SPM Biology command words explained
Command words tell you exactly what an answer needs. "State" wants a fact; "explain" wants a reason; "compare" wants both similarities and differences. Answering the wrong command loses marks even when the biology is right.
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Why command words matter
Every Paper 2 question begins with a command word that sets the type of answer expected. Marks are awarded for matching that command, so a long explanation for a question that only says "state" wastes time, and a one-word answer to "explain" leaves marks on the table.
The common command words
| Command word | What the answer needs |
|---|---|
| State / Name | A short fact or term, no explanation |
| Describe | What happens or what something looks like, in order |
| Explain | A reason, use "because" or "so that" |
| Compare | Both similarities and differences, point by point |
| Suggest | A sensible idea applied to a new situation |
| Calculate | A worked number with the correct unit |
| Define | The exact meaning of a term |
How to use them
- Underline the command word before you start writing.
- Match the length of your answer to the command, "state" is one line, "explain" needs a reason.
- For "compare", make sure each point mentions both things being compared.
- For "explain", always give the cause, not just the observation.
More command words you will meet
Beyond the core words, Paper 2 uses a second set that tells you the form your answer should take rather than the type of reasoning. Reading these correctly saves you from writing an essay where a single word is wanted, or a word where working is wanted.
| Command word | What the answer needs |
|---|---|
| List | A set of short items one after another, with no explanation |
| Identify | Pick out and name the correct item from those given |
| Label | Write the correct names on the parts of a diagram |
| Complete | Fill in the missing parts of a table, diagram or sentence |
| Draw | A clear line drawing, correct in shape and proportion |
| Predict | State what will happen, based on a pattern or principle |
| Give a reason | One cause, written like a short explain answer |
| Deduce | Work out the answer using the information provided |
Match your answer to the marks
The command word tells you the kind of answer; the mark in brackets tells you how much of it to write. A question that says "explain" and is worth four marks wants four linked ideas, not one reason repeated, while a "state" worth one mark wants a single clean fact.
A safe habit is to count the marks, then plan that many distinct points before you write. For an "explain" this usually means pairing each observation with its cause; for a "compare" it means making sure each point names both things being compared.
Worked examples for the key commands
State. 'State one product of photosynthesis.' A complete answer is simply glucose (or oxygen); no explanation is needed or rewarded.
Describe. 'Describe the change in the pupil in bright light.' Answer: the radial muscles relax and the circular muscles contract, so the pupil constricts.
Explain. 'Explain why the pupil constricts in bright light.' Answer: to reduce the amount of light entering the eye so that the retina is protected from damage.
Compare. 'Compare arteries and veins.' Answer point by point: arteries have thick elastic walls whereas veins have thin walls; arteries carry blood away from the heart whereas veins return it to the heart; veins have valves whereas arteries do not.
Suggest. 'Suggest why a plant kept in the dark for a week has no starch in its leaves.' Answer: with no light there is no photosynthesis, so no glucose is made to be stored as starch.
Command words in the practical paper
Paper 3 uses its own set of instructions built on the science process skills. "State the hypothesis" wants a testable link between the manipulated and responding variables; "state the variables" wants you to name the manipulated, responding and controlled (fixed) variables separately.
"Tabulate your results" wants a table with correct headings and units, "plot a graph" wants axes labelled with units and points joined suitably, and "deduce" or "make an inference" wants a conclusion drawn from the results you recorded, not from memory.
State, name and define are not the same
Three short commands look alike but want different things. "Name" or "state" wants the term or the fact in the fewest words.
"Define" wants the full meaning of a term written as a complete sentence, a definition of osmosis, for example, must include the phrases 'net movement of water', 'partially permeable membrane' and the direction of movement.
Because a definition carries set phrases that each earn a mark, learn the standard wording rather than paraphrasing it. A name answer, by contrast, is marked right or wrong on the single term, so a spelling that changes the meaning can cost the mark.
Common ways command words are misused
Source:SRC-FORMAT
Frequently asked questions
What is the difference between describe and explain?
How do I answer a "compare" question?
How do I know how many points to write?
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