IB Biology is assessed by two written papers, worth 80% of the grade, and the internal assessment, worth 20%. Here is how each paper is set out at SL and HL, what each section tests, what the command terms mean and how markschemes are read.
The weightings are the same at both levels: Paper 1 is 36%, Paper 2 is 44% and the internal assessment is 20%. HL papers are longer and include the additional higher level (HL only) content. Both papers can test any theme, and calculators are allowed in both.
| Paper | Time | Marks | Weighting | Questions |
|---|---|---|---|---|
| Paper 1 | 1 hour 30 minutes | 55 | 36% | Two booklets, 1A and 1B, sat together without a break |
| Paper 1A | Shared | 30 | 30 multiple-choice questions on SL material | |
| Paper 1B | Shared | 25 | 4 data-based questions on experimental work and the syllabus, across all themes | |
| Paper 2 | 1 hour 30 minutes | 50 | 44% | |
| Section A | 34 | A data-based question and short-answer questions on SL material | ||
| Section B | 16 | Extended-response questions: answer 1 of 2 |
| Paper | Time | Marks | Weighting | Questions |
|---|---|---|---|---|
| Paper 1 | 2 hours | 75 | 36% | Two booklets, 1A and 1B, sat together without a break |
| Paper 1A | Shared | 40 | 40 multiple-choice questions on SL and HL material | |
| Paper 1B | Shared | 35 | 4 data-based questions on experimental work and the syllabus, across all themes | |
| Paper 2 | 2 hours 30 minutes | 80 | 44% | |
| Section A | 48 | A data-based question and short-answer questions on SL and HL material | ||
| Section B | 32 | Extended-response questions: answer 2 of 3 |
The guide gives no separate time for 1A and 1B: you decide how to split the Paper 1 time between the two booklets. In each paper, about half the marks are for knowing and applying biology (AO1 and AO2) and half for formulating, analysing and evaluating (AO3).
30 questions at SL and 40 at HL, on any theme. No marks are taken off for wrong answers.
Four questions “related to experimental work and the syllabus”. This is where the guide’s practical skills (the Tools and the Inquiry process) are mostly tested, usually through data you have not seen before.
A data-based question, then short-answer questions on the syllabus (SL material at SL; SL and HL material at HL).
You choose one question of two at SL, and two of three at HL. At HL each Section B question is worth 16 marks; in the HL markscheme we checked, 15 of those are for content and 1 is for clarity of communication.
Each question starts with a command term that tells you what kind of answer earns the marks. These are the IB’s definitions from the Biology guide, grouped by assessment objective.
Watch out: in IB Biology, compare means similarities only. If a question wants differences as well, it says compare and contrast. Distinguish means differences only. Many other exam boards use “compare” for both.
| Term | Definition | Objective |
|---|---|---|
| Define | Give the precise meaning of a word, phrase, concept or physical quantity. | AO1 |
| Draw | Represent by means of a labelled, accurate diagram or graph, using a pencil. A ruler (straight edge) should be used for straight lines. Diagrams should be drawn to scale. Graphs should have points correctly plotted (if appropriate) and joined in a straight line or smooth curve. | AO1 |
| Label | Add labels to a diagram. | AO1 |
| List | Give a sequence of brief answers with no explanation. | AO1 |
| Measure | Obtain a value for a quantity. | AO1 |
| State | Give a specific name, value or other brief answer without explanation or calculation. | AO1 |
| Annotate | Add brief notes to a diagram or graph. | AO2 |
| Calculate | Obtain a numerical answer showing the relevant stages in the working. | AO2 |
| Describe | Give a detailed account. | AO2 |
| Distinguish | Make clear the differences between two or more concepts or items. | AO2 |
| Estimate | Obtain an approximate value. | AO2 |
| Identify | Provide an answer from a number of possibilities. | AO2 |
| Outline | Give a brief account or summary. | AO2 |
| Analyse | Break down in order to bring out the essential elements or structure. | AO3 |
| Comment | Give a judgement based on a given statement or result of a calculation. | AO3 |
| Compare | Give an account of the similarities between two (or more) items or situations, referring to both (all) of them throughout. | AO3 |
| Compare and contrast | Give an account of similarities and differences between two (or more) items or situations, referring to both (all) of them throughout. | AO3 |
| Construct | Display information in a diagrammatic or logical form. | AO3 |
| Deduce | Reach a conclusion from the information given. | AO3 |
| Design | Produce a plan, simulation or model. | AO3 |
| Determine | Obtain the only possible answer. | AO3 |
| Discuss | Offer a considered and balanced review that includes a range of arguments, factors or hypotheses. Opinions or conclusions should be presented clearly and supported by appropriate evidence. | AO3 |
| Evaluate | Make an appraisal by weighing up the strengths and limitations. | AO3 |
| Explain | Give a detailed account including reasons or causes. | AO3 |
| Justify | Give valid reasons or evidence to support an answer or conclusion. | AO3 |
| Predict | Give an expected result. | AO3 |
| Sketch | Represent by means of a diagram or graph (labelled as appropriate). The sketch should give a general idea of the required shape or relationship, and should include relevant features. | AO3 |
| Suggest | Propose a solution, hypothesis or other possible answer. | AO3 |
From the glossary of command terms in the IB Biology guide (first assessment 2025). The guide notes that other terms may also be used in questions.
IB markschemes are point-marked: each mark is a separate marking point, and the order of the points does not matter unless the markscheme says so. Learn the conventions below and you can mark your own practice answers the way an examiner would.
| You see | What it means |
|---|---|
| / (slash) | Alternative words: either word earns the mark, for example "vesicle / secretory granule / lysosome". |
| OR | Alternative answers: either answer earns the mark. |
| ALTERNATIVE 1, 2 … | Different markschemes for the whole answer, for when there is more than one valid way to answer it. |
| Underlined words | Essential for the mark. Leave the underlined word out and you lose the point, however good the rest is. |
| ( ) brackets | Words in brackets are not needed to earn the mark. |
| OWTTE | "Or words to that effect": an answer with the same meaning, or of equivalent significance, detail and validity, earns the mark. You do not have to use the markscheme's exact words. |
| ECF | "Error carried forward": if you make an error early and use it correctly later, you can still earn the later marks. The first error still loses its mark. |
| max | There are more marking points than marks, shown as for example "2 max". You can earn each mark in more than one way, but no more than the maximum. |
From the conventions key printed at the front of an IB Biology HL Paper 2 markscheme.
From the IB Biology guide (first assessment 2025). Always check the latest guidance with your teacher before the exam. Clock it with SCI is not affiliated with the IB.
