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Command words tell you exactly what the examiner expects in your answer. Misreading or ignoring the command word is one of the most common reasons students lose marks in GCSE Biology. Two students can know the same science, but the one who responds correctly to the command word will score higher.
This lesson covers every command word used in Edexcel GCSE Biology, with worked examples showing how the same topic changes depending on the command word.
What it means: Write a short, factual answer. No explanation is needed.
How many marks: Usually 1 mark per point.
What to write: A word, phrase, or short sentence. Do not waste time explaining.
Exam tip: If the question says "state" or "name," keep it brief. Writing a long explanation wastes time and does not earn extra marks.
What it means: Give the precise scientific meaning of a term.
How many marks: Usually 1–2 marks.
What to write: A clear, concise definition using correct scientific language. Learn definitions from the specification.
Exam tip: Edexcel mark schemes have very specific definitions. Missing a key word (e.g., forgetting "partially permeable membrane" in the osmosis definition) can cost you a mark.
What it means: Say what happens or what you observe. Give an account of the main features, steps, or patterns — in a logical order.
How many marks: Usually 2–4 marks.
What to write: A step-by-step account or an account of what the data shows. Do not explain why — just say what happens.
"Describe the process of mitosis." → The cell copies its DNA. The chromosomes line up in the centre of the cell. The chromosomes are pulled to opposite ends of the cell. The cytoplasm divides. Two genetically identical daughter cells are produced.
"Describe the trend shown in the graph." → As temperature increases from 20°C to 40°C, the rate of enzyme activity increases. Above 40°C, the rate decreases rapidly.
Exam tip: When describing a trend in data, quote specific values from the graph or table. "The rate increases" is weaker than "The rate increases from 5 cm³/min at 20°C to 18 cm³/min at 40°C."
What it means: Say what happens and why. You must give reasons or mechanisms, not just describe.
How many marks: Usually 2–6 marks.
What to write: A linked chain of reasoning. For each point, state what happens and then explain why.
"Explain why the rate of enzyme activity decreases above 40°C." → Above the optimum temperature, the enzyme's active site changes shape (what happens). This is because the increased kinetic energy causes the bonds holding the tertiary structure to break (why). The substrate can no longer fit into the active site, so fewer enzyme-substrate complexes form (consequence). The enzyme is denatured.
"Explain how vaccination prevents disease." → A vaccine contains a dead or weakened form of the pathogen (what). This stimulates the immune system to produce specific antibodies (why/mechanism). Memory lymphocytes are produced (what happens next). If the person is exposed to the same pathogen in the future, the immune response is faster and stronger, preventing the disease from developing (consequence).
Exam tip: The most common mistake is describing when asked to explain. Always include the word "because" or "this means that" or "so" to show you are giving a reason, not just stating a fact.
What it means: Give similarities AND differences between two or more things.
How many marks: Usually 2–4 marks.
What to write: Explicit comparisons using linking words such as "both," "whereas," "however," "similarly," "unlike."
Exam tip: A common mistake is only giving differences. "Compare" means you must address both similarities and differences. Structure your answer so each point explicitly links the two things being compared.
What it means: Apply your scientific knowledge and understanding to a situation that is new or unfamiliar. There may not be one single correct answer.
How many marks: Usually 1–3 marks.
What to write: A reasonable scientific explanation or hypothesis based on the context given. Use the information in the question to guide your answer.
"A gardener notices that plants on the south side of a wall grow taller than those on the north side. Suggest why." → The south side of the wall receives more sunlight. More light energy is available for photosynthesis. The plants can produce more glucose for growth, so they grow taller.
"Suggest why the student's results were unreliable." → The student only repeated the experiment once, so anomalous results could not be identified. A larger sample size or more repeats would improve reliability.
Exam tip: "Suggest" questions are testing AO2 — your ability to apply knowledge. Do not panic if you have not seen the exact scenario before. Use the data and context provided, and apply what you know.
What it means: Use numbers to work out an answer. You must show your working.
How many marks: Usually 1–3 marks.
What to write: The mathematical steps leading to your answer. Write the formula, substitute the values, show the calculation, give the answer with correct units.
Exam tip: Even if you get the wrong final answer, you can still earn marks for your working. Always show the formula and the substitution. And never forget the units.
What it means: Give advantages AND disadvantages (or strengths and weaknesses), then reach a supported conclusion or judgement.
How many marks: Usually 4–6 marks.
What to write: A balanced argument with points for and against, followed by a conclusion that is supported by the evidence you have discussed.
Exam tip: The conclusion is essential. Without it, you cannot access the top marks. Your conclusion must be justified — say why you have reached that judgement based on the points you made.
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