Biology IA structure: sections, criteria and word count

At a glance

The structure, section by section

1. Header block

Required by the IB · No criterion (formal requirement) · Outside the word count

Title, alphanumeric candidate code, group members' codes, word count.

1. Enter a working title.
2. Add your candidate code.
3. Add each group member's code if you worked in a group.
4. Insert the counted word total from the counter.

2. Research question

Required by the IB · Criterion: Research design

1 focused question naming the IV and DV (or 2 correlated variables) and the system studied; every student needs their own. Moderator comments flag a question that omits the IV's range.

1. Name the IV with its units and planned range.
2. Name the DV and how you will measure it.
3. State the organism, material, system or data set.
4. Check that quantitative data can answer it in the time you have.
5. In a group, check that your IV, DV or data subset differs from the others'.

3. Background and scientific context

Rewarded by a criterion · Criterion: Research design, Conclusion

Only the theory the question depends on, the expected relationship or model, and the accepted values to compare with later.

1. List the concepts your question relies on.
2. Explain each one briefly and cite it.
3. Give the governing equation or expected trend.
4. Record the reference values you will compare against.
5. Delete theory you will not use again.

4. Hypothesis or prediction

Common practice · No criterion directly (supports Conclusion)

The expected direction or form of the relationship. Forming hypotheses is a listed inquiry skill; no criterion names it.

1. State the expected direction or shape of the relationship.
2. Justify it from your background section.

5. Variables

Rewarded by a criterion · Criterion: Research design

The IV (levels, range, interval), the DV (method, instrument, resolution) and each controlled variable with how it was held constant, often as a table. Moderator comments flag weak control of variables.

1. Define the IV and justify its range and interval.
2. Define the DV and the instrument that measures it.
3. List each control variable, its possible effect and how you kept it constant.
4. Note any factor you could not control and how you monitored it.

6. Methodological considerations

Rewarded by a criterion · Criterion: Research design

Why this method, the number of IV values and repeats, what the pilot changed, how a database, model or field sample was chosen, and for field or survey work the sampling design and sample size.

1. Justify your measurement method against the alternatives.
2. Justify the number of IV values and repeats.
3. Summarise what your pilot run changed.
4. Explain how you sampled or selected data.
5. For field or survey work, describe the site and the sampling design, random or systematic, with the quadrat or transect size.
6. Justify your sample size and say how you reduced sampling error.
7. State your key assumptions.

7. Safety, ethics and environment

Rewarded by a criterion · Criterion: Research design

Hazards and controls, the ethics of working with organisms, people or secondary data, disposal and environmental impact. Assessed under Research design; the teacher checks it before data collection, and practical skills themselves are no longer assessed.

1. List each hazard and its control.
2. Animals: get your teacher's approval before any live-animal work, apply replacement, refinement and reduction with replacement first, and observe natural behaviour only.
3. People: get written consent, with written parent or guardian consent under 16, keep results anonymous, let volunteers withdraw at any time and use no body fluids except your own saliva or sweat.
4. Chemicals, equipment and microorganisms: write a risk assessment and a disposal plan under your local safety rules.
5. Secondary data: use data from approved, licensed or published research, or data judged ethical when they were collected, and never data judged unethical in their own time.
6. Describe waste disposal and any environmental effect, including the effect of fieldwork.
7. Record your teacher's approval where one is needed.

8. Materials and apparatus

Rewarded by a criterion · Criterion: Research design

Each item with size, concentration or model; each instrument's resolution or uncertainty; where organisms, chemicals or data came from.

1. List each item with its size, concentration or model.
2. Give each instrument's resolution or uncertainty.
3. Name the source of organisms, chemicals or data sets.

9. Procedure

Rewarded by a criterion · Criterion: Research design

Steps detailed enough to repeat in principle, with no padding.

1. Write numbered steps in order.
2. Include quantities, timings and settings.
3. Say how you kept each control constant.
4. Say when and how you took readings.
5. Cut duplicate or generic steps.
6. Add a labelled set-up diagram or photo if it saves words.

10. Data source and selection

Rewarded by a criterion (Research design covers selecting data, the choice of database and how data were sampled) · Criterion: Research design · Only when it applies

For a database or secondary-data investigation, use this in place of Materials and apparatus and Procedure: where the data came from and how you chose them. A class-built database with standard protocols counts as a database investigation.

1. Name the database or provider and your access date.
2. Describe how the original data were produced.
3. State inclusion and exclusion criteria.
4. Explain how you filtered or sampled records.
5. Map fields to your IV, DV and controls.
6. Note the precision or variability the source reports.

11. Model and settings

Rewarded by a criterion (the choice of model is part of Research design) · Criterion: Research design · Only when it applies

For a simulation or model investigation, use this in place of Materials and apparatus and Procedure: the model, its settings and its assumptions.

1. Name the simulation and its version.
2. List the fixed parameters and the IV settings.
3. Say how you read outputs and at what resolution.
4. State the model's assumptions for your evaluation.

12. Raw data

Rewarded by a criterion · Criterion: Data analysis

Every trial with units and ± uncertainty; qualitative observations where relevant. Quantitative data are required.

1. Tabulate every trial with units and ± uncertainty in the column headers.
2. Match decimal places to each instrument's resolution.
3. Add a short table of observations.
4. Flag anomalies and keep them in the table.

13. Data processing

Rewarded by a criterion · Criterion: Data analysis

Each processing step and its purpose, worked examples, uncertainties and any statistics, with the test named and matched to the data; secondary data also need an uncertainty treatment.

1. State each processing step and its purpose, such as means, rates, percentage change, magnification or a diversity index.
2. Show 1 worked example per calculation type.
3. Give the uncertainty as a range, SD or SE of your repeats, or as the instrument's precision, and say which.
4. If your design calls for a statistical test, name it and say why it fits: counts suit chi-squared, 2 means suit a t-test, and relationships suit r or R².
5. Justify how you treated outliers.

14. Processed results: tables and graphs

Rewarded by a criterion · Criterion: Data analysis

The processed-data table and graphs with error bars and a best fit; every table and figure numbered, titled and labelled with units. Moderator comments flag missing error bars when SD was calculated.

1. Build the processed-data table.
2. Choose a graph type that fits your data.
3. Add error bars and a line or curve of best fit.
4. Say in each caption what the error bars show: SD, SE or range.
5. Number, title and label every figure and table with units.
6. Refer to each one in your text.

15. Analysis and interpretation

Rewarded by a criterion · Criterion: Data analysis, Conclusion

The trend and its mathematical form, with gradients, intercepts or test statistics and their uncertainties.

1. Describe the trend and its mathematical form.
2. Quote gradients, intercepts or test statistics with their uncertainties.
3. Judge whether differences exceed the uncertainty or spread.
4. Link the pattern back to your question.

16. Conclusion

Rewarded by a criterion · Criterion: Conclusion

A direct answer consistent with the analysis and its uncertainties, justified against cited scientific context.

1. Answer the question with your processed values.
2. State how strongly the data support the answer, given the uncertainties.
3. Compare with the cited literature or accepted value.
4. Explain the agreement or the gap.

17. Evaluation

Rewarded by a criterion · Criterion: Evaluation

Specific weaknesses (control, precision, spread) and limitations (range, system, assumptions), the relative impact of each, and a realistic improvement for each.

1. Name specific weaknesses and limitations.
2. Estimate how much each one affects the conclusion.
3. Order them by impact.
4. Pair each one with a realistic, concrete improvement.
5. Add strengths or extensions only if words remain.

18. References

Required by the IB · Criterion: Conclusion (traceable context) · Outside the word count

Every source of theory, values, data and images in 1 standard style; missing or improper referencing counts as malpractice.

1. Cite each source where you use it.
2. Keep 1 style throughout.
3. Add access dates for online sources.
4. Make every literature value traceable.

19. Appendices

Common practice · No criterion · Only when it applies

Optional. The IA rules say nothing about appendices, and moderator comments say relevant material belongs in the body.

1. Keep everything that earns marks in the body.
2. Use an appendix only for long raw data, and only if your teacher allows it.

What counts toward the limit

Counts the running prose from the research question to the evaluation, plus explanatory footnotes. Captions and any appendix prose count as a precaution, because the IA rules do not address them; headings, tables, graphs, diagrams and their labels, equations, worked calculations, citations, the reference list and the header block are left out.

The limit: 3,000 words. The guide states no rule on going over, so treat it as a hard cap.

Graphs and visuals

• Raw data table with ± uncertainties Table, very common
  Units and ± in the headers; decimal places matched to instrument resolution; numbered title; outside the word count.
• Processed data table (means, spread or propagated uncertainty) Table, very common
  The derived quantity with its uncertainty; consistent precision per column.
• DV against IV graph with error bars and a line or curve of best fit Plotted, very common
  Axis titles with quantity and unit; error bars; linear or curve fit; interpolation and extrapolation; show the trendline equation and R², which the Biology tools list names. Moderators flag missing error bars.
• Worked sample calculations, with uncertainty propagation Math, common
  1 example per calculation type; outside the word count.
• Variables table (IV, DV, controls and how each was controlled) Table, common
  Lists the IV, the DV and each control with how it was kept constant, as the Research design clarifications ask.
• Qualitative observations table Table, common
  For qualitative data where relevant.
• Apparatus diagram or set-up photo Drawn, common
  Labels in course terms; no identifying faces or names.
• Risk, ethics and environment table Table, common
  Hazard, risk, control and disposal.
• Evaluation table (weakness, effect on the result, improvement) Table, common
  Tables are outside the count, so the reasoning in cells still has to read clearly.
• Bar chart of means with SD or SE error bars Plotted, very common
  Suits a categorical IV; the caption says what the bars show: SD, SE or range.
• Scatter graph with trendline, r and R² Plotted, common
  Common in correlational, field and database work; show the equation, R² and r with its sign.
• Line or curve graph (rates, time courses) Plotted, common
  Take a rate from a gradient or tangent.
• Box-and-whisker plot Plotted, occasional
  Median, IQR, whiskers and optional outlier markers.
• Histogram Plotted, occasional
  State the class intervals.
• Log-scale graph Plotted, occasional
  Label the log axis.
• Pie chart Plotted, rare
  The guide names it, but it seldom fits a research question.
• Statistical test summary Table, common
  Test, statistic, degrees of freedom, critical or p value and decision, with the null hypothesis and significance level stated.
• Micrograph or photo with scale bar Image, occasional
  Scale bar and magnification calculation.
• Diversity or abundance index working Math, occasional
  Mostly in fieldwork: Simpson reciprocal index, Lincoln index.
• Dichotomous key, pedigree chart, food web Drawn, rare
  Syllabus skills that seldom appear as IA outputs.

The frequencies are our estimates, from what the IB guide expects and what teachers advise. We did not count them in marked work.

Citations

The IB prescribes no style; use 1 standard style consistently, with author, date, title, page numbers where they apply and access dates for online sources. APA is the workspace default for science work, and your school may name another.

The workspace keeps your sources and writes the bibliography in APA 7th to start with. You can switch to MLA 9th, Chicago author-date, Chicago notes (footnotes) or Harvard at any point.

Pitfalls

• Name the IV with its range, the DV and the system in your research question, and keep the context narrow.
• Write a method that others could repeat, with no generic padding and enough IV values, repeats and samples for relevant, sufficient data.
• Add error bars whenever you calculate SD, and say in the caption whether they show SD, SE or range.
• Support the conclusion with your analysis, and compare it with cited scientific context.
• Give each evaluation point a relative impact and a realistic improvement, and cut generic points.
• Keep raw data and method writing individual in a group, and keep everything that earns marks in the body.

The workspace is free with an account, and it never writes or rewrites your text. What we will and will not do with your coursework →

Sources

• IB, Examiner Instructions 2027: Sciences, Biology
• IB, "Biology in the DP"
• IB, "Read curriculum updates" (page last updated 24 March 2026)
• Biology guide, Diploma Programme, first assessment 2025 (published Feb 2023, updated May 2023)
• Guidelines for the use of animals in IB World Schools (IB, ©2015; includes human subjects and secondary data)
• Extended essay guide, first assessment 2027 (published Feb 2025, updated May 2025 and Aug 2025)

The IB documents behind this page, checked 29 October 2026. The linked ones are on ibo.org; the others are IB documents we read in copies hosted elsewhere, so we name them without a link. Everything above is in our own words: the official wording is in your subject guide, which your coordinator can give you. LimeAdmissions is independent of the International Baccalaureate Organization, which has not endorsed this page. Every coursework structure →