SPM Biology Paper 2 Section B: restricted essays
Section B (20 marks, 2 questions (answer 1)) is a restricted-response essay built from sub-parts, answer each sub-part fully, in order, using precise biological terms.
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What Section B asks for
Section B offers 2 questions (answer 1), worth Section B: 20 marks. Despite being called an "essay", it is a restricted-response question: it is broken into sub-parts, each with its own command word and mark allocation, rather than a single free-flowing piece of writing.
Because you choose which question to answer, the first decision, which one to attempt, matters as much as the writing itself.
Structuring your answer
- Read both questions fully before choosing; pick the one whose sub-parts you can all answer, not just the one with the more familiar title.
- Answer the sub-parts in the order given, and label each part of your answer to match, (a), (b)(i) and so on.
- Underline the command word in each sub-part and answer exactly that: a fact for "state", a reason for "explain", steps in order for "describe".
- Include a labelled diagram wherever the sub-part deals with structure or a process, a clear diagram can earn marks quickly and support your written answer.
- Use precise biological terms throughout; a near-right word can cost the mark even when the idea is correct.
Command words in a Section B essay
A Section B question spreads a set of command words across its sub-parts, so the same essay can ask you to state, describe and explain in turn. Answer the command word in front of you rather than writing everything you know about the topic.
| Command word | What a Section B sub-part expects |
|---|---|
| State / Name | A term or fact only, no explanation needed in this sub-part |
| Describe | The stages of a structure or process, in order |
| Explain | Why or how something happens, the reason behind it |
| Compare | A stated similarity or difference that covers both things |
| Suggest | An applied answer for an unfamiliar case, using sound biology |
Using diagrams to earn marks quickly
A labelled diagram can earn marks faster than a paragraph, and it supports a written explanation the marker can follow at a glance. Draw one wherever a sub-part deals with a structure or the stages of a process.
Draw in pencil so you can correct it, use a ruler for label lines, and make each line touch the exact part it names. Label with the correct biological term, spelt correctly, because a mislabelled part earns nothing even when the drawing is neat.
Keep the diagram large enough to label clearly rather than crowding it into a corner.
A worked Section B outline
Question. The diagram shows an alveolus and the blood capillary around it. (a) Name the process by which oxygen moves from the alveolus into the blood. [1] (b) State two features of the alveolus that make gas exchange efficient. [2] (c) Explain how each feature you named in (b) speeds up gas exchange. [4] (d) Describe what happens to the oxygen after it enters the red blood cell. [3]
Model answer. (a) Diffusion. (b) A large surface area and a thin wall one cell thick; a moist surface; a rich blood supply.
(Any two.) (c) A large surface area gives more room for oxygen to diffuse across at once; a wall one cell thick gives a short diffusion distance; a rich blood supply carries oxygen away and keeps a steep concentration gradient, so diffusion stays fast. (d) Oxygen combines with haemoglobin in the red blood cell to form oxyhaemoglobin; the blood carries it through the arteries to respiring tissues, where oxyhaemoglobin releases the oxygen for aerobic respiration.
What a strong Section B answer looks like
| Weaker answer | Stronger answer |
|---|---|
| One long paragraph covering everything you remember | Separate, labelled answers for each sub-part, in order |
| General description with no named terms | Precise biological terms used for each structure or step |
| Diagram left out or unlabelled | A labelled diagram included where the sub-part calls for one |
Common pitfalls
Source:SRC-FORMAT
Frequently asked questions
How is Section B marked if it is called an essay?
How do I choose between the two Section B questions?
What command words appear in Section B?
How much of a Section B answer should be diagrams?
Do I need a diagram in a Section B answer?
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