Answering 6-Mark Extended Response Questions

The 6-mark extended response questions are the highest-tariff questions on both Paper 1 and Paper 2. They are marked differently from other questions — using a levels-based mark scheme rather than a point-by-point mark scheme.

This means that the quality, organisation, and coherence of your answer matters just as much as the science content. A disorganised answer with correct points may score lower than a well-structured answer with the same content.

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How 6-Mark Questions Are Marked

Examiners use a three-level mark scheme:

Level	Marks	Description
Level 3	5–6 marks	A detailed, coherent answer that demonstrates comprehensive knowledge and understanding. Scientific terminology is used correctly throughout. The answer is well-organised with a clear, logical structure.
Level 2	3–4 marks	An answer that demonstrates reasonable knowledge and understanding. Some scientific terminology is used. The answer has some structure but may lack coherence in places.
Level 1	1–2 marks	An answer that demonstrates limited knowledge. Simple statements are made with little or no linking. Scientific terminology may be absent or used incorrectly.
No marks	0 marks	No relevant content.

Exam tip: To reach Level 3, your answer needs three things: correct science, scientific terminology, and logical organisation. Missing any one of these limits you to Level 2 at best.

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The Importance of Quality of Written Communication

6-mark questions assess Quality of Written Communication (QWC). This means:

• Spelling of scientific terms should be correct (or at least recognisable)
• Grammar should allow your meaning to be understood
• Scientific vocabulary should be used accurately and appropriately
• Structure should be logical — your answer should flow from one point to the next

You do not need perfect English, but your writing must be clear enough for the examiner to follow your reasoning.

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The Structure of a Top-Level 6-Mark Answer

graph TD
    A["Read the question carefully"] --> B["Identify command word and topic"]
    B --> C["Plan 5-7 key points in order"]
    C --> D["Write opening sentence with context"]
    D --> E["Present points in logical sequence"]
    E --> F["Use scientific terminology throughout"]
    F --> G["Link points with connectives: therefore, because, as a result"]
    G --> H["Add conclusion if evaluate or discuss"]
    H --> I["Check: Have I answered the actual question?"]

    style A fill:#3498db,color:#fff
    style C fill:#e67e22,color:#fff
    style F fill:#2ecc71,color:#fff
    style H fill:#9b59b6,color:#fff
    style I fill:#e74c3c,color:#fff

Step-by-Step Strategy for 6-Mark Questions

Step 1: Read the Question Carefully (30 seconds)

• Underline the command word (Describe? Explain? Evaluate? Discuss?)
• Underline the key topic or focus
• Check if the question asks about a specific context or gives you data to use

Step 2: Plan Your Answer (1–2 minutes)

This is the most important step. On the exam paper (in the margin or space provided), quickly jot down:

• 5–7 key points you want to make
• The order you will make them in
• Any scientific terms you must include

Step 3: Write Your Answer (4–5 minutes)

• Write in paragraphs (not bullet points)
• Start with an introduction or topic sentence
• Present points in a logical sequence (e.g., chronological order for a process, or cause → effect → consequence)
• Use scientific terminology throughout
• Link points together with connectives: "this causes," "as a result," "therefore," "because," "consequently"
• End with a conclusion if appropriate (especially for "evaluate" or "discuss" questions)

Step 4: Check Your Answer (30 seconds)

• Have you addressed the command word?
• Have you used scientific terms?
• Does your answer make logical sense?
• Have you answered the actual question asked?

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Worked Example 1: Describe

Question: "Describe how the body responds to an increase in blood glucose level after a meal." (6 marks)

Plan:

• Meal → blood glucose rises
• Detected by pancreas
• Insulin released
• Insulin → cells take up glucose
• Glucose → glycogen in liver
• Blood glucose returns to normal
• Negative feedback

Model Answer:

After eating a carbohydrate-rich meal, glucose is absorbed into the blood from the small intestine, causing blood glucose concentration to rise above the normal level.

This increase is detected by the pancreas, which responds by releasing the hormone insulin into the bloodstream. Insulin is produced by specialised cells in the islets of Langerhans within the pancreas.

Insulin travels in the blood to its target organs — the liver and muscle cells. It causes cells to take up more glucose from the blood. In the liver, excess glucose is converted into glycogen for storage. This process is called glycogenesis.

As a result, the blood glucose concentration decreases and returns to its normal set point. This is an example of negative feedback — the response (insulin release) reverses the change (high blood glucose) to restore the normal condition.

If blood glucose continues to be too high, more insulin is released. If it drops too low, the pancreas releases glucagon instead, which causes glycogen to be converted back into glucose.

This answer would achieve Level 3 (5–6 marks) because it is detailed, uses correct scientific terminology throughout, and presents the process in a clear, logical sequence.

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Worked Example 2: Explain

Question: "Explain how natural selection can lead to the evolution of a new species." (6 marks)

Plan:

• Variation in population
• Environmental change / isolation
• Selection pressure
• Survival and reproduction
• Allele frequency changes
• Speciation through isolation

Model Answer:

Within a population, individuals show genetic variation due to mutations and sexual reproduction. This variation means some individuals have characteristics that are better suited to the environment than others.

If a population becomes geographically isolated — for example, by a river or mountain range separating two groups — the two groups experience different environmental conditions and therefore different selection pressures.

In each group, individuals with characteristics that give a selective advantage in their specific environment are more likely to survive and reproduce. They pass on the alleles for these advantageous traits to their offspring. Over time, the frequency of these beneficial alleles increases in the population through natural selection.

Because the two isolated groups are subjected to different selection pressures, they evolve in different directions. Over many generations, the genetic differences between the two groups accumulate to the point where individuals from the two groups can no longer interbreed to produce fertile offspring.

At this point, the two groups are classified as separate species. This process is called speciation. The geographic isolation prevented gene flow between the populations, allowing them to diverge genetically.

This answer would achieve Level 3 because it explains the mechanism step by step, uses key terminology (genetic variation, alleles, selection pressure, gene flow, speciation), and presents a coherent, logical argument.

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Worked Example 3: Evaluate

Question: "Evaluate the use of monoclonal antibodies in treating cancer." (6 marks)