: Varies with the strength of the stimulus | Action potential: Always the same, about 100 mV from rest to peak (all-or-none) - Direction — Graded potential: Depolarizing or hyperpolarizing | Action potential: Always depolarizes, then repolarizes - Threshold — Graded potential: None — any stimulus produces one | Action potential: Fires only when the membrane reaches about −55 mV - Over distance — Graded potential: Fades within a short distance of where it starts | Action potential: Regenerated along the axon at full strength - Where it happens — Graded potential: Dendrites, cell body and sensory receptors | Action potential: The axon, from its initial segment to the axon terminals - Summation and refractory period — Graded potential: Can add together; no refractory period | Action potential: Cannot add together; followed by a refractory period On a graph, a graded potential is a small bump that stays below the threshold line, or a dip below rest; an action potential is the tall spike that crosses threshold, overshoots 0 mV and undershoots rest. If a drawing shows spikes of different heights for different stimuli, it is showing graded potentials, not action potentials. #### Where are action potential graphs used? Action potential graphs are used mostly in biology and physiology teaching — labeling worksheets, exam revision and lecture slides — and in nursing, medical and pharmacology courses that show how drugs and electrolytes change the curve. What changes is the depth: five phase names for a first course, every channel event and both refractory periods for a medical one. - School biology: Labeling worksheets and revision sheets for GCSE, A-level, AP Biology and IB, where the action potential is the core of the nerve impulse. Usually the labeled graph, plus the same graph blank for students to fill in. - Anatomy, physiology and nursing: A&P lectures and nursing courses that tie each phase to its ion — why a high or low blood potassium changes how excitable nerves and heart muscle are, and how the cardiac action potential lines up with the ECG. - Medicine and pharmacology: Slides that put each drug on the phase it changes: local anesthetics and class I antiarrhythmics blocking the Na⁺ channels of the upstroke, class III antiarrhythmics blocking K⁺ channels and lengthening repolarization. - Research and textbook figures: Schematic panels for electrophysiology papers, theses and textbook chapters — a clean reference trace beside recorded data, with the phases and reference levels marked. #### Common questions about action potential graphs **What are the 5 phases of an action potential?** Most courses name five: the resting potential, threshold, depolarization, repolarization and hyperpolarization (the undershoot), after which the membrane returns to rest. Some count the stimulus or the peak as a phase instead of threshold. On the graph they run in that order from left to right, all within about 2 ms in a neuron. **What should a labeled action potential graph include?** Membrane potential (mV) on the vertical axis and time (ms) on the horizontal axis, dashed lines for the resting potential (−70 mV) and threshold (−55 mV), and the stimulus, depolarization, peak (+30 mV), repolarization, hyperpolarization and return to rest on one spike. A&P and medical courses add the Na⁺ and K⁺ channel events and the absolute and relative refractory periods. That is the default — ask for fewer labels and only those are drawn. **What is the resting membrane potential?** The voltage across a neuron’s membrane when it is not firing, about −70 mV, inside negative to outside. It comes mainly from K⁺ leaking out through open leak channels, down a gradient of about 140 mM inside to 4 to 5 mM outside; the Na⁺/K⁺ pump, moving 3 Na⁺ out and 2 K⁺ in per ATP, keeps the gradients from running down. Heart and skeletal muscle cells rest nearer −90 mV. **Why does the membrane potential overshoot to +30 mV?** Because Na⁺ keeps flowing in after the inside of the membrane passes 0 mV, pushed by its steep concentration gradient. The membrane heads toward the Na⁺ equilibrium potential of about +60 mV, but the Na⁺ channels inactivate and the K⁺ channels open first, so the peak stops near +30 mV. **What is the refractory period?** The time after a spike when the membrane cannot fire again (absolute refractory period) or needs a stronger than normal stimulus to fire (relative refractory period). The absolute period lasts while the Na⁺ channels are open or inactivated; the relative period follows while K⁺ is still leaving. It keeps spikes separate and makes the impulse travel one way along the axon. **What happens during depolarization and repolarization?** In depolarization, voltage-gated Na⁺ channels open and Na⁺ rushes in, so the inside of the cell turns from −70 mV to about +30 mV; in repolarization, voltage-gated K⁺ channels open and K⁺ flows out, bringing it back down. Na⁺ moves in on the rising edge of the graph and K⁺ moves out on the falling edge. **What causes hyperpolarization after an action potential?** The voltage-gated K⁺ channels close a little late, so K⁺ keeps leaving the cell after the membrane is back at −70 mV. The potential dips below rest toward the K⁺ equilibrium potential, then the channels close and leak channels and the Na⁺/K⁺ pump return it to −70 mV. **What is the threshold potential?** The membrane potential, about −55 mV in a typical neuron, at which enough voltage-gated Na⁺ channels open for depolarization to keep itself going. Below it, a stimulus fades as a graded potential; at or above it, a full action potential fires — the all-or-none rule. **What is the difference between a neuron and a cardiac action potential?** A ventricular muscle action potential lasts about 250 to 300 ms instead of about 2 ms, starts from about −90 mV instead of −70 mV and has a long plateau (phase 2) while Ca²⁺ enters through slow channels. The plateau gives heart muscle a refractory period of about 250 ms, so it cannot be re-excited before it has contracted. #### Sources - The Action Potential — Anatomy and Physiology 2e, section 12.4 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/12-4-the-action-potential - Cardiac Muscle and Electrical Activity — Anatomy and Physiology 2e, section 19.2 — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/19-2-cardiac-muscle-and-electrical-activity --- ### Wiggers Diagram Maker — Labeled Cardiac Cycle Diagram URL: https://scientificfigure.com/tools/wiggers-diagram Description: Draw a labeled Wiggers diagram: aortic, ventricular and atrial pressure, ventricular volume, ECG and heart sounds, with the 4 valve events and 7 phases. #### What is a Wiggers diagram? A Wiggers diagram is the standard cardiac cycle diagram in physiology: aortic, left ventricular and left atrial pressure, left ventricular volume, the ECG and the heart sounds drawn as stacked traces against one time axis for a single heartbeat. Lining them up shows why each valve opens or closes — where two pressure traces cross — and what the volume, the ECG and the sounds are doing at that moment. It is named after the American physiologist Carl J. Wiggers. - One cardiac cycle lasts about 0.8 s at 75 beats per minute. Ventricular systole takes about 270 ms of it and ventricular diastole about 430 ms; when the heart rate rises it is mostly diastole that shortens. - Valves open and close where the pressure traces cross. The mitral valve closes when ventricular pressure rises above atrial pressure, the aortic valve opens when it rises above aortic pressure, and the reverse crossings close the aortic valve and open the mitral valve. - The left ventricle holds about 130 mL at the end of diastole and about 50–60 mL at the end of systole. The difference, about 70–80 mL, is the stroke volume; divided by the end-diastolic volume it gives an ejection fraction of roughly 55–60%. - S1 is the mitral and tricuspid valves closing; S2 is the aortic and pulmonary valves closing. The two valve openings are silent in a healthy heart, which is why only two sounds sit on the phonocardiogram. - About 70–80% of ventricular filling is passive. Blood flows in through the open mitral valve before the atria contract; the atrial kick at the end of diastole adds the last 20–30%. #### The 7 phases of the cardiac cycle on a Wiggers diagram Klabunde's seven-phase division, read left to right from the P wave. The valve columns are for the left heart; the tricuspid and pulmonary valves move at nearly the same moments on the right. - 1 Atrial systole — Mitral and aortic valves: Mitral open, aortic closed | What the traces do: Follows the P wave; the a wave on atrial pressure; ventricular volume tops up to about 130 mL - 2 Isovolumetric contraction — Mitral and aortic valves: Both closed | What the traces do: Starts after the QRS with S1; ventricular pressure shoots up while volume stays flat; the c wave - 3 Rapid ejection — Mitral and aortic valves: Mitral closed, aortic open | What the traces do: Ventricular and aortic pressure climb together to about 120 mmHg; volume falls steeply - 4 Reduced ejection — Mitral and aortic valves: Mitral closed, aortic open | What the traces do: Pressures begin to fall; volume falls more slowly toward about 50 mL; the T wave appears - 5 Isovolumetric relaxation — Mitral and aortic valves: Both closed | What the traces do: Starts at S2 and the dicrotic notch; ventricular pressure drops steeply at a flat, low volume; the v wave peaks - 6 Rapid filling — Mitral and aortic valves: Mitral open, aortic closed | What the traces do: Ventricular pressure falls below atrial pressure; volume rises quickly; S3 here if present - 7 Reduced filling (diastasis) — Mitral and aortic valves: Mitral open, aortic closed | What the traces do: Pressures and volume level off and aortic pressure keeps sinking toward 80 mmHg until the next P wave Courses do not all count seven. A four-phase scheme keeps ventricular filling, isovolumetric contraction, ejection and isovolumetric relaxation; others merge rapid and reduced ejection, or call phase 7 diastasis. At 75 beats per minute diastasis is the longest phase and the first to disappear as the heart rate climbs. Name the scheme your course uses and the figure is labeled to match. #### Wiggers diagram vs pressure–volume loop A Wiggers diagram plots pressure, volume, the ECG and heart sounds against time; a pressure–volume loop plots left ventricular pressure against left ventricular volume, so time disappears and one beat becomes a closed loop. Both carry the same four valve events: on the Wiggers diagram they are vertical lines where traces cross, on the loop they are its four corners. - Horizontal axis — Wiggers diagram: Time, about 0.8 s for one beat | Pressure–volume loop: Left ventricular volume, about 50 to 130 mL - Vertical axis — Wiggers diagram: Pressure (mmHg), plus volume, ECG and sound panels | Pressure–volume loop: Left ventricular pressure (mmHg) - Valve events — Wiggers diagram: Dashed lines where the pressure traces cross | Pressure–volume loop: The four corners of the loop - Stroke volume — Wiggers diagram: Drop on the volume trace from EDV to ESV | Pressure–volume loop: Width of the loop - Phase durations — Wiggers diagram: Read straight off the time axis | Pressure–volume loop: Not shown; the loop has no time scale - Typical use — Wiggers diagram: Teaching timing, valve sounds and the ECG | Pressure–volume loop: Contractility, preload, afterload and stroke work To turn one into the other, read pressure and volume off the Wiggers diagram at the same instant and plot each pair as a point. The vertical edges of the loop are the two isovolumetric phases, its bottom edge is filling and its rounded top is ejection. #### Who draws Wiggers diagrams The Wiggers diagram is taught in first-year medical physiology, A&P and nursing courses, and it comes back in cardiology wherever a murmur or a catheter tracing has to be explained. The labels change with the level: pressures and volume for a first course, waves, valve events and seven phases for medical school. - Medical and A&P lectures: The figure that ties the ECG, the heart sounds and the pressures together on one slide, used again for exam questions that ask which phase a point belongs to. - Board and exam revision: Study sheets that put each valve event, wave and heart sound in its place, and the valve-disease versions examiners like to compare with the normal trace. - Cardiology and nursing teaching: Explaining a catheter pressure tracing, a pulmonary capillary wedge pressure or the timing of a murmur against S1 and S2. - Papers and theses: Schematic panels that place a measured trace, a device's timing or a model's output against the textbook cycle. #### Questions about the Wiggers diagram **How do you read a Wiggers diagram?** Read it as vertical slices: pick one moment on the time axis and look straight down through every panel. At that instant the pressure panel tells you which chamber pushes harder and so which valves are open, the volume panel whether the ventricle is filling, ejecting or neither, the ECG which electrical event has just happened, and the sound strip whether a valve has just closed. Start at the P wave on the left and move right through the seven phases. **What are the 7 phases of the cardiac cycle?** Atrial systole, isovolumetric contraction, rapid ejection, reduced ejection, isovolumetric relaxation, rapid filling and reduced filling (diastasis). Phases 2 to 4 are ventricular systole and phases 5 to 7 plus phase 1 are ventricular diastole. On a Wiggers diagram each phase is bounded by a valve event or by a change in the slope of the volume trace. **What are the 4 phases of the cardiac cycle?** Ventricular filling, isovolumetric contraction, ventricular ejection and isovolumetric relaxation — the seven-phase scheme with atrial systole, rapid filling and diastasis merged into filling, and the two ejection phases merged into one. The four boundaries are the four valve events, so this is also the scheme that maps onto the corners of a pressure–volume loop. **Is a cardiac cycle diagram the same as a Wiggers diagram?** Often, but not always. In physiology and medicine "cardiac cycle diagram" usually means the Wiggers diagram, the stacked pressure, volume, ECG and sound traces. In school biology it can also mean a sequence of heart cutaways showing which chambers contract and which valves are open. The tool draws either; say traces or hearts. **What causes the dicrotic notch?** The aortic valve closing. As the ventricle relaxes, its pressure drops below aortic pressure, blood briefly flows back toward the heart and snaps the valve shut; the recoil makes a small dip, then a bump, on the aortic trace. It marks the end of ejection, lines up with S2 and starts isovolumetric relaxation. **What are the a, c and v waves on the atrial pressure trace?** The a wave is atrial contraction, the c wave is the mitral valve bulging back into the atrium as the ventricle starts to contract, and the v wave is the atrium filling from the pulmonary veins against a closed mitral valve. The v wave peaks just before the mitral valve opens, after which atrial pressure falls as blood runs into the ventricle. The same three waves appear in the right atrium and the jugular venous pulse. **Why is it called isovolumetric contraction?** Because the ventricle contracts with both of its valves closed, so its volume cannot change. The mitral valve has just shut and the aortic valve has not yet opened; pressure climbs from about 10 to about 80 mmHg in roughly 50 ms while the volume trace stays flat at the end-diastolic volume. Isovolumetric relaxation is the same flat stretch in reverse, after the aortic valve closes. **Where do S1 and S2 fall on the Wiggers diagram?** S1 at the start of isovolumetric contraction, when the mitral and tricuspid valves close, just after the QRS complex; S2 at the dicrotic notch, when the aortic and pulmonary valves close, just after the T wave. The interval from S1 to S2 is ventricular systole; from S2 to the next S1 is diastole, which is the longer of the two at normal heart rates. **How does the ECG line up with the cardiac cycle?** Each ECG wave comes just before the mechanical event it triggers. The P wave (atrial depolarization) precedes atrial systole, the QRS complex (ventricular depolarization) precedes the rise in ventricular pressure, and the T wave (ventricular repolarization) comes before the ventricles relax and the aortic valve closes. **How do you find stroke volume, ejection fraction and heart rate on a Wiggers diagram?** Stroke volume is end-diastolic minus end-systolic volume on the volume trace, for example 130 − 60 = 70 mL; ejection fraction is stroke volume divided by end-diastolic volume, here about 54%; heart rate is 60 divided by the length of one cycle in seconds, so 0.8 s gives 75 beats per minute. Multiply stroke volume by heart rate for cardiac output, about 5.25 L/min in this example. **How does aortic stenosis change the Wiggers diagram?** The left ventricular trace climbs far above the aortic trace during ejection, and the gap between them is the valve gradient. The aortic trace itself rises slowly and peaks late, the ejection phase lengthens, and a crescendo–decrescendo systolic murmur appears on the sound strip between S1 and S2. #### Sources - 19.3 Cardiac Cycle, in OpenStax Anatomy and Physiology 2e — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/19-3-cardiac-cycle - Cardiac Cycle — Cardiovascular Physiology Concepts — Richard E. Klabunde: https://cvphysiology.com/heart-disease/hd002 --- ### Brachial Plexus Diagram: Labeled Anatomy and Mnemonic URL: https://scientificfigure.com/tools/brachial-plexus-diagram Description: Labeled brachial plexus diagram: roots C5–T1, trunks, divisions, cords and five terminal branches, with the Randy Travis mnemonic, Erb's palsy and block sites. #### What is the brachial plexus? The brachial plexus is the network of nerves formed by the anterior rami of spinal nerves C5, C6, C7, C8 and T1 that supplies almost all the muscles and skin of the upper limb. It runs from the side of the neck, between the scalene muscles, over the first rib and behind the clavicle into the axilla, regrouping on the way from five roots into three trunks, six divisions, three cords and five terminal nerves. A brachial plexus diagram lays those five stages out left to right so each nerve can be traced back to its roots. The figures here are for anatomy teaching and revision, not for planning a procedure. - 5 roots, 3 trunks, 6 divisions, 3 cords, 5 terminal branches. Randy Travis Drinks Cold Beer gives the order; the counts are what an exam sketch is marked on. - The divisions are the only stage with no branches of their own. Every collateral comes off a root, the upper trunk or a cord. - The posterior cord is the only cord built from all three trunks, which is why it carries C5 to T1 and why the radial nerve has every root value of the plexus. - The median nerve has two roots, one from the lateral cord and one from the medial cord, and the V they make in front of the axillary artery is the centre of the M seen in dissection. - The cords are named for their position around the second part of the axillary artery, behind pectoralis minor, not for their position on a schematic. #### Parts of the brachial plexus and what each supplies Every labeled part of the ladder, read from the spine outward: where it arises, its root values and what it supplies. - Roots — Arises from: Anterior rami of the spinal nerves | Roots: C5, C6, C7, C8, T1 | Supplies: Pass between the anterior and middle scalenes to form the trunks - Dorsal scapular nerve — Arises from: C5 root | Roots: C5 | Supplies: Rhomboid major and minor, part of levator scapulae - Long thoracic nerve — Arises from: C5, C6 and C7 roots | Roots: C5–C7 | Supplies: Serratus anterior - Upper trunk — Arises from: C5 and C6 roots | Roots: C5–C6 | Supplies: Anterior and posterior divisions; suprascapular nerve and nerve to subclavius - Middle trunk — Arises from: C7 root alone | Roots: C7 | Supplies: Anterior and posterior divisions; no branches - Lower trunk — Arises from: C8 and T1 roots | Roots: C8–T1 | Supplies: Anterior and posterior divisions; no branches - Suprascapular nerve — Arises from: Upper trunk | Roots: C5–C6 | Supplies: Supraspinatus, infraspinatus, shoulder joint - Nerve to subclavius — Arises from: Upper trunk | Roots: C5–C6 | Supplies: Subclavius - Anterior divisions — Arises from: Front of each trunk | Roots: C5–T1 | Supplies: Lateral and medial cords, the flexor side of the limb - Posterior divisions — Arises from: Back of each trunk | Roots: C5–T1 | Supplies: Posterior cord, the extensor side of the limb - Lateral cord — Arises from: Anterior divisions of upper and middle trunks | Roots: C5–C7 | Supplies: Lateral pectoral, musculocutaneous, lateral root of median - Posterior cord — Arises from: Posterior divisions of all three trunks | Roots: C5–T1 | Supplies: Subscapular and thoracodorsal nerves, axillary, radial - Medial cord — Arises from: Anterior division of lower trunk | Roots: C8–T1 | Supplies: Medial pectoral, medial cutaneous nerves, medial root of median, ulnar - Lateral pectoral nerve — Arises from: Lateral cord | Roots: C5–C7 | Supplies: Pectoralis major - Upper subscapular nerve — Arises from: Posterior cord | Roots: C5–C6 | Supplies: Upper part of subscapularis - Thoracodorsal nerve — Arises from: Posterior cord | Roots: C6–C8 | Supplies: Latissimus dorsi - Lower subscapular nerve — Arises from: Posterior cord | Roots: C5–C6 | Supplies: Lower part of subscapularis, teres major - Medial pectoral nerve — Arises from: Medial cord | Roots: C8–T1 | Supplies: Pectoralis minor and part of pectoralis major - Medial cutaneous nerve of arm — Arises from: Medial cord | Roots: C8–T1 | Supplies: Skin of the medial arm - Medial cutaneous nerve of forearm — Arises from: Medial cord | Roots: C8–T1 | Supplies: Skin of the medial forearm - Musculocutaneous nerve — Arises from: Lateral cord | Roots: C5–C7 | Supplies: Coracobrachialis, biceps, brachialis; skin of the lateral forearm - Axillary nerve — Arises from: Posterior cord | Roots: C5–C6 | Supplies: Deltoid, teres minor; skin over the lower deltoid - Radial nerve — Arises from: Posterior cord | Roots: C5–T1 | Supplies: Triceps, the extensors of the forearm; skin of the back of arm, forearm and hand - Median nerve — Arises from: Lateral and medial cords | Roots: C6–T1 (C5) | Supplies: Most forearm flexors, thenar muscles, lateral two lumbricals; palmar skin of the lateral three and a half fingers - Ulnar nerve — Arises from: Medial cord | Roots: C8–T1 | Supplies: Flexor carpi ulnaris, medial half of flexor digitorum profundus, most hand muscles; skin of the medial one and a half fingers Root values follow TeachMeAnatomy and Kenhub; textbooks differ by one level for a few nerves, most often the ulnar (some add C7) and the median (some add C5). The spinal levels on an exam answer should match the textbook the course uses. #### Erb's palsy vs Klumpke's palsy Erb's palsy is an upper plexus injury of C5 and C6 that weakens the shoulder and elbow; Klumpke's palsy is a lower plexus injury of C8 and T1 that weakens the hand. On a brachial plexus diagram the difference is which end of the ladder is shaded: the upper trunk or the lower trunk. - Roots — Erb's palsy (upper): C5, C6 (sometimes C7) | Klumpke's palsy (lower): C8, T1 - Part of the plexus — Erb's palsy (upper): Upper trunk | Klumpke's palsy (lower): Lower trunk - How it happens — Erb's palsy (upper): Head and shoulder forced apart: shoulder dystocia at birth, a fall or a motorbike crash onto the shoulder | Klumpke's palsy (lower): Arm pulled up above the head: a breech delivery, grabbing a branch while falling - Nerves hit hardest — Erb's palsy (upper): Suprascapular, musculocutaneous, axillary, nerve to subclavius | Klumpke's palsy (lower): Ulnar and the medial root of the median - Muscles weak — Erb's palsy (upper): Deltoid, supraspinatus, infraspinatus, biceps, brachialis | Klumpke's palsy (lower): Intrinsic muscles of the hand - Classic sign — Erb's palsy (upper): Waiter's tip: arm adducted and medially rotated, elbow extended, forearm pronated | Klumpke's palsy (lower): Claw hand: fingers extended at the knuckles and flexed at the finger joints - Numb skin — Erb's palsy (upper): Outer shoulder and lateral arm (C5–C6 dermatomes) | Klumpke's palsy (lower): Medial forearm and hand (C8–T1 dermatomes) - How common — Erb's palsy (upper): The commoner of the two | Klumpke's palsy (lower): Much rarer; Horner's syndrome if T1 is torn near the spinal cord Most birth injuries are upper or upper-and-middle (C5–C7); a pure lower lesion is uncommon, and a total plexus injury takes all five roots. When shading a diagram, mark the roots and the trunk together, then trace which terminal nerves leave the shaded part. #### Who draws the brachial plexus Medical and anatomy students draw it most, for upper limb exams and dissection, followed by trainees in anaesthesia, physiotherapy and paediatrics. These figures support study and teaching and are not a guide to placing a needle. - Anatomy exams: The ladder from memory with the collaterals and root values, the classic short-answer question in upper limb anatomy. - Regional anaesthesia teaching: Interscalene, supraclavicular, infraclavicular and axillary levels marked on the plexus for block teaching slides. - Physiotherapy and hand therapy: Which root and which cord a weak muscle points to, and where nerve glide exercises put tension on the plexus. - Obstetrics and neonatal care: Birth-related brachial plexus palsy explained to students and families: which roots, which nerves and what recovery looks like. #### Brachial plexus questions **Where is the brachial plexus located?** At the side of the neck and in the armpit. Its roots come out between the anterior and middle scalene muscles, its trunks cross the base of the posterior triangle of the neck above the first rib, its divisions pass behind the clavicle, and its cords and branches lie in the axilla around the axillary artery before running down the arm. **What are the roots of the brachial plexus?** The anterior rami of the spinal nerves C5, C6, C7, C8 and T1. The posterior rami of the same nerves go to the back muscles and skin, not into the plexus. A small contribution from C4 makes a prefixed plexus, one from T2 a postfixed plexus. **What are the five terminal branches of the brachial plexus?** The musculocutaneous, axillary, radial, median and ulnar nerves. The musculocutaneous comes off the lateral cord, the axillary and radial off the posterior cord, the ulnar off the medial cord, and the median is formed from both the lateral and the medial cords. **What is the mnemonic for the brachial plexus?** Randy Travis Drinks Cold Beer: roots, trunks, divisions, cords, branches. For the terminal nerves in order on the schematic, MARMU (musculocutaneous, axillary, radial, median, ulnar); for the posterior cord, ULTRA (upper subscapular, lower subscapular, thoracodorsal, radial, axillary). **Which cord does the axillary nerve come from?** The posterior cord, with root values C5 and C6. It leaves the axilla through the quadrangular space with the posterior circumflex humeral artery, winds round the surgical neck of the humerus, and supplies the deltoid and teres minor and the skin over the lower deltoid. **Which nerve damage causes a winged scapula?** Usually the long thoracic nerve (C5, C6, C7), which supplies serratus anterior. It comes straight off the roots and runs down the outside of the chest wall, where it is exposed in surgery and to strain; with serratus anterior weak, the medial border of the scapula lifts off the ribs when pushing against a wall. **What does the dorsal scapular nerve supply?** The rhomboid major, rhomboid minor and part of levator scapulae. It is the first branch of the plexus, coming off the C5 root alone and piercing the middle scalene, which is why it sits at the top left of a fully labeled schematic. **What does the thoracodorsal nerve supply?** Latissimus dorsi. It comes off the posterior cord (C6–C8) between the upper and lower subscapular nerves and runs down the posterior wall of the axilla to the muscle; surgeons reuse it as a donor nerve in plexus repair. **Why does an interscalene block miss the ulnar nerve?** Because the injection is made around the C5 to C7 roots and upper trunks, and the local anaesthetic often fails to reach C8 and T1, the roots of the ulnar nerve. It suits shoulder surgery, and it nearly always blocks the phrenic nerve on that side too, which lies on anterior scalene close by. **What is the M in the brachial plexus?** The letter formed by the musculocutaneous, median and ulnar nerves in front of the axillary artery. The lateral cord gives the musculocutaneous nerve and the lateral root of the median, the medial cord gives the medial root and the ulnar nerve, and the two roots meeting make the middle of the M. It is the landmark used to orient a dissection. #### Sources - The Brachial Plexus — TeachMeAnatomy: https://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/ - Brachial plexus: Anatomy, branches and mnemonics — Kenhub: https://www.kenhub.com/en/library/anatomy/brachial-plexus --- ### Krebs Cycle Diagram — Labeled Citric Acid Cycle Maker URL: https://scientificfigure.com/tools/krebs-cycle-diagram Description: Draw a labeled Krebs cycle (citric acid, TCA) diagram: 8 steps, intermediates, enzymes and the 2 CO₂, 3 NADH, 1 FADH₂ and 1 GTP per turn, simple or full. #### What is the Krebs cycle? The Krebs cycle, also called the citric acid cycle or the tricarboxylic acid (TCA) cycle, is the eight-step loop in the mitochondrial matrix that oxidizes the two-carbon acetyl group of acetyl-CoA to two CO₂, stores the energy as 3 NADH, 1 FADH₂ and 1 GTP or ATP per turn, and ends by regenerating the oxaloacetate it started with. A Krebs cycle diagram draws that loop with its intermediates in order and its products leaving at the steps that make them. - It runs in the mitochondrial matrix. All of its enzymes are dissolved in the matrix except succinate dehydrogenase, which sits in the inner membrane; in bacteria the cycle runs in the cytoplasm. - Each turn takes in 2 carbons and gives out 2 CO₂. Acetyl-CoA (2C) joins oxaloacetate (4C) to make citrate (6C); two decarboxylations bring it back to four carbons and the rest of the loop rebuilds oxaloacetate. - Most of the energy leaves as NADH and FADH₂, not ATP. One turn makes 3 NADH, 1 FADH₂ and only 1 GTP or ATP directly; the electron carriers are worth about 9 more ATP once the electron transport chain uses them. - The cycle turns twice for every glucose. Glycolysis splits glucose into two pyruvate, each becomes one acetyl-CoA, so per glucose the cycle gives 4 CO₂, 6 NADH, 2 FADH₂ and 2 GTP or ATP. - It was worked out by Hans Krebs in the 1930s in pigeon flight muscle. The name citric acid cycle comes from its first product, and TCA cycle from citrate and isocitrate being tricarboxylic acids. #### The 8 steps of the Krebs cycle Read clockwise from the top of the loop. The third column is what a labeled diagram puts on the side arrow of each step. - 1 Citrate synthase — Reaction: Acetyl-CoA (2C) + oxaloacetate (4C) → citrate (6C) | What leaves or is made: CoA-SH is released; the step is irreversible - 2 Aconitase — Reaction: Citrate → isocitrate, by way of cis-aconitate | What leaves or is made: Nothing leaves; the hydroxyl group is moved - 3 Isocitrate dehydrogenase — Reaction: Isocitrate (6C) → α-ketoglutarate (5C) | What leaves or is made: CO₂ and the first NADH; the main control point - 4 α-Ketoglutarate dehydrogenase — Reaction: α-Ketoglutarate (5C) → succinyl-CoA (4C) | What leaves or is made: The second CO₂ and the second NADH - 5 Succinyl-CoA synthetase — Reaction: Succinyl-CoA → succinate | What leaves or is made: GTP (or ATP) by substrate-level phosphorylation; CoA-SH released - 6 Succinate dehydrogenase — Reaction: Succinate → fumarate | What leaves or is made: FADH₂; the enzyme is complex II of the electron transport chain - 7 Fumarase — Reaction: Fumarate + H₂O → malate | What leaves or is made: Nothing leaves; water is added - 8 Malate dehydrogenase — Reaction: Malate → oxaloacetate | What leaves or is made: The third NADH; oxaloacetate is ready for the next acetyl-CoA Some textbooks count nine or ten steps. They draw cis-aconitate as its own intermediate, or start with the pyruvate dehydrogenase step that makes acetyl-CoA, which is not part of the cycle itself. Older books call step 5's enzyme succinic thiokinase, and heart and muscle make ATP at that step while liver makes GTP. Say which names and how many steps your course uses. #### Krebs cycle vs Calvin cycle The Krebs cycle takes carbon apart and the Calvin cycle puts it together: the Krebs cycle oxidizes acetyl groups to CO₂ in the mitochondria and fills NAD⁺ and FAD with electrons, while the Calvin cycle fixes CO₂ into sugar in the chloroplast and spends ATP and NADPH to do it. Both are closed loops that rebuild their starting molecule, which is why they are compared. - Where — Krebs cycle: Mitochondrial matrix | Calvin cycle: Chloroplast stroma - Part of — Krebs cycle: Cellular respiration (breaks molecules down) | Calvin cycle: Photosynthesis (builds sugar) - CO₂ — Krebs cycle: Released, 2 per turn | Calvin cycle: Taken in, 1 per turn, by RuBisCO - Electron carriers — Krebs cycle: NAD⁺ and FAD reduced to NADH and FADH₂ | Calvin cycle: NADPH oxidized to NADP⁺ - ATP — Krebs cycle: 1 GTP or ATP made per turn | Calvin cycle: 3 ATP used per CO₂ fixed - Regenerated molecule — Krebs cycle: Oxaloacetate (4C) | Calvin cycle: RuBP (5C) On a diagram, follow the CO₂ arrows: in the Krebs cycle they point out of the loop, in the Calvin cycle into it. Plants run both, the Calvin cycle in chloroplasts by day and the Krebs cycle in mitochondria all the time. #### Who draws Krebs cycle diagrams The Krebs cycle is drawn from high-school biology to medical biochemistry, and the label set grows with the level: intermediates and products first, then enzymes and carbon counts, then structures, regulation and links to other pathways. - School biology: GCSE, A-level, AP and IB respiration topics, where the cycle sits between the link reaction and oxidative phosphorylation. - University biochemistry: Lecture slides and exam revision with every enzyme, cofactor and carbon count, and the yield calculations per glucose. - Medicine and nutrition: Vitamin cofactors (thiamine, riboflavin, niacin, pantothenic acid) placed on the steps that need them, and enzyme defects such as fumarase deficiency. - Research figures: Metabolic schematics for papers on cancer metabolism, isotope tracing or mitochondrial disease, with measured changes marked on the intermediates. #### Questions about the Krebs cycle **Is a Krebs cycle diagram the same as a citric acid cycle diagram?** Yes. Krebs cycle, citric acid cycle and TCA (tricarboxylic acid) cycle are three names for one pathway, so the three diagrams show the same loop. Biology courses tend to say Krebs cycle, biochemistry courses citric acid or TCA cycle. Use whichever name your course uses in the title; the intermediates and products do not change. **Where does the Krebs cycle take place?** In the mitochondrial matrix, the space inside the inner mitochondrial membrane. The one exception is succinate dehydrogenase (step 6), which is anchored in the inner membrane itself. In bacteria, which have no mitochondria, the cycle runs in the cytoplasm. **What are the 8 steps of the Krebs cycle?** 1 acetyl-CoA joins oxaloacetate to make citrate; 2 citrate becomes isocitrate; 3 isocitrate becomes α-ketoglutarate, releasing CO₂ and NADH; 4 α-ketoglutarate becomes succinyl-CoA, releasing CO₂ and NADH; 5 succinyl-CoA becomes succinate, making GTP or ATP; 6 succinate becomes fumarate, making FADH₂; 7 fumarate takes up water to become malate; 8 malate becomes oxaloacetate, making NADH. **What are the reactants and products of the Krebs cycle?** Per turn it takes in 1 acetyl-CoA, 3 NAD⁺, 1 FAD, 1 GDP (or ADP) with phosphate and 2 H₂O, and gives out 2 CO₂, 3 NADH, 1 FADH₂, 1 GTP (or ATP) and CoA. Oxaloacetate is used at step 1 and made again at step 8, so it is neither a reactant nor a product overall. **How many ATP does the Krebs cycle produce?** Directly, one GTP or ATP per turn, so two per glucose. Counting the 3 NADH and 1 FADH₂ at about 2.5 and 1.5 ATP each in the electron transport chain, one turn is worth about 10 ATP, or about 20 per glucose. **Does the Krebs cycle need oxygen?** It uses no oxygen itself, but it stops without it, so it counts as aerobic. The cycle needs a steady supply of NAD⁺ and FAD, and those are only regenerated when the electron transport chain can pass electrons to oxygen. Without oxygen, NADH builds up and the dehydrogenase steps halt. **Why does the Krebs cycle turn twice per glucose?** Because one glucose gives two pyruvate in glycolysis, and each pyruvate becomes one acetyl-CoA. Each acetyl-CoA drives one turn, so per glucose every product doubles: 4 CO₂, 6 NADH, 2 FADH₂ and 2 GTP or ATP. **What happens to pyruvate before the Krebs cycle?** It is carried into the mitochondrial matrix and converted to acetyl-CoA by the pyruvate dehydrogenase complex, releasing one CO₂ and one NADH. This link reaction is not one of the eight steps, but most diagrams draw it as the arrow coming into the top of the loop. **Is there a mnemonic for the Krebs cycle intermediates?** A common one is "Citrate Is Krebs' Starting Substrate For Making Oxaloacetate": citrate, isocitrate, α-ketoglutarate, succinyl-CoA, succinate, fumarate, malate, oxaloacetate. The initials follow the loop clockwise from the top, so it also gives the order for labeling a diagram. **Which enzymes control the Krebs cycle?** Citrate synthase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, the three steps with large energy drops. High ATP and NADH slow them down; calcium speeds both dehydrogenases up and ADP speeds isocitrate dehydrogenase, so the cycle runs faster when a muscle is working. **How is the Krebs cycle different from the electron transport chain?** The Krebs cycle strips electrons from acetyl groups and loads them onto NAD⁺ and FAD; the electron transport chain, in the inner membrane, takes them from NADH and FADH₂, passes them to oxygen and uses the energy to make most of the cell's ATP. They are drawn as separate figures, the cycle in the matrix and the chain across the membrane. #### Sources - 7.3 Oxidation of Pyruvate and the Citric Acid Cycle, in OpenStax Biology 2e — OpenStax: https://openstax.org/books/biology-2e/pages/7-3-oxidation-of-pyruvate-and-the-citric-acid-cycle - 24.2 Carbohydrate Metabolism, in OpenStax Anatomy and Physiology 2e — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/24-2-carbohydrate-metabolism --- ### Carbon Cycle Diagram — Labeled, Simple & Easy to Draw URL: https://scientificfigure.com/tools/carbon-cycle-diagram Description: Make a labeled carbon cycle diagram: photosynthesis, respiration, decomposition, fossil fuels, combustion and ocean exchange, or a simple one to draw by hand. #### What is the carbon cycle? The carbon cycle is the movement of carbon between the atmosphere, living things, soils, the ocean and rocks: plants and algae take carbon dioxide out of the air by photosynthesis, and respiration, decomposition, combustion and volcanoes return it. A carbon cycle diagram draws each store as a box or a scene and each transfer as a one-way arrow, so the carbon can be followed from the air into a leaf and back out again. - CO₂ is only about 0.04% of the air, roughly 420 parts per million. Before the Industrial Revolution it was about 280 ppm; the rise comes from burning fossil fuels and clearing forests. - Most of Earth's carbon is locked in rock. NASA puts it at about 65,500 billion tonnes, mostly as limestone formed from the calcium carbonate shells of marine organisms — the largest carbon reservoir on the planet. - The ocean holds roughly 50 times as much carbon as the atmosphere. More than 90% of it is dissolved as bicarbonate ions, made when CO₂ reacts with seawater. - Photosynthesis and respiration nearly cancel out. Each moves on the order of 120 billion tonnes of carbon a year on land; fossil-fuel burning adds about 10, small by comparison but one-way, so it accumulates in the air. - Carbon moves at two speeds. Through living things it cycles within a lifespan; through rocks, weathering, sediments and volcanoes it takes 100–200 million years. #### Steps of the carbon cycle: each process and where it moves carbon The processes a labeled carbon cycle diagram names on its arrows, in the order most textbooks follow — the biological loop first, then the long-term stores and the ocean. - Photosynthesis — Carbon moves from → to: Atmosphere → plants and algae | What happens: Light energy turns CO₂ and water into glucose, releasing O₂ - Feeding — Carbon moves from → to: Plants → animals | What happens: Herbivores, then carnivores, take in carbon as the plant's sugars, fats and proteins - Cellular respiration — Carbon moves from → to: Plants, animals, microbes → atmosphere | What happens: Glucose is broken down with O₂ for energy, giving off CO₂ and water - Death and waste — Carbon moves from → to: Plants and animals → soil | What happens: Leaf litter, dead bodies and dung become soil organic matter - Decomposition — Carbon moves from → to: Soil → atmosphere | What happens: Bacteria and fungi respire the dead material, releasing CO₂ (and methane where there is no oxygen) - Burial and fossilization — Carbon moves from → to: Dead matter → fossil fuels | What happens: Over millions of years, buried remains under heat and pressure become coal, oil and natural gas - Combustion — Carbon moves from → to: Fossil fuels and wood → atmosphere | What happens: Burning oxidizes stored carbon back to CO₂ in seconds - Dissolving (diffusion) — Carbon moves from → to: Atmosphere → ocean | What happens: CO₂ dissolves at the surface, forming carbonic acid, bicarbonate and carbonate ions - Outgassing — Carbon moves from → to: Ocean → atmosphere | What happens: Warm surface water releases dissolved CO₂ back to the air - Sedimentation — Carbon moves from → to: Ocean → seafloor rock | What happens: Calcium carbonate shells settle and harden into limestone - Volcanic eruption — Carbon moves from → to: Rock → atmosphere | What happens: Subducted carbonate rock melts and its carbon escapes as CO₂ A school carbon cycle usually stops at the first seven rows; earth-science courses add the ocean and rock rows. Weathering of silicate rock, which slowly draws CO₂ out of rainwater over millions of years, belongs on the slow-cycle version. Name the processes your syllabus lists and only those arrows are drawn. #### Carbon cycle vs nitrogen cycle Both are biogeochemical cycles that run through the air, soil and living things, but carbon enters life directly through photosynthesis, while nitrogen has to be fixed by bacteria before any plant can use it. That is why the carbon cycle is drawn around plants and the nitrogen cycle around soil microbes. - Form in the air — Carbon cycle: CO₂, about 0.04% of the atmosphere | Nitrogen cycle: N₂, about 78% of the atmosphere - Way into living things — Carbon cycle: Photosynthesis by plants, algae and cyanobacteria | Nitrogen cycle: Fixation by bacteria, then roots take up ammonium and nitrate - Way back to the air — Carbon cycle: Respiration, decomposition and combustion | Nitrogen cycle: Denitrification by bacteria - Largest store — Carbon cycle: Sedimentary rock such as limestone | Nitrogen cycle: The atmosphere - Main human change — Carbon cycle: Fossil fuels and deforestation add CO₂ | Nitrogen cycle: Fertilizer doubles the nitrogen fixed each year - Effect of the excess — Carbon cycle: Warming and ocean acidification | Nitrogen cycle: Algal blooms and dead zones in water The two cycles meet in every living cell. Proteins and nucleic acids need both elements, so a plant's carbon gain from photosynthesis is limited by how much fixed nitrogen its roots can find — the reason nitrogen fertilizer raises crop growth. #### Who draws carbon cycle diagrams The carbon cycle is taught from primary school to university, and it is the background figure for almost every explanation of climate change. The level decides the arrows: six for a first class, a dozen with GtC values for environmental science. - School science: KS3, GCSE, middle-school and AP Environmental Science lessons on photosynthesis, respiration and fossil fuels, often as a figure students redraw from memory. - Earth and environmental science: University courses that add the ocean pumps, weathering, the slow cycle and reservoir sizes. - Climate explainers: Talks, reports and articles that show where the extra CO₂ comes from and how much the ocean and forests take up. - Research figures: Schematic panels for soil carbon, forestry, blue carbon or carbon-capture papers that place one measured flux in the whole cycle. #### Questions about the carbon cycle **What is the carbon cycle in simple terms?** Carbon goes round and round: plants take carbon dioxide out of the air to grow, animals eat the plants, and everything that breathes, rots or burns puts the carbon back into the air. Some carbon gets stuck for a very long time on the way — as coal, oil and gas underground, or as limestone on the seabed — and comes back only when fuel is burned or rock is melted by a volcano. **How do you draw a carbon cycle?** Draw the stores as boxes first and the arrows last. Put an atmosphere box across the top, plants and animals in the middle row, soil with its decomposers and fossil fuels in the bottom row, and the ocean down one side. Then draw one arrow from the atmosphere down into the plants (photosynthesis) and arrows up to the atmosphere from the plants, the animals and the soil (respiration and decomposition) and from the fossil fuels (combustion). Finish with plants → animals (feeding), plants and animals → soil (death and waste), soil → fossil fuels (fossilization) and the two ocean arrows, in and out. Check that every arrow points the way the carbon goes. **What are the steps of the carbon cycle?** Photosynthesis, feeding, respiration, death and decomposition, burial into fossil fuels, and combustion — in that order, the carbon goes from the air into plants, into animals, back to the air or into the soil, and from buried remains back to the air when fuel is burned. Fuller versions add the ocean (dissolving, outgassing and sedimentation into limestone) and volcanic eruption. **How are the carbon and oxygen cycles connected?** Through the two reactions that run them both: photosynthesis uses CO₂ and releases O₂, and cellular respiration uses O₂ and releases CO₂. Fixing six CO₂ into one glucose frees six O₂; respiring that glucose uses the six O₂ and gives the six CO₂ back. That is why the two are often drawn as one figure, the carbon and oxygen cycle. **How do humans affect the carbon cycle?** Mainly by burning fossil fuels, which moves carbon buried over millions of years into the air within a few centuries, and by clearing forests. Together they add roughly 11 billion tonnes of carbon a year. The ocean and land plants absorb a little over half of it; the rest has raised atmospheric CO₂ from about 280 to over 420 ppm, warming the climate and making seawater more acidic. **How does deforestation affect the carbon cycle?** It adds carbon to the air twice. Burning or rotting the cleared trees releases the carbon stored in their wood, and the land then has fewer plants to pull CO₂ out of the air by photosynthesis. Disturbed soil releases some of its own carbon as well. On a carbon cycle diagram it is drawn as an extra up arrow from the forest and a thinner photosynthesis arrow. **What role does combustion play in the carbon cycle?** Combustion returns carbon to the atmosphere as CO₂ by burning it with oxygen — wood, wildfires, and coal, oil and natural gas. Burning wood returns carbon a tree took up within its lifetime; burning fossil fuels returns carbon that was out of the cycle for millions of years, which is why it raises the amount in the air instead of keeping it level. **What role does photosynthesis play in the carbon cycle?** It is the main way carbon leaves the air and enters living things. Plants on land and phytoplankton in the sea use light energy to turn CO₂ and water into glucose, and every food chain on the diagram starts from that sugar. It is the one big downward arrow from the atmosphere on a land carbon cycle diagram. **What do decomposers do in the carbon cycle?** Bacteria and fungi break down dead plants, dead animals and waste and respire the carbon in them back to the air as CO₂. Without them carbon would pile up in dead material. Where oxygen is short — waterlogged peat, deep mud — decomposition slows, and the carbon can be buried long enough to become coal or oil. **How does the ocean store carbon?** CO₂ dissolves at the surface and reacts with water to form bicarbonate and carbonate ions; phytoplankton take some of it up, and two pumps carry it down. Dead plankton and shells sink as marine snow (the biological pump), and cold water sinking near the poles takes dissolved carbon to the deep sea (the solubility pump). Shells that reach the floor build up as carbonate sediments that become limestone. **Why is the carbon cycle important?** It keeps the amount of CO₂ in the air — and therefore Earth's temperature — fairly steady, and it supplies the carbon every living thing is built from. Carbon dioxide traps heat, so when the cycle is pushed out of balance, as fossil-fuel burning is doing now, the climate warms and the ocean becomes more acidic. **Where is most of Earth's carbon stored?** In rocks, especially limestone and other carbonate sediments. After that come the deep ocean, as dissolved bicarbonate, then soils, fossil fuels, land plants and the atmosphere, which holds the least of the large stores but changes the fastest. #### Sources - 46.3 Biogeochemical Cycles, in OpenStax Biology 2e — OpenStax: https://openstax.org/books/biology-2e/pages/46-3-biogeochemical-cycles - The Carbon Cycle — NASA Earth Observatory — NASA: https://science.nasa.gov/earth/earth-observatory/the-carbon-cycle --- ### Ear Diagram — Labeled & Unlabeled Parts of the Ear URL: https://scientificfigure.com/tools/ear-diagram Description: Labeled ear diagram of the outer, middle and inner ear: pinna, ear canal, eardrum, ossicles, cochlea and semicircular canals, plus an unlabeled copy to label. #### What are the three parts of the ear? The ear has three parts: the outer ear (pinna, ear canal and eardrum) collects sound, the middle ear (the malleus, incus and stapes in an air-filled cavity) passes it on, and the inner ear (the cochlea, vestibule and semicircular canals) turns it into nerve signals and senses balance. An ear diagram is usually a coronal section through all three, so the path from the pinna to the vestibulocochlear nerve can be followed in one picture. The figures on this page are drawn for teaching and study, not for clinical use. - The stapes is the smallest bone in the human body, about 3 mm long. With the malleus and incus it carries vibration from the eardrum to the oval window. - The middle ear raises the pressure of sound about 20 times. The eardrum is roughly 17 times larger than the stapes footplate, and the lever action of the ossicles adds a little more — enough to move fluid instead of air. - Humans hear about 20 to 20,000 Hz. The basilar membrane sorts pitch by place: high frequencies move it near the base of the cochlea, low frequencies near the tip. - The cochlea is about two and a half turns, roughly 35 mm long if uncoiled. Its organ of Corti holds about 3,500 inner and 12,000 outer hair cells. - Half of the inner ear is for balance, not hearing. The utricle and saccule sense tilt and straight-line acceleration; the three semicircular canals sense rotation. #### Parts of the ear and their functions Each part on the labeled ear diagram, the region it belongs to and what it does, from the outside in. - Pinna (auricle) — Region: Outer ear | What it does: Elastic-cartilage flap that gathers sound and helps tell whether it comes from in front or behind - External auditory canal — Region: Outer ear | What it does: Carries sound about 2.5 cm to the eardrum; its glands make earwax - Tympanic membrane (eardrum) — Region: Outer–middle border | What it does: Thin membrane that vibrates with sound and moves the malleus - Malleus (hammer) — Region: Middle ear | What it does: First ossicle; its handle is attached to the eardrum - Incus (anvil) — Region: Middle ear | What it does: Middle ossicle, linking the malleus to the stapes - Stapes (stirrup) — Region: Middle ear | What it does: Last ossicle; its footplate rocks in the oval window and pushes on the cochlear fluid - Oval window — Region: Middle–inner border | What it does: Membrane-covered opening where vibration enters the cochlea - Round window — Region: Middle–inner border | What it does: Bulges out to relieve the pressure wave once it has run through the cochlea - Eustachian tube — Region: Middle ear to nasopharynx | What it does: Lets air in and out to keep pressure equal on both sides of the eardrum; drains the middle ear - Cochlea — Region: Inner ear | What it does: Coiled, fluid-filled tube whose hair cells turn vibration into nerve signals for hearing - Vestibule — Region: Inner ear | What it does: Holds the utricle and saccule, which sense head tilt and straight-line acceleration - Semicircular canals — Region: Inner ear | What it does: Three fluid-filled loops at right angles that sense head rotation - Vestibulocochlear nerve (CN VIII) — Region: Inner ear to brainstem | What it does: Carries hearing signals from the cochlea and balance signals from the vestibule and canals - Temporal bone — Region: Around all three | What it does: The skull bone that houses the ear canal, middle ear and inner ear School sheets often merge the three ossicles into one "ear bones" label and call the vestibulocochlear nerve the auditory nerve. Anatomy courses keep them apart and add the vestibule and both windows. Say which set your class uses and only those labels are drawn. #### Outer ear vs middle ear vs inner ear The outer ear carries sound through air, the middle ear carries it through bone, and the inner ear carries it through fluid and turns it into nerve signals. Each region ends at a membrane: the eardrum closes the outer ear, the oval and round windows close the middle ear. - Parts — Outer ear: Pinna, ear canal, outer face of the eardrum | Middle ear: Malleus, incus, stapes, tympanic cavity, Eustachian tube | Inner ear: Cochlea, vestibule, semicircular canals - Filled with — Outer ear: Air, open to the outside | Middle ear: Air, vented through the Eustachian tube | Inner ear: Fluid: perilymph and endolymph - Sound travels as — Outer ear: Pressure waves in air | Middle ear: Vibration of three bones | Inner ear: Fluid waves, then nerve impulses - Job — Outer ear: Collect and channel sound | Middle ear: Amplify and pass it on | Inner ear: Detect pitch and loudness; sense balance - Hearing loss if it fails — Outer ear: Conductive | Middle ear: Conductive | Inner ear: Sensorineural On a diagram, the eardrum is the line between the outer and middle ear and the stapes footplate in the oval window is the line between the middle and inner ear. Brackets that put the eardrum inside the middle ear, or the cochlea beside the ossicles, are the first things to check. #### Who uses ear diagrams Ear diagrams are drawn mainly for teaching — school biology, psychology and A&P courses — and for study materials in audiology, nursing and speech science. These figures are for teaching and study; they are not a substitute for a clinician's examination. - School biology and psychology: Labeling sheets on the sense organs for middle school, GCSE, AP Biology and AP Psychology's sensation unit. - Anatomy and physiology courses: Lab practicals and lecture slides on the special senses, with the windows, vestibule and cranial nerve VIII. - Audiology and speech science: Study figures for the hearing pathway, the cochlea's place coding and where conductive and sensorineural losses arise. - Health education: Plain illustrations for leaflets on hearing protection, earwax or ear infections, marked as teaching figures. #### Questions about the ear diagram **What are the parts of the ear?** The outer ear (pinna, ear canal), the eardrum, the middle ear (malleus, incus, stapes and the Eustachian tube) and the inner ear (cochlea, vestibule and semicircular canals), with the vestibulocochlear nerve leading to the brain. A labeled ear diagram for an anatomy course also names the oval and round windows and the temporal bone around them. **What are the parts of the outer ear called?** The pinna (auricle) and the external auditory canal; on the pinna itself, the helix, antihelix, concha, tragus, antitragus, the scaphoid and triangular fossae and the lobule. The eardrum sits at the inner end of the canal and is usually counted as the boundary with the middle ear. **What are the three bones in the ear called?** The malleus (hammer), incus (anvil) and stapes (stirrup), in that order from the eardrum inward. Together they are the auditory ossicles. The malleus is attached to the eardrum, the incus joins it to the stapes, and the stapes footplate fits into the oval window of the cochlea. **Is the eardrum part of the outer or middle ear?** It is the wall between them. Its outer surface faces the ear canal and its inner surface faces the middle-ear cavity, with the malleus handle attached; most diagrams draw the outer-ear bracket ending at the eardrum and the middle-ear bracket starting just behind it. **Which part of the ear controls balance?** The vestibular system of the inner ear: the three semicircular canals, which sense rotation of the head, and the utricle and saccule in the vestibule, which sense tilt and straight-line movement. Their signals travel on the vestibular branch of the vestibulocochlear nerve, alongside the hearing signals from the cochlea. **What does the cochlea do?** It turns sound vibrations into nerve signals. The stapes pushes a wave through the fluid in the coiled cochlea; the wave bends the hair cells of the organ of Corti on the basilar membrane, and they fire the cochlear nerve. Where along the coil the wave peaks tells the brain the pitch: high notes near the base, low notes near the tip. **What does the Eustachian tube do?** It connects the middle ear to the nasopharynx at the back of the nose, so air can enter or leave and the pressure stays equal on both sides of the eardrum. Swallowing or yawning opens it, which is the pop felt on a plane. It also drains the middle ear; in young children it is shorter and more level. **How does sound travel through the ear?** Pinna → ear canal → eardrum → malleus → incus → stapes → oval window → fluid in the cochlea → hair cells → cochlear nerve → brain. It goes as air pressure waves in the outer ear, bone vibration in the middle ear and fluid waves in the inner ear, and leaves as electrical signals. **What should a labeled ear diagram include?** At minimum the pinna, ear canal, eardrum, the three ossicles, the cochlea, the semicircular canals, the Eustachian tube and the auditory nerve. Fuller answer keys add the oval and round windows, the vestibule and the temporal bone, with brackets for the outer, middle and inner ear. **What is the smallest bone in the human body?** The stapes, in the middle ear — about 3 mm long and weighing a few milligrams. Its two arms and oval footplate give it the stirrup shape behind its common name; the footplate is the only part of the ossicle chain that touches the inner ear. #### Sources - 14.1 Sensory Perception (Audition and Equilibrium), in OpenStax Anatomy and Physiology 2e — OpenStax: https://openstax.org/books/anatomy-and-physiology-2e/pages/14-1-sensory-perception - How Do We Hear? — National Institute on Deafness and Other Communication Disorders (NIDCD): https://www.nidcd.nih.gov/health/how-do-we-hear --- ### Dermatome Map and Dermatome Chart, C2 to S5 Labeled URL: https://scientificfigure.com/tools/dermatome-map Description: Labeled dermatome map of the front and back of the body, a dermatome chart with the sensory exam landmarks, and arm and leg dermatomes from C5 to S2. #### What is a dermatome? A dermatome is the strip of skin whose sensation is carried by the sensory root of one spinal nerve, and a dermatome map draws those strips on the body, from C2 at the back of the head to S5 around the anus. Each strip feeds one dorsal root ganglion, so numbness, pain or a rash confined to one band points to one spinal level. There are about 30 on each side; C1 usually has none, and the face is supplied by the trigeminal nerve instead. The figures on this page follow the Keegan and Garrett map of 1948, the one most textbooks print, and are meant for teaching and study; they are no basis for a clinical decision. - Three trunk landmarks carry most exam questions: T4 at the nipple line, T6 at the xiphoid process and T10 at the umbilicus. - Three digits of the hand split C6, C7 and C8: the thumb is C6, the middle finger C7 and the little finger C8. - L4 is the inner shin and medial malleolus, L5 the top of the foot and big toe, S1 the heel and outer foot, the three levels a lumbar disc most often affects. - Adjacent dermatomes overlap, so cutting a single root usually leaves only a narrow zone of reduced feeling rather than a whole numb band. - Shingles follows one dermatome on one side of the body, because the virus reactivates in a single dorsal root ganglion or in the trigeminal ganglion. #### Dermatome chart: spinal level to landmark Each level on the map, the landmark it is tested at and the skin it covers, from the head down. The landmarks are the key sensory points used in a neurological sensory exam. - C2 — Landmark: Occiput | Skin it covers: Back of the scalp and the angle of the jaw - C3 — Landmark: Neck | Skin it covers: Front and back of the neck, in the supraclavicular fossa - C4 — Landmark: Top of the shoulder | Skin it covers: Shoulders and collarbones, over the acromioclavicular joint - C5 — Landmark: Lateral upper arm | Skin it covers: Outer arm over the deltoid, down to the lateral side of the elbow - C6 — Landmark: Thumb | Skin it covers: Thumb side of the forearm, the thumb and part of the index finger - C7 — Landmark: Middle finger | Skin it covers: Middle finger and the middle of the hand, front and back - C8 — Landmark: Little finger | Skin it covers: Ring and little fingers and the ulnar edge of the hand - T1 — Landmark: Medial forearm | Skin it covers: Inner forearm up to the elbow - T2 — Landmark: Apex of the axilla | Skin it covers: Inner upper arm, armpit and the top of the chest - T4 — Landmark: Nipple line | Skin it covers: Chest band at the fourth intercostal space - T6 — Landmark: Xiphoid | Skin it covers: Band at the lower end of the sternum - T10 — Landmark: Umbilicus | Skin it covers: Band through the navel - T12 / L1 — Landmark: Inguinal region | Skin it covers: T12 just above the inguinal ligament, L1 the groin below it - L2 — Landmark: Anterior thigh | Skin it covers: Upper front of the thigh - L3 — Landmark: Knee | Skin it covers: Lower thigh and the inner knee, at the medial femoral condyle - L4 — Landmark: Medial malleolus | Skin it covers: Inner shin down to the inner ankle and the inner edge of the foot - L5 — Landmark: Dorsum of the foot / big toe | Skin it covers: Outer shin and the top of the foot to the big toe - S1 — Landmark: Lateral foot / heel | Skin it covers: Outer edge of the foot, the little toe, the heel and the back of the calf - S2 — Landmark: Posterior thigh | Skin it covers: Strip down the back of the thigh to the popliteal fossa - S3–S5 — Landmark: Perianal | Skin it covers: S3 the medial buttock, S4 and S5 rings around the anus Textbook maps place the bands slightly differently, and the landmarks are where examiners test because those points vary least between people. A map for a spinal cord injury course follows the ISNCSCI key points; an anatomy lecture usually prints the Keegan and Garrett bands. #### Dermatome vs myotome vs peripheral nerve field A dermatome is skin supplied by one spinal root, a myotome is the muscle supplied by one spinal root, and a peripheral nerve field is skin supplied by one named nerve that may carry several roots. The three maps look alike on the arm and leg but answer different questions. - Supplied by — Dermatome: One spinal nerve root | Myotome: One spinal nerve root | Peripheral nerve field: One named nerve, often from several roots - Tested with — Dermatome: Light touch and pinprick on the skin | Myotome: Strength of one key movement | Peripheral nerve field: Touch over the nerve's own patch of skin - Example at C6 — Dermatome: Thumb and the radial forearm | Myotome: Wrist extension | Peripheral nerve field: The thumb is shared by the median and radial nerves - Example at L5 — Dermatome: Top of the foot and big toe | Myotome: Big toe extension | Peripheral nerve field: Top of the foot: superficial and deep fibular nerves - Points to — Dermatome: A root or segment level, such as a disc or shingles | Myotome: A root or segment level | Peripheral nerve field: A nerve injury below the plexus A patch of numbness that crosses a dermatome border but fits one nerve's field points to that nerve, not to the spine. Carpal tunnel syndrome, for example, follows the median nerve across C6, C7 and part of C8. #### Dermatome maps in anatomy, therapy and exam revision Dermatome maps are drawn for anatomy and neuroscience teaching, for physiotherapy, nursing and medical students learning the sensory exam, and for patient leaflets on shingles or sciatica. The figures made here are teaching and study material; a level is assigned to a patient by a clinician's examination, not by matching a picture. - Anatomy and neuroscience courses: Lecture slides and lab sheets on the spinal nerves, with the cervical, thoracic, lumbar and sacral bands in their textbook colours. - Physiotherapy and chiropractic study: Limb maps for the sensory part of a neurological screen, paired with the myotome actions for each level. - Medical and nursing exam revision: The landmark chart behind questions on T4, T10, C6 or L5, and the ISNCSCI points used to score a spinal cord injury. - Patient education: Plain figures for leaflets explaining why a shingles rash or sciatic pain follows one strip of skin, marked as teaching figures. #### Dermatome questions **How many dermatomes are there?** About 30 on each side of the body: C2 to C8 (seven, because C1 usually has no sensory root), T1 to T12, L1 to L5, S1 to S5 and, in some maps, a small coccygeal one. The face is not counted, since the trigeminal nerve supplies it. **What is the C6 dermatome?** The thumb side of the forearm, the thumb and part of the index finger. It is tested on the back of the thumb. A C5 to C6 or C6 to C7 disc can affect it, giving numbness or tingling in the thumb, and the matching myotome is wrist extension. **What do the C5 and C7 dermatomes cover?** C5 is the outer upper arm over the deltoid, down to the lateral elbow; C7 is the middle finger and the middle of the hand. C7 is the commonest cervical root affected by a disc, so the middle finger is the first place to check in a neck-and-arm pain figure. **Where is the L4 dermatome?** Down the inner side of the shin to the medial malleolus and the inner edge of the foot. Its test point is the medial malleolus, and the matching myotome is ankle dorsiflexion. L3, just above it, covers the lower thigh and the inner knee. **What does the S1 dermatome cover?** The outer edge of the foot, the little toe, the heel and part of the back of the calf. It is tested on the lateral heel. An L5 to S1 disc pressing on the S1 root typically gives pain down the back of the leg into the outer foot, with a weak ankle jerk. **Does shingles follow a dermatome?** Yes. The rash covers one dermatome, or two neighbouring ones, on one side of the body and stops at the midline. The virus lies dormant in a dorsal root ganglion or the trigeminal ganglion after chickenpox and travels out along that one nerve when it reactivates. Thoracic bands and the ophthalmic (V1) area of the face are the commonest sites. **What is a dermatomal pattern?** A symptom confined to the territory of one or a few spinal roots, such as pain, numbness or a rash in a single band. A dermatomal pattern suggests a problem at the root, as in a disc prolapse or shingles; a patch that follows one peripheral nerve or covers a whole hand like a glove suggests something else. **Which dermatome is at the umbilicus?** T10. The other trunk landmarks are T4 at the nipple line, T6 at the xiphoid process and T12 just above the inguinal ligament, with L1 in the groin below it. **What is the difference between a dermatome and a myotome?** A dermatome is the skin supplied by one spinal root and is tested by touch and pinprick; a myotome is the muscle supplied by the same root and is tested by strength. C5, for example, is the outer upper arm on the dermatome map and elbow flexion on the myotome chart. **Which dermatome map is correct?** None is exact for every person. The Keegan and Garrett map most textbooks print, Foerster's older map and the Lee 2008 evidence-based map draw some borders in different places, and neighbouring dermatomes overlap. The landmark points are the most reliable part. The figures on this page are for teaching and study and should not be used to make clinical decisions. #### Sources - Dermatomes: What They Are & Locations — Cleveland Clinic: https://my.clevelandclinic.org/health/body/24379-dermatomes - Anatomy, Skin, Dermatomes (Whitman PA, Launico MV, Adigun OO), in StatPearls — StatPearls Publishing, NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK535401/ --- ## Templates and examples ### Free Graphical Abstract Templates — 6 AI-Filled Layouts URL: https://scientificfigure.com/tools/graphical-abstract-templates Description: Six free graphical abstract templates — process flow, comparison, cycle, timeline and more. AI fills your pick from your abstract or PDF at journal size. #### Frequently asked questions **Is there a free graphical abstract template?** Yes — every template on this page is free to try: pick a layout, paste your abstract, and a complete draft renders on the free tier. What you skip compared with a free .pptx download is the manual part — icon hunting, label writing and ratio setup. **Does Elsevier have an official graphical abstract template?** No. Elsevier publishes a specification — minimum 1328 × 531 pixels at 300 dpi, a 2.5:1 ratio — plus sample abstracts, not a downloadable template. Any layout on this page can be composed at that banner ratio. **What is the difference between a template and an example?** A template is a reusable arrangement you start from — it fixes where the stages, arrows and conclusion sit, and contains none of your content. An example is one paper's finished figure — good for judging quality, full of someone else's science. Study examples to calibrate, then start from a template. **Which layout do journals prefer?** None is mandated. The left-to-right process flow is the most common shape in published Elsevier and Cell Press abstracts, which makes it the safe default — but a comparison trial told as a flow buries its own point. Match the layout to the finding, not to fashion. **Can I use the same template for two different journals?** The layout survives, the canvas doesn't. Restacking a 16:9 comparison into Cell Press's square rearranges both arms, so generate at the ratio of the journal you are actually submitting to — and for a second target, re-generate rather than squeeze. **Can I change the visual style of a template?** Yes — layout and style are independent controls in the maker. Any of the six templates renders as flat vector, gradient or hand-drawn sketch: pick the layout for the reader, the style for the venue — vector for journals, sketch for talks and social feeds. --- ### Scientific Poster Templates — 6 Styles Filled from Your PDF URL: https://scientificfigure.com/tools/scientific-poster-templates Description: Skip the blank PowerPoint: six scientific poster templates the AI fills from your paper PDF. Portrait or landscape at your conference poster size, A0 or 48×36. #### Poster template FAQ **Are these scientific poster templates free?** Browsing is free, and new accounts get free credits at signup — enough for your first posters. Each generation costs 30 credits, and failed generations are refunded automatically. **Can I download these as a PowerPoint file?** No — these are not .pptx templates. The AI renders a finished poster you edit in the workspace and export as an image or PDF for the printer. If a PowerPoint file is what you need, the free template sites above are the right stop. **Do I need PowerPoint or design software?** No — that is the point. Each template already encodes the academic layout, and the AI fills it from your paper. Generate, fine-tune text and colours in the workspace, then export a print-ready file. **Can I make an A0 portrait poster?** Yes — generate portrait and upscale. Portrait output is 1024 x 1536, the same 2:3 proportion an A0 sheet uses, and the built-in upscaler prepares it for large-format printing. A0 portrait is the usual expectation at European and international meetings. **Will it print at 48 x 36 inches?** Yes — generate landscape. 1536 x 1024 is the 3:2 proportion of a 48 x 36 board, the common US size. Check your own call for posters first: APA 2026 uses 6 x 4 ft boards and Sigma uses 96 x 48 in, and neither is 48 x 36. **What resolution do the templates print at?** Generate, then upscale before you send it to the printer. A 1024 x 1536 render is a draft resolution; the upscaler is what makes it large-format ready. Poster printing is viewed from a metre or more, so it tolerates far less resolution than a journal figure does. **Which research poster template fits my field?** Start from the venue, not the field. Classic Navy for conservative and clinical meetings; Modern Dark or Tech Gradient for computational and engineering work; Life Sciences for biology, ecology and medicine; Minimal Mono or Editorial Serif where the audience is design-literate. The table above sets out what each one emphasises. **Can I customize a template?** Yes — add custom instructions before generating (section order, what to emphasise, colours to keep) and regenerate freely. The template sets the visual language; your instructions steer the layout. Everything stays editable afterwards in the workspace. **How much text should a poster carry?** Far less than a paper. The University of Chicago library guide puts it at no more than 1,000 words including captions, with roughly 60% of the surface given to imagery. APA asks presenters for 18 pt or larger in a sans-serif face such as Arial or Calibri. --- ### Research Poster, Graphical Abstract & Illustration Examples URL: https://scientificfigure.com/examples Description: Browse real AI-generated examples: research poster examples, graphical abstract examples and scientific illustrations. See what's possible, then make your own. --- ### Graphical Abstract Examples — Journal-Ready Visual Summaries URL: https://scientificfigure.com/examples/graphical-abstract-examples Description: Browse graphical abstract examples across biology, chemistry and AI research. See how one clear left-to-right flow summarizes a paper — then generate your own. #### Frequently asked questions **What size do journals require for graphical abstracts?** Elsevier asks for 531×1328 px minimum (about 2.5:1), many others accept 16:9 or square. Generate at 16:9 and use the workspace aspect tool to match your journal's spec. **Can I make one from my actual paper?** Yes — paste your abstract or upload the PDF into our Graphical Abstract Maker. The AI extracts your real stages and findings and renders them with exact labels. **Which style works best?** Flat vector is the safest journal choice; gradient suits computational and materials work; hand-drawn sketch stands out in presentations and social media. --- ### Scientific & Research Poster Examples with Design Breakdowns URL: https://scientificfigure.com/examples/scientific-poster-examples Description: Research poster examples across machine learning, immunotherapy, neuroscience and more — each with a layout breakdown and A0 font-size specs. Make your own. #### Scientific poster examples FAQ **What size should a scientific poster be?** A0 portrait (841 × 1189 mm / 33.1 × 46.8 in) is the standard at most European and international conferences, and 48 × 36 inches landscape is the classic US format. Check your conference's call for posters first; A1 (594 × 841 mm) shows up at student symposia and department poster days. **What font size should a research poster use?** On an A0 poster: title 85–120 pt bold, authors 54–60 pt, section headings 36–44 pt, body text 24–32 pt and never below 24 pt, captions 18–20 pt. The test that matters is whether your body text is readable from about three meters. **How many words should a scientific poster have?** A scientific poster should carry 300 to 800 words in total. Most posters that fail do so by carrying two or three times that, which turns a 90-second scan into something nobody attempts. **What makes a good scientific poster?** A good scientific poster states one clear finding in the title, gives results the largest panel, keeps body text readable from three meters, and leaves roughly 40% whitespace. The reading path should be obvious enough that no viewer has to think about it — posters that win prizes are almost always the ones that cut the most. **How do I choose a poster layout?** Let your evidence pick the layout: several comparable figures suit a three-column classic, one commanding visual suits a figure-dominant layout, many equal-weight experiments suit a modular grid, and review or methods work suits a narrative single column. All four are broken down above. **Should a research poster be portrait or landscape?** Build whatever the conference board requires — this is not a design choice. European and international meetings usually specify A0 portrait; US conferences commonly use 48 × 36 inches landscape. Building portrait for a landscape board is an expensive mistake to discover on site. **Can I recreate these examples with my own research?** Yes — every example here was generated with our Scientific Poster Maker. Upload your paper PDF or paste your abstract, pick the same template, and your content is laid out in the same style. **Which poster style should I choose?** Match the style to the field and the venue: classic navy for clinical and conservative meetings, dark or gradient for AI and computational work, life-sciences green for biology and ecology, editorial serif for interdisciplinary and outreach settings, minimal for theory. The table above maps all six. **Are these real AI-generated posters?** Yes — every poster on this page came out of the poster maker using the template shown, with no manual redesign. The text is extracted from source material rather than invented, which is why the sections read as real research. **Where can I find more research poster examples?** University research offices publish large galleries of real conference posters, and they are worth studying for content density. For design patterns you can apply directly, the examples here are each paired with a breakdown of the layout decision behind them. --- ### Scientific Illustration Examples — 6 Styles Compared URL: https://scientificfigure.com/examples/scientific-illustration-examples Description: Browse scientific illustration examples — botanical plates, anatomical diagrams, ink line art, watercolor and flat vector — then generate your own free. #### Frequently asked questions **Are these real AI outputs?** Yes — every image on this page was generated with our illustration tool using the exact style presets you can pick, with no manual retouching. **Can I get the same subject in a different style?** Yes — describe your subject once and switch the style preset; each style is a tuned prompt over the same pipeline. **What resolution can I export?** Up to 4K depending on the model — enough for print figures, posters and covers. --- ## Guides ### Visual Abstract Maker — AI Generator for Clinical Papers URL: https://scientificfigure.com/visual-abstract Description: Turn a clinical abstract or paper PDF into a three-panel visual abstract — population, intervention, outcome — with your reported numbers. Free to start. #### Frequently asked questions **What is the difference between a visual abstract and a graphical abstract?** A visual abstract follows a fixed three-panel structure — population, intervention, outcome — reports effect sizes as numbers, and is made for dissemination after acceptance. A graphical abstract is a free-form visual flow of a study's mechanism, is submitted with the manuscript, and has strict per-publisher size requirements. See the comparison table above for the full breakdown. **Do journals require a visual abstract?** Almost none require one at submission. They are usually produced after acceptance, either by the journal's social media team or by the authors themselves. Some journals invite authors to supply one, and a growing number of conferences ask for them alongside accepted abstracts. **What size should a visual abstract be?** There is no formal specification, because it is not part of the manuscript package. Design for social feeds: a square (1:1) or 4:3 image at 2K resolution covers every platform, stays sharp after recompression and reads on a phone. If your journal supplies a house template, match that instead. **Is there a visual abstract template for PowerPoint?** Several journals and societies publish one, and it is worth asking your target journal before building your own. If you would rather not lay out boxes by hand, use the text template above as generation instructions — it encodes the same three-panel structure without the file. **Can I make a visual abstract with AI?** Yes, with the same caution that applies to any figure: the numbers must come from your paper and you are responsible for checking every one of them before you post. Our maker extracts labels and values from your text rather than inventing them, but proofread the rendered figure — a mistyped effect size in a widely shared image is much harder to retract than a link. **Do visual abstracts actually get more attention?** The format took off because the early work in the surgical literature found that articles shared as a visual abstract drew substantially more views than the same articles shared as text alone. Later results vary by field and by account size, so treat it as a reliable improvement in legibility rather than a guaranteed multiplier on your metrics. **Can I use a visual abstract for a systematic review?** Yes, and it works well. Swap the population panel for the included studies and participants, the intervention panel for the comparison, and the outcome panel for the pooled estimate with its confidence interval. Keep the number of included studies visible — it is what tells a reader how much weight the estimate carries. ---