What is the easiest IB Biology IA topic to investigate?

Enzyme activity, seed germination, leaf-disc photosynthesis, and yeast respiration are among the most manageable topics because their variables can be controlled with standard school equipment. However, an easy procedure does not automatically produce a strong IA. You still need a focused research question, sufficient independent replicates, suitable measurement precision, and biological reasoning. A pilot study should confirm that the response changes detectably across your proposed independent-variable range. Choose the simplest investigation that gives you enough reliable data to conduct meaningful analysis and evaluation.

Does an IB Biology IA idea have to be completely original?

The investigation does not need to examine a phenomenon that has never been studied before. Originality can come from adapting the organism, environmental context, variable range, apparatus, or method of measurement. A standard catalase experiment, for example, can become an individual investigation through a justified choice of tissue, treatment, or quantitative technique. You must not copy another student’s question, wording, report, or dataset, and all borrowed methods and ideas require citation. The most useful form of originality is a design choice that has a clear biological reason rather than novelty added only to appear impressive.

How many values and repeats should a Biology IA have?

The IB does not prescribe one universal number of independent-variable values or repeats for every Biology investigation. Your design must instead provide enough relevant data to answer the research question reliably. For a continuous variable, several levels across a justified range usually reveal a trend more effectively than comparing only two conditions. Independent biological replicates are needed to estimate variation, while repeated instrument readings of one sample measure technical precision rather than biological variation. Decide the final numbers through a pilot study, the expected variability, ethical limits, available time, and the requirements of your planned statistical analysis.

Can I use humans in my IB Biology IA?

Human physiology investigations are possible only when they receive prior teacher approval and comply with school ethical and safety requirements. Participants must volunteer, understand the procedure, be able to withdraw, and have their identities protected in the report. Minors may require parental or guardian permission in addition to their own agreement, depending on local policy. Keep exercise within normal safe activity, provide recovery time, and never expose participants to drugs, dangerous substance doses, sleep deprivation, or medically risky procedures. A low-risk reaction-time or mild exercise investigation is generally more feasible than a study involving ingestion or invasive measurement.

Can I do a database Biology IA instead of a laboratory experiment?

The scientific investigation can accommodate different approaches, but your teacher must confirm that the proposed design meets the current Biology requirements. A database investigation needs a sharply defined biological question, credible datasets, justified selection criteria, and enough processing or analysis to demonstrate your own scientific reasoning. Simply reproducing a graph from an online source is not an adequate investigation. You must evaluate limitations such as inconsistent collection methods, missing values, confounding variables, geographic coverage, and the reliability of the original sources. A database approach is most suitable when the available data genuinely address a question that cannot be investigated safely or practically in school.

Which Biology IA topics should students avoid?

Avoid topics requiring pathogenic organisms, uncontrolled culturing of microbes from human or public surfaces, vertebrate harm, invasive human procedures, or exposure to unsafe chemicals. You should also avoid projects that depend on inaccessible equipment, months of plant growth, unpredictable wild-animal encounters, or an unrealistically large participant sample. Questions with several changing variables are difficult to interpret because any observed effect has multiple possible causes. Overused topics are not automatically unsuitable, but copying a standard method without thoughtful adaptation often produces a generic report. Reject any idea that cannot produce measurable repeated data, pass a teacher-approved risk assessment, or be completed within the school timetable.

50 IB Biology IA Ideas That Actually Work

RevisionDojo Team

•7/27/2026•16 min read

This site uses cookie tracking technologies. Learn more in our Cookie Policy.

50 IB Biology IA Ideas That Actually Work

RevisionDojo Team

•7/27/2026•16 min read

The best IB Biology IA ideas are not the most complicated. They are focused investigations with measurable variables, sufficient repeated data, manageable controls, and a biological mechanism you can explain. The 50 ideas below are designed for ordinary school laboratories and are grouped into enzymes, plants, ecology, human physiology, and microbiology.

Under the current course, first assessed in 2025, the Biology IA is officially called the scientific investigation. It contributes 20% of the final Biology grade, is allocated approximately 10 hours, and produces an individual written report of no more than 3,000 words. The four assessment criteria are Research design, Data analysis, Conclusion, and Evaluation, each worth six marks.

What makes a Biology IA idea workable?

A promising topic must become a precise research question. A useful structure is: “How does independent variable X affect dependent variable Y in organism or system Z, measured using method M?”

Before committing, apply these tests:

Measurable: The dependent variable produces quantitative data, not just observations.
Controllable: Important factors other than the independent variable can be standardized or monitored.
Repeatable: You can collect enough replicates across a sensible range of conditions.
Biological: The expected pattern can be explained using biological concepts rather than only chemistry or physics.
Safe and ethical: Your teacher can approve the organisms, materials, participants, and disposal method.
Feasible: The investigation fits the available equipment and timetable.

Originality does not require discovering an unknown phenomenon. It can come from the organism, variable range, measurement technique, or local context. Adapt an idea only after a pilot study confirms that its response is measurable.

For more planning detail, see RevisionDojo’s guides to designing an effective science IA experiment and writing a focused Biology IA.

Enzyme IB Biology IA ideas

Enzyme investigations are efficient because temperature, pH, concentration, and reaction time can usually be controlled closely. Avoid relying only on foam height when a gas sensor, colorimeter, glucose test, or timed endpoint can provide more precise data.

#	Investigation idea	Independent variable	Dependent variable
1	Catalase activity in potato tissue	Hydrogen peroxide concentration	Initial oxygen production rate
2	Effect of temperature on catalase	Reaction temperature	Oxygen volume produced per minute
3	Effect of pH on catalase from yeast	Buffer pH	Initial oxygen production rate
4	Catalase activity in differently aged potato tissue	Potato storage duration	Oxygen production rate per gram
5	Amylase digestion of starch	pH of reaction mixture	Time until iodine no longer turns blue-black
6	Temperature and amylase activity	Reaction temperature	Rate of starch disappearance
7	Lactase hydrolysis of lactose	Lactase concentration	Glucose concentration produced per minute
8	Competitive inhibition of lactase	Galactose concentration	Rate of glucose production from lactose
9	Pectinase and fruit juice extraction	Pectinase concentration	Filtered juice volume after a fixed time
10	Protease digestion of gelatin	Protease concentration	Change in gelatin mass or clearing time

A strong enzyme design measures the initial reaction rate, where possible, because substrate depletion and product accumulation increasingly affect later measurements. Conduct a pilot to choose a range that shows more than an all-or-nothing response.

Plant biology IA ideas

Fast-germinating seeds, leaf discs, duckweed, and pondweed suit school schedules. Plant experiments need careful control of seed batch, developmental stage, temperature, water availability, and light exposure.

#	Investigation idea	Independent variable	Dependent variable
11	Salinity and radish germination	Sodium chloride concentration	Germination percentage after a fixed period
12	Salt stress and early root growth	Sodium chloride concentration	Mean radicle length
13	pH and seed germination	Water or buffer pH	Germination percentage
14	Nitrate availability and duckweed	Nitrate concentration	Change in frond number or surface area
15	Phosphate availability and duckweed	Phosphate concentration	Relative growth rate
16	Light intensity and pondweed photosynthesis	Measured light intensity	Oxygen volume produced per minute
17	Light wavelength and photosynthesis	Light wavelength or filter color	Leaf-disc flotation rate or oxygen production rate
18	Bicarbonate and photosynthesis	Sodium bicarbonate concentration	Mean leaf-disc flotation time
19	Leaf age and chlorophyll content	Leaf developmental position	Chlorophyll absorbance per gram
20	Simulated acid rain and leaf membranes	Solution pH	Pigment leakage measured by absorbance

Counting pondweed bubbles is accessible but imprecise because bubble sizes vary. Collecting gas volume or using a dissolved oxygen probe improves measurement validity. RevisionDojo’s sample Biology IA investigation illustrates how variables and controls can be developed from a photosynthesis topic.

Ecology IA ideas

Ecology investigations can produce authentic local data, but field conditions create confounding variables. Use standardized quadrats or transects, record environmental variables consistently, and avoid claiming causation from a correlational study.

#	Investigation idea	Independent variable	Dependent variable
21	Distance from a footpath and plant abundance	Distance from path	Percentage cover of a selected species
22	Trampling and species richness	Measured trampling intensity or path distance	Plant species richness per quadrat
23	Soil moisture and moss cover	Soil moisture percentage	Moss percentage cover
24	Canopy cover and understory diversity	Canopy cover percentage	Understory species richness
25	Light intensity and clover abundance	Ground-level light intensity	Clover density per quadrat
26	Soil pH and plant distribution	Soil pH	Abundance of a selected plant species
27	Distance from water and invertebrate abundance	Distance from pond or stream edge	Invertebrate count per standardized sample
28	Leaf-litter depth and decomposer abundance	Leaf-litter depth	Number of visible detritivores per sample
29	Water flow and algal cover	Local flow velocity	Algal percentage cover on comparable surfaces
30	Urbanization and lichen coverage	Distance from a road or traffic intensity	Lichen percentage cover on standardized tree area

Choose sampling points using a systematic or random method rather than selecting visually interesting locations. Correlation, regression, diversity indices, or comparisons between defined groups may be appropriate, but the analysis must match the type and distribution of the data.

Human physiology IA ideas

Human investigations require informed consent, privacy, voluntary participation, and prior school approval. Keep activities within normal everyday or physical education intensity, allow withdrawal, anonymize results, and exclude participants where normal exercise would be unsuitable. Do not administer drugs, supplements, allergens, extreme diets, sleep deprivation, or unsafe exercise.

#	Investigation idea	Independent variable	Dependent variable
31	Exercise duration and heart-rate recovery	Duration of standardized step exercise	Time to return near resting heart rate
32	Exercise intensity and pulse rate	Step cadence	Change in heart rate
33	Recovery posture and heart rate	Seated versus standing recovery posture	Heart-rate reduction after a fixed interval
34	Warm-up duration and recovery	Warm-up duration	Post-exercise heart-rate recovery time
35	Hand temperature and grip endurance	Hand-warming duration or safe water temperature	Grip duration at standardized force
36	Dominant versus non-dominant hand response	Hand dominance condition	Ruler-drop reaction distance
37	Background sound and reaction time	Sound condition or measured sound level	Computer-recorded reaction time
38	Visual distraction and reaction time	Number of visual distractors	Mean reaction time
39	Breathing rate after exercise	Exercise duration	Time for breathing rate to return near baseline
40	Familiarity and short-term recall	Familiar versus unfamiliar word category	Number of words recalled after a fixed delay

Some of these designs are repeated-measures investigations rather than simple continuous-variable experiments. Counterbalance treatment order and provide adequate recovery to reduce fatigue and learning effects. Follow your teacher’s risk assessment rather than assuming that an everyday activity is automatically approved.

Microbiology IA ideas

School microbiology must use approved organisms and aseptic procedures under teacher supervision. Guidance from the Microbiology Society recommends school cultures normally be incubated around 20 to 25°C and not above 30°C, reducing the likelihood of encouraging human pathogens. Plates should remain secured and must be sterilized before disposal according to school procedures.

#	Investigation idea	Independent variable	Dependent variable
41	Sugar concentration and yeast respiration	Glucose concentration	Carbon dioxide production rate
42	Sugar type and yeast respiration	Type of equal-concentration sugar	Carbon dioxide volume after a fixed time
43	Temperature and yeast respiration	Incubation temperature	Carbon dioxide production rate
44	pH and yeast fermentation	Initial solution pH	Carbon dioxide production rate
45	Salt stress and yeast respiration	Sodium chloride concentration	Carbon dioxide production rate
46	Preservatives and yeast growth	Approved preservative concentration	Change in turbidity or absorbance
47	Temperature and yogurt acidification	Incubation temperature approved by teacher	Rate of pH decrease
48	Starter concentration and yogurt fermentation	Yogurt starter concentration	Time to reach a defined pH
49	Approved disinfectant and safe bacterial culture	Disinfectant concentration	Zone of inhibition diameter
50	Plant extract and an approved microbial strain	Plant extract concentration	Zone of inhibition diameter

Ideas 49 and 50 are appropriate only if your school supplies a known, non-pathogenic culture and approves the protocol. Do not culture unknown microorganisms from phones, skin, toilets, or public surfaces. Yeast respiration is usually a safer and more controllable alternative.

How to turn an idea into a strong investigation

First, run a small pilot study. Test the measurement method, estimate variability, check that the independent-variable range produces a detectable response, and identify controls you had overlooked.

Then refine the design:

Define one clear independent variable and a quantitative dependent variable.
Use a control treatment where biologically meaningful.
Select several justified levels across an appropriate range.
Plan independent replicates, not repeated readings of the same sample presented as separate organisms.
Record measurement uncertainty and relevant qualitative observations.
Choose analysis because it answers the question, not because it appears sophisticated.

The assessment rewards the quality of your reasoning across all four criteria. A simple investigation with reliable measurements and a specific evaluation is usually stronger than an ambitious investigation with weak controls. RevisionDojo’s guides to science IA statistics and Biology IA exemplars can help you evaluate possible approaches without copying another student’s work.

Common mistakes to avoid

Choosing a topic before checking equipment, organism availability, safety, and time.
Using vague outcomes such as “health,” “growth,” or “effectiveness” without an operational definition.
Changing several independent variables simultaneously.
Collecting too little data to distinguish a pattern from random variation.
Treating correlation as proof that one ecological variable caused another.
Writing generic limitations such as “human error” instead of explaining a specific source, its likely effect, and a realistic improvement.
Copying a published IA question, dataset, wording, or method without meaningful adaptation and citation.

The IB permits responsible AI use, but AI-generated material is not automatically your own work. Any AI-produced text or other material included in assessed work must be acknowledged according to IB and school requirements. Jojo AI and the RevisionDojo Biology IA Grader can support planning and rubric-based review, but your decisions, data, analysis, and final report must remain your own.

Conclusion

Successful IB Biology IA ideas combine original adaptation, reliable measurement, biological explanation, and realistic scope. Select two or three candidates, discuss safety and resources with your teacher, and pilot the strongest option before finalizing the question. After completing the investigation, use RevisionDojo’s IB Biology Questionbank for linked data-analysis practice and the IB Biology past paper video solutions to strengthen the exam skills developed through your IA.