How much should I write for each IB Biology command term?

The command term determines the kind of depth required, while the mark allocation helps indicate the likely breadth. A state response is normally brief, whereas an explain response needs connected reasons or causal stages. For discuss or evaluate, several developed points and a supported judgment may be necessary. There is no official universal rule that one mark equals one sentence, so focus on distinct, relevant ideas rather than sentence counting. Stop when you have fulfilled the command, addressed the complete scope, and supplied enough valid points for the available marks.

What is the difference between outline, describe, and explain in IB Biology?

Outline means giving a brief account or summary containing the main features. Describe requires a detailed account of what happens, what something looks like, or what pattern is present. Explain goes further by including reasons, causes, or mechanisms. For enzyme denaturation, an outline might state that activity falls above the optimum temperature, while a description would detail the observed change across temperatures. An explanation would connect increased molecular motion and disrupted bonds to alteration of the active site and reduced substrate binding.

Does compare mean similarities and differences in IB Biology?

In the current IB Biology guide, compare means giving an account of similarities while referring to both or all items throughout. Compare and contrast explicitly requires both similarities and differences. This distinction is worth learning because informal classroom usage of “compare” sometimes includes differences. Use paired statements so every point directly links the items, rather than writing separate descriptions. Always follow the exact command term printed in the examination question and the definition in the current subject guide.

Do I need a conclusion for discuss and evaluate questions?

A discuss response should present a considered and balanced review, with opinions or conclusions supported by appropriate evidence. An evaluate response should weigh strengths and limitations, making an appraisal rather than merely listing them. A clear concluding judgment is therefore highly advisable because it demonstrates that the evidence has been weighed. The conclusion should answer the precise question and may be qualified when the evidence is limited. Avoid introducing entirely new biological points in the final sentence because they should have been developed in the main response.

Can bullet points be used in IB Biology exam answers?

Bullet points can communicate concise, separate ideas effectively, especially for commands such as list, state, or outline. They can also work in longer answers if each bullet contains sufficient biological detail and logical development. However, causal explanations and evaluations often benefit from connected prose because relationships between ideas must be explicit. The important issue is not the visual format but whether the response fulfills the command term clearly. Do not reduce an explanation to isolated keywords, since examiners cannot award reasoning that has not been communicated.

What is the best way to revise IB Biology command terms?

First learn the official meanings, then apply each term to real or exam-style Biology questions. Group similar prompts, such as outline, describe, and explain, and answer the same topic at each level of depth. Compare every attempt with a markscheme or worked solution, noting whether lost marks came from weak knowledge or failure to follow the command. Watching per-question video solutions is particularly useful because it shows how reasoning is built and how long a complete response needs to be. Finish by using timed Questionbank or mock-exam sets and asking Jojo AI to identify missing causal links, comparisons, evidence, or judgments.

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IB Biology Command Terms Explained With Examples

RevisionDojo Team

•Last updated: 5 Aug 2026•14 min read

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IB Biology Command Terms Explained With Examples

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IB Biology Command Terms Explained With Examples

RevisionDojo Team

•Last updated: 5 Aug 2026•14 min read

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IB Biology command terms are the instructional verbs in exam questions, such as state, outline, explain, and evaluate. They tell you what intellectual task to perform and how much depth your response requires. Knowing the biology is not enough if your answer does not perform the task specified by the command term.

The current IB Biology guide, for first assessment in 2025, organizes command terms broadly by assessment objective. Some require concise recall, others require application, and the most demanding require analysis, evaluation, or synthesis. The definitions below follow the current guide, while the response strategies are practical advice rather than fixed IB rules.

Why IB Biology command terms matter

A command term determines what can earn credit. If a question says state, adding a lengthy mechanism wastes time. If it says explain, merely naming the outcome is incomplete because the answer needs reasons, causes, or a mechanism.

Always read three parts of a question before writing:

Command term: What must you do?
Biological content: What topic must you address?
Scope and context: Does the question specify an organism, data set, condition, or number of examples?

The mark allocation can help you judge breadth, but there is no universal rule that one mark always equals one sentence. A concise sentence may contain several relevant ideas, while a long sentence may contain none. Treat the available marks as a guide to the number of distinct, developed points required.

Essential recall and representation terms

These terms commonly ask for precise knowledge or a correctly presented visual response.

Command term	What the IB expects	Biology example and suitable response
Define	Give the precise meaning of a word, phrase, concept, or physical quantity.	Define an allele. An allele is one of two or more alternative forms of a gene.
State	Give a specific name, value, or brief answer without explanation or calculation.	State the site of translation. Ribosomes.
List	Give a sequence of brief answers with no explanation.	List three components of a nucleotide. Phosphate group, pentose sugar, nitrogenous base.
Identify	Provide an answer from several possibilities.	Identify the organelle shown. Mitochondrion.
Label	Add labels to a diagram.	Place accurate names beside the appropriate structures, using clear label lines.
Draw	Produce a labelled, accurate diagram or graph using a pencil.	A cell drawing should use clear lines, accurate proportions, labels, and a ruler for straight lines.
Measure	Obtain a value for a quantity.	Read the specimen length from a scale and include the appropriate unit.

A definition is not the same as an example. Defining osmosis by saying “water entering a plant cell” gives an instance, but not its precise meaning. A complete definition must establish the net movement of water through a selectively permeable membrane down a water-potential gradient.

Application and detailed-account terms

These terms require more than recalling an isolated fact. You may need to apply knowledge, report detail, distinguish concepts, or summarize a process.

Command term	Required depth	Effective approach
Annotate	Add brief notes to a diagram or graph.	Combine labels with short functional or explanatory notes.
Apply	Use an idea, equation, principle, theory, or law in relation to a problem.	Select relevant biological knowledge and use it in the unfamiliar context provided.
Calculate	Obtain a numerical answer while showing relevant working stages.	Write the formula, substitute values, calculate, and give units where applicable.
Describe	Give a detailed account.	Report what happens, what is present, or what pattern the data show. Include sequence and values where relevant.
Distinguish	Make differences between two or more items clear.	Use paired contrasts such as “X does..., whereas Y does....”
Estimate	Obtain an approximate value.	Read or infer a reasonable value and show how it was obtained when useful.
Outline	Give a brief account or summary.	Include the principal stages or features without developing every mechanism.

Outline, describe, and explain compared

These three terms often cause avoidable errors. Consider a question about ventilation:

Outline ventilation: Air moves into the lungs during inhalation and out during exhalation.
Describe inhalation: The diaphragm contracts and flattens, the external intercostal muscles contract, the rib cage moves up and out, and thoracic volume increases.
Explain inhalation: Contraction of the diaphragm and external intercostal muscles increases thoracic volume. This lowers pressure inside the lungs below atmospheric pressure, so air moves into the lungs down the pressure gradient.

An outline selects the main features. A description supplies a detailed account of what occurs. An explanation establishes why or how it occurs through connected causal reasoning.

Higher-order analytical command terms

These terms often appear in data-based, experimental, and extended-response questions. They require conclusions, relationships, evidence, or judgments rather than unconnected factual recall.

Command term	What a successful answer does
Analyse	Breaks information down to reveal essential elements, patterns, or relationships.
Comment	Gives a judgment based on a statement or calculated result.
Compare	Gives similarities between items, referring to both throughout.
Compare and contrast	Gives both similarities and differences, referring to all items throughout.
Construct	Displays information in a diagrammatic or logical form.
Deduce	Reaches a conclusion from information supplied in the question.
Design	Produces a plan, simulation, or model.
Determine	Obtains the only possible answer.
Discuss	Offers a considered, balanced review of arguments, factors, or hypotheses, supported by evidence.
Evaluate	Makes an appraisal by weighing strengths and limitations.
Explain	Gives a detailed account including reasons or causes.
Justify	Provides valid reasons or evidence supporting an answer or conclusion.
Predict	Gives an expected result.
Sketch	Shows the general shape or relationship in a diagram or graph, including relevant features.
Suggest	Proposes a possible solution, hypothesis, or answer.

A frequently misunderstood point is that the current Biology guide defines compare in terms of similarities. If the question says compare and contrast, both similarities and differences are needed. In either case, write paired points that refer explicitly to both items rather than completing two disconnected mini-essays.

Explain, discuss, and evaluate compared

Suppose a question concerns biological control of an invasive species:

Explain asks for the mechanism, such as how a predator reduces the invasive population and changes competition.
Discuss asks for a balanced review of relevant factors, potentially including effectiveness, effects on non-target organisms, ecological uncertainty, and alternatives.
Evaluate asks you to appraise the approach by weighing strengths against limitations and reaching a supported judgment.

An evaluation should not be a generic list of advantages and disadvantages. State the criteria being used, connect each judgment to evidence or biological reasoning, and finish with a qualified conclusion. For example, biological control may be effective and require little repeated application, but it is difficult to reverse and may threaten non-target species, so its suitability depends on rigorous host-specificity testing.

Command terms in data-based questions

Data questions test both reading accuracy and biological interpretation. Match your response to the verb:

Describe: Quote the overall trend, relevant values, maxima or minima, and anomalies. Do not explain the mechanism unless asked.
Analyse: Break the data into meaningful patterns, compare conditions, and identify relationships supported by values.
Calculate: Show working and retain appropriate units.
Deduce: Derive a conclusion from the supplied evidence rather than simply recalling a textbook fact.
Suggest: Offer a biologically plausible answer. More than one response may be defensible, but it must fit the evidence.
Evaluate: Consider reliability, uncertainty, sample size, controls, variation, and whether the evidence supports the stated conclusion.

If instructed to use the data, numerical evidence matters. “Enzyme activity increased” is less informative than “activity increased from 12 to 29 arbitrary units between 20°C and 40°C.” Do not claim causation merely because two variables are correlated.

Common command-term mistakes

Explaining when asked to state: This consumes time without answering additional demands.
Describing when asked to explain: Reporting that enzyme activity falls does not explain denaturation or changes to the active site.
Giving examples instead of definitions: Examples illustrate meaning but rarely establish it precisely.
Writing separate accounts for comparisons: Use linked sentences containing both items.
Treating discuss and evaluate as synonyms: Discussion reviews a range of arguments or factors; evaluation explicitly appraises strengths and limitations.
Ignoring the question context: A correct explanation about respiration may still be irrelevant if the question asks specifically about anaerobic respiration in yeast.
Forgetting evidence: Judgments and conclusions should be supported by data or biological reasoning.

How to internalise command terms efficiently

Memorizing definitions is useful, but the fastest route to reliable exam technique is seeing many questions worked through. You need to observe how a short state response differs from a causal explain response and how an evaluate answer weighs evidence before reaching a judgment.

Use this practice cycle:

Circle the command term and underline the biological scope.
Translate the term into a task, such as “give causes” or “weigh strengths and limitations.”
Plan distinct points using the mark allocation as a guide.
Answer without unnecessary background information.
Compare your response with the markscheme or worked solution.
Rewrite the answer, correcting both content and command-term depth.

The IB Biology Questionbank allows targeted exam-style practice, while the Biology video library helps you watch questions and concepts worked through. Use the available per-question video explanations and worked solutions to notice exactly how each response matches its command term. Jojo AI can then identify when an answer contains correct biology but lacks the required reasoning, comparison, or judgment.

For knowledge gaps revealed by practice, return to the IB Biology resource hub or use Biology flashcards to strengthen precise definitions. Once individual terms feel secure, complete Biology predicted papers under timed conditions to practise switching between different response depths.

Conclusion

IB Biology command terms tell you both what to do and how deeply to do it. State and list require brevity, describe requires detail, explain requires causal reasoning, and discuss or evaluate requires supported higher-order judgment. Read the command term alongside the question scope and mark allocation, then provide only the type of response requested.

Repeated exam-question practice is more effective than memorizing a glossary alone. RevisionDojo’s Biology Questionbank, per-question video solutions, and Jojo AI feedback can help you connect each official definition to the form of answer that earns credit.

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