How Do I Write An IB Bio IA?

What exactly are you writing?

Forget just collecting data—this is about showing real scientific thinking, ethical conduct, and clear communication. Topics can’t involve human or animal harm, must align with the IB syllabus, and fit within strict time and word limits. As of 2026, the IB hasn’t updated IA requirements since the 2023 syllabus revision, so the 2023 guide remains the go-to source IB Biology Subject Guide (2023).

Watch out for vague research questions, poor variable control, or word counts that balloon past 2,200. Plan early and use the IB rubric as your checklist throughout the process.

How do you actually write an IB Biology IA?

Step 1: Pick a lab experiment (not a database IA)

Your experiment should:

• Test a specific hypothesis.
• Use measurable variables (think enzyme activity over time or photosynthesis rate under different light intensities).
• Run within 10 hours of lab time.
• Follow IB’s ethical guidelines (no harmful procedures on humans or animals).

Good examples include checking how pH affects enzyme activity, measuring osmosis in potato cells, or testing how nutrient concentration impacts plant growth. Skip experiments that need fancy or hard-to-get equipment.

Step 2: Craft a research question

For instance:

• Weak: “What happens when you change the sugar in yeast?”
• Strong: “How does sucrose concentration (0.5%, 1.0%, 1.5%) affect the rate of CO₂ production in Saccharomyces cerevisiae over 10 minutes?”

Make sure your question is ethical and doable with the resources you have.

Step 3: Draft a hypothesis and identify your variables

For example:

“If the sucrose concentration increases from 0.5% to 1.5%, then the rate of CO₂ production in yeast will increase linearly.”

Define your controlled variables (like temperature, yeast amount, or time intervals) to keep your test fair. The IB really cares about variable control in the Exploration section IB Biology Subject Guide (2023).

Step 4: Write the method section

Write in past tense and passive voice: “The yeast solution was prepared by dissolving 1g of dried Saccharomyces cerevisiae in 100 mL of distilled water.” Don’t forget sample sizes and replication—test each sucrose concentration three times, for example.

Step 5: Collect your raw data

Use tools like a data logger or stopwatch for accuracy. The IB wants raw data in an appendix, so keep it neat and organized IB Biology Subject Guide (2023).

Step 6: Process your data and create graphs

Your graph should have:

• X-axis: Independent variable (e.g., sucrose concentration).
• Y-axis: Dependent variable (e.g., CO₂ production rate).
• Error bars showing standard deviation.
• A line of best fit (if it makes sense).

Use software like Excel, Google Sheets, or Logger Pro. Label everything clearly and add a figure caption, like: “Figure 1: The effect of sucrose concentration on CO₂ production in yeast (n=3, mean ± SD).”

Step 7: Write the Analysis section

For example:

• Describe trends: “CO₂ production increased with sucrose concentration up to 1.0%, then plateaued.”
• Refer to theory: “Yeast ferments sucrose via glycolysis, producing CO₂ as a byproduct.”
• Use stats if relevant (the IB doesn’t require them but rewards their use in top-scoring IAs) IB Biology Subject Guide (2023).
• Explain anomalies: “The 1.5% trial showed a lower rate than 1.0%, likely due to substrate inhibition.”

Step 8: Evaluate your experiment

Include:

• Sources of error (like human reaction time in counting bubbles).
• How errors impacted your results.
• Ways to improve (e.g., “Use a CO₂ sensor for more accurate readings”).

The Evaluation section is worth 6 of 24 points, so don’t skip it IB Biology Subject Guide (2023).

Step 9: Write the Conclusion

Keep it short (2–3 sentences). For example:

“The data supported the hypothesis that CO₂ production increases with sucrose concentration up to 1.0%, but not beyond. This suggests substrate saturation of yeast enzymes at higher concentrations.”

Don’t introduce new data or ideas here.

Step 10: Add Personal Engagement and polish Communication

For Personal Engagement, share your motivation: “I chose this experiment because I’m interested in fermentation, a process used in baking and biofuel production.”

For Communication, make sure your report is clear, concise, and well-organized. Use subheadings, scientific terms, and proper citations. This section is worth 4 points IB Biology Subject Guide (2023).

What if your IA isn’t working? Troubleshooting tips

1. Your experiment didn’t give clear results

Try these fixes:

• Check variable control (e.g., temperature fluctuations).
• Increase sample size (run more trials).
• Adjust the IV range (e.g., try 0.1%–1.0% instead of 0.5%–1.5%).

If the problem sticks around, ask your teacher for help. The IB expects unexpected results—just explain them in your Evaluation section IB Biology Subject Guide (2023).

2. You’re over the word limit

Try these tricks:

• Remove redundant explanations (like basic lab procedures).
• Combine paragraphs where possible.
• Use bullet points for lists (e.g., apparatus).
• Replace long sentences with concise alternatives.

The IB uses word-counting software, so manual checks won’t cut it. Use Microsoft Word’s “Review > Word Count” feature to track your progress Microsoft Word Support.

3. You’re unsure how to structure a section

Here’s a quick breakdown:

Section	What to Include
Personal Engagement	Why you chose the topic and how it connected to your learning.
Exploration	Research question, hypothesis, variables, method, apparatus, safety, and ethical considerations.
Analysis	Data trends, biological theory, graphs, and statistical analysis (if applicable).
Evaluation	Limitations, errors, impact on results, and suggestions for improvement.
Communication	Clarity, organization, scientific language, and proper citations.

Use this table as a checklist. If a section feels weak, draft it first and refine later.

How do you avoid common IA pitfalls?

Plan ahead and work efficiently

Here’s a simple timeline:

• Week 1: Choose topic, draft research question, and write method.
• Week 2: Run the experiment and collect raw data.
• Week 3: Process data, create graphs, and draft Analysis/Evaluation.
• Week 4: Write Introduction, Personal Engagement, and Conclusion. Edit for clarity and word count.

Rushing leads to mistakes and lower grades. The IB recommends finishing the experiment by Week 3 to leave time for reflection and editing IB Biology Subject Guide (2023).

Use the IB rubric as your roadmap

Focus on:

• Exploration: “Detailed method,” “Variables clearly defined.”
• Analysis: “Data logically processed,” “Trends explained with biological theory.”
• Evaluation: “Limitations discussed,” “Suggestions for improvement.”

Check your draft against the rubric before submitting. If a section doesn’t hit a criterion, revise it.

Get feedback early and often

Ask for feedback on:

• Clarity of your research question.
• Logical flow of your method.
• Accuracy of your data processing.
• Strength of your Evaluation section.

Use a red pen to mark changes so you can track progress. Peer review mimics the moderation process and helps you spot gaps IB Biology Subject Guide (2023).

Follow formatting rules to the letter

Requirements include:

• Font: Arial or Times New Roman, 12pt.
• Spacing: Double-spaced (1.5 spacing isn’t acceptable).
• Margins: 2.54 cm (1 inch) on all sides.
• Pages: 12 maximum (title page and raw data appendix excluded).
• Words: 2,200 maximum (title page, table of contents, and raw data excluded).
• Title Page: Include title, your name, candidate number, school name, and session year.

Use Microsoft Word’s “Styles” feature to keep formatting consistent Microsoft Word Support.

Steer clear of ethical mistakes

Skip experiments like:

• Testing reaction times on classmates.
• Dissecting animals (unless pre-approved by the IB).
• Using concentrated acids without supervision.

If your topic needs ethical approval, submit a proposal to your teacher well in advance. The IB’s ethical guidelines are strict, and violations can mean a zero IB Biology Subject Guide (2023).