# Describe how the pupil of the eye responds to a sudden increase in light intensity, naming the muscles involved and explaining the function of this response.

> Cambridge International IGCSE Biology (0610) — 14.2 Sense organs · Describe · 4 marks

## Mark scheme (4 marks)

1. Circular muscles contract
2. Radial muscles relax
3. The pupil constricts / becomes smaller, so less light enters the eye
4. This prevents damage to the eye / retina from bright light

## Key terms

- [pupil](https://www.gradenine.co.uk/glossary/pupil)

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-the-pupil-of-the-6a67e4dd) · Published by Druglandscape Ltd.