The IB Biology Internal Assessment (IA) is your chance to become a scientist — not just a student completing a lab. You’ll design, carry out, and evaluate your own experiment based on a research question that genuinely interests you.
If you’re still stuck on what to investigate, don’t worry — we’ve gathered 25 high-quality IB Biology investigation ideas across molecular, environmental, and physiological topics to help spark inspiration and show you how to meet IB standards.
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🧠 Before You Pick a Topic: What Makes a Strong IB Biology IA?
According to the Diploma Collective Step-by-Step Science IA Guide, the best Biology IAs are:
Focused — test one clear, measurable relationship
Feasible — doable in 10 hours with school equipment
Ethical — no harm to animals or humans, with proper safety
Quantitative — produces measurable data you can analyze statistically
Original — avoids generic textbook experiments by adding a new angle
Example:
❌ Weak: “How does temperature affect enzymes?”
✅ Strong: “How does changing the pH from 4–8 affect the rate of catalase activity in apples, measured by oxygen bubble volume?”
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🌿 IB Biology Investigation Ideas by Topic
1. Enzyme Activity & Biochemical Processes
Effect of substrate concentration on amylase activity (measured by starch disappearance).
How different plant sources of catalase (potato vs. spinach vs. bean) affect reaction rate.
Impact of natural inhibitors (like lemon juice or green tea extract) on enzyme performance.
Influence of detergents or alcohol on membrane permeability in beetroot cells.
How boiling vs. freezing affects enzyme recovery post-denaturation.
2. Photosynthesis & Plant Physiology
Effect of light wavelength (red, blue, green) on photosynthetic rate using a color filter.
Relationship between CO₂ concentration and photosynthesis rate (via floating leaf discs).
Does leaf age influence photosynthetic efficiency in the same species?
How soil salinity affects plant germination and growth.
Comparison of organic vs. synthetic fertilizers on plant chlorophyll content.
3. Human Physiology & Health
Effect of energy drink caffeine concentration on heart rate recovery after exercise (with ethical consent).
Influence of temperature on human reaction time (using digital timing tests).
How music tempo affects concentration or heart rate variability.
Relationship between hydration level and grip strength.
Correlation between sleep duration and short-term memory recall accuracy.
4. Ecology & Environment
How urbanization level affects species diversity in local green spaces (Simpson’s Index).
Impact of soil pH on earthworm abundance or microbial activity.
Comparison of biodiversity in shaded vs. sun-exposed microhabitats.
How road proximity influences lichen or moss coverage as a measure of air pollution.
Using aquatic plant growth as a bioindicator for water quality across different local streams.
5. Genetics, Evolution & Cellular Biology
The effect of UV exposure on yeast mutation frequency (safe light sources only).
How temperature affects mitosis rate in onion root tips.
Genetic diversity comparison between native and invasive plant populations using leaf morphology or available datasets.
Relationship between antibiotic concentration and bacterial colony inhibition zones.
Investigating microplastic exposure effects on seed germination rate (ethical, simulated setup).
💡 Expert Tips from the Diploma Collective IA Guide
1. Combine Methods:
You can merge lab data with simulations or databases — for example, testing local plant growth and comparing your data to FAO climate datasets for stronger evaluation.
2. Run a Pilot Trial:
Always test your ranges early. If your data is too flat or inconsistent, adjust before committing to a full experiment.
3. Use Statistics:
Biology IAs should include averages, standard deviation, and graphs with error bars. IB values depth over complexity.
4. Reflect Ethically:
Never harm animals or use humans without informed consent. You can always model processes with simulations like PopEcoLab or explore datasets from WHO or UN FAO.
How to Turn an Idea into a Strong Research Question
Start broad → narrow it down → make it measurable.
Example Path:
Topic: Plant Growth
Focus: Fertilizer Type
Question: How does increasing organic fertilizer concentration from 0–20% affect the average height of radish plants after 14 days of growth under constant light conditions?
This phrasing ensures your question is focused, measurable, and IB-aligned.
Final Tip: Don’t Just Pick a Topic — Pick a Story
Your IA isn’t just about data; it’s about showing how you think like a biologist.
Connect your experiment to a real-world issue — from sustainable agriculture to human health — and you’ll stand out.
Ready to Start Your Biology IA?
Get our Elite IB Student Membership to access the full Step-by-Step Science IA Guide, covering every stage — from writing your research question to mastering evaluation.
You’ll also unlock 9 more premium IB resources across Economics, Math, TOK, Business, and more.
For more information about the IB Biology course and IA, visit https://www.ibo.org/
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