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Biology IA Criteria Guide

Design a focused investigation, control variables cleanly, and evaluate with biological precision.

This guide keeps the Biology IA anchored to a clear research question, reliable data collection, uncertainty-aware processing, and a conclusion that is honestly supported by the evidence.

Assessment criteria

What each criterion measures, how many marks it carries, and what stronger evidence usually looks like.

Criterion names, marks and mark bands follow the IB subject guide. The band descriptions are our own summaries, so check your subject guide for the exact wording.

Criterion A: Research Design (6 marks)

How clearly the report sets out its research question in context and explains a method someone else could repeat.

Stronger evidence
The question is set in a specific, well-chosen context, method considerations are explained, and the method is detailed enough for someone else to repeat.
Early-stage evidence
The research question appears without context, method considerations are only mentioned, and the method is too thin for someone else to repeat.

Criterion B: Data Analysis (6 marks)

How clearly and precisely the report records and processes data, including uncertainties, in ways that answer the question.

Stronger evidence
Recording and processing are clear and precise, uncertainties are handled appropriately, and the processing is correct and relevant to the question.
Early-stage evidence
Recording and processing are hard to follow and imprecise, uncertainties are barely considered, and processing has major gaps or errors.

Criterion C: Conclusion (6 marks)

How well the conclusion answers the research question from the analysis and compares the result with accepted science.

Stronger evidence
The conclusion is justified, fully consistent with the analysis, and supported by a relevant comparison with accepted science.
Early-stage evidence
A relevant conclusion is given, but the analysis does not support it and the comparison with accepted science is superficial.

Criterion D: Evaluation (6 marks)

How well the report judges the weaknesses of its method and suggests realistic improvements.

Stronger evidence
The report explains how much each specific weakness affected the results and explains realistic improvements that target them.
Early-stage evidence
Only generic weaknesses are named, and realistic improvements are simply listed.

Mark bands

Want to know where your IA sits in these bands? Upload your draft and get a mark for each criterion.

Grade my IA

How to build it

Most weak drafts fail on order, not on ideas.

  1. 1

    Shape one focused question

    Pick a biological relationship that can be measured clearly and kept narrow enough to investigate well.

  2. 2

    Design for control

    Define variables, controls, and repeats so the method is reproducible and the data is worth trusting.

  3. 3

    Process data with care

    Show calculations, graphs, and uncertainty handling clearly so the analysis reads as scientific rather than descriptive.

  4. 4

    Evaluate against the evidence

    Link your conclusion to the data, compare it to biological context, and suggest improvements that directly address weaknesses.

Before you submit

  • Research question is specific and testable.
  • Methodology is detailed enough to replicate.
  • Raw and processed data are presented with units and uncertainty where relevant.
  • Conclusion and evaluation are grounded in the evidence, not guesswork.

Quick wins

  • State the independent, dependent, and controlled variables in one clean planning table.
  • Add uncertainty notes to the data table before writing the analysis.
  • Use one sentence at the end of each paragraph to tie back to the research question.

Turn Biology Data Into A Higher Band Draft

Marksy grades your Biology IA against IB criteria, highlights gaps in analysis and evaluation, and shows exactly what to improve before submission. The result includes a mark for every criterion, evidence from your draft, and the changes to make first.

Grade My Biology IASee Pricing
  1. 1

    Upload your IA draft as a PDF

  2. 2

    Get a mark and feedback for every IA criterion

  3. 3

    Revise and grade the new version

A mark for every criterion
A mark for every criterionSee where the draft is now, criterion by criterion.
Comments on your sentences
Comments on your sentencesEach comment points at the passage it is about.
What to fix first
What to fix firstConcrete next edits instead of "improve your analysis".