# Describe how a nerve impulse travels from a receptor to an effector in a simple reflex arc.

> WJEC GCSE Biology (Wales) — 2.5.1 The nervous system · Describe · 4 marks

## Mark scheme (4 marks)

1. The receptor detects a stimulus and generates a nerve impulse
2. The impulse travels along a sensory neurone towards the spinal cord / CNS
3. The impulse passes through a relay neurone in the spinal cord / CNS
4. The impulse travels along a motor neurone to an effector, which produces a response

## Key terms

- [receptor](https://www.gradenine.co.uk/glossary/receptor)
- [effector](https://www.gradenine.co.uk/glossary/effector)
- [reflex arc](https://www.gradenine.co.uk/glossary/reflex-arc)

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-a-nerve-impulse-travels-24041998) · Published by Druglandscape Ltd.