# "Explain" questions — WJEC A-Level Biology (Wales)

> 74 questions · biology

## How to answer

WHAT + WHY. Every point paired with a because. Structure: X happens because Y. This causes Z because … Assessment Objective: AO2. Every "explain" answer on this spec is marked against exactly this pattern.

## Sample questions

1. [Explain why it is difficult for scientists to research the structure and functions of the human brain.](https://www.gradenine.co.uk/q/explain-why-it-is-difficult-for-0011e027)
2. [A person has been exercising vigorously in hot weather and has not drunk any water for several hours. Explain what happe…](https://www.gradenine.co.uk/q/a-person-has-been-exercising-vigorously-0083cde2)
3. [A patient is diagnosed with cancer after a routine screening. Explain how cancer develops in the body and describe two c…](https://www.gradenine.co.uk/q/a-patient-is-diagnosed-with-cancer-047456a6)
4. [The cell membrane is described as selectively permeable and controls the movement of substances into and out of the cell…](https://www.gradenine.co.uk/q/the-cell-membrane-is-described-as-0af01602)
5. [Explain how temperature affects the rate of an enzyme-controlled reaction, including what happens both below and above t…](https://www.gradenine.co.uk/q/explain-how-temperature-affects-the-rate-11d723f7)
6. [Explain how a change in pH away from an enzyme's optimum affects the rate of an enzyme-controlled reaction.](https://www.gradenine.co.uk/q/explain-how-a-change-in-ph-12fa1ec9)
7. [Explain how the structure of a synapse allows a nerve impulse to pass from one neurone to the next.](https://www.gradenine.co.uk/q/explain-how-the-structure-of-a-1308b3f9)
8. [Explain how a rise in temperature above an enzyme's optimum affects the rate of reaction. In your answer, refer to the a…](https://www.gradenine.co.uk/q/explain-how-a-rise-in-temperature-1a2a1f63)

## Related

- [WJEC A-Level Biology (Wales) revision notes](https://www.gradenine.co.uk/learn/wjec-a-level-biology-wales)
- [WJEC A-Level Biology (Wales) past papers](https://www.gradenine.co.uk/past-papers/wjec-a-level-biology-wales)
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