How the essay is marked
The DBE Life Sciences papers end with an essay worth 20 marks: 17 for content and 3 for synthesis.
| Synthesis mark | What it means |
|---|
| Relevance (R) | All the information is about the question; nothing irrelevant is included. |
| Logical sequence (L) | Ideas are in a logical order — for a process, in the order the steps happen. |
| Comprehensive (C) | All parts of the question are answered, with enough correct facts in each part. |
- Content marks are given for correct biological facts, one mark per fact (up to the maximum for each part).
- Write in full sentences and paragraphs — no tables, flow charts or diagrams (these earn no marks in the essay).
- Most essays have two or three parts, e.g. “Describe meiosis I and explain how it leads to genetic variation.”
Planning in five minutes
- Underline the instruction words (describe, explain, compare) and number the parts of the question.
- Brainstorm facts for each part — aim for more facts than the marks available (about 10 for an 8-mark part).
- Order them logically: a process from start to finish; a structure from outside to inside.
- Write one paragraph per part, using the key terms. No introduction or conclusion is needed.
- Check that every part is answered (for the C mark).
✏️ Sample plan: “Describe how the ear maintains balance and explain how the body responds to a drop in blood glucose.”
1Part 1 — balance (~8 facts): semicircular canals at right angles; contain endolymph; cristae at the base (ampulla); head movement moves endolymph, which bends the cupula/hair cells; maculae in the utriculus and sacculus detect head position (gravity); impulses travel via the auditory nerve to the cerebellum; cerebellum coordinates muscles to restore balance.
2Part 2 — glucose (~9 facts): low blood glucose detected by the pancreas (islets of Langerhans); α-cells secrete glucagon; carried by the blood to the liver; glycogen converted to glucose; glucose released into the blood; blood glucose rises to normal; negative feedback switches off glucagon secretion.
Source-based questions
IEB papers in particular give long extracts, case studies, tables and graphs, and then ask you to use the source and your own knowledge. DBE papers do the same in shorter questions.
- Read the question first, then the source, so you know what to look for.
- “According to the extract …” — answer only from the source; quote or paraphrase the relevant line.
- “Use your own knowledge …” — bring in theory the source does not give (e.g. the mechanism of natural selection).
- “Evaluate” / “Discuss” — give points for and against, then a supported judgement.
- Link source to theory: “The extract states that … This is because …”
- Match the length to the marks: a 4-mark “explain” needs about four linked points.
Case-study tip (human impact, evolution, genetics): identify the problem, the cause, the consequence and a solution. Use the numbers in the source to support every claim.
Instruction words
| Word | What to do |
|---|
| Name / State / List | Give the term or fact only — no explanation |
| Describe | Say what happens or what something looks like, in order |
| Explain | Give reasons — use “because”, “so”, “which leads to” |
| Compare / Tabulate differences | Give matching points for both (a table is allowed here, but not in the essay) |
| Suggest | Apply your knowledge to a new situation; more than one answer may be accepted |
| Evaluate | Weigh up evidence and reach a judgement |