# A person is involved in a road accident and suffers damage to the retina of one eye. Explain how damage to the retina would affect the person's ability to see, referring to the roles of the rod cells and cone cells.

> Pearson Edexcel A-Level Biology A (9BI0) — 4.4 Vision and hearing · Explain · 5 marks

> The retina contains two types of photoreceptor cells: rod cells and cone cells. Rod cells are sensitive to low light intensities but cannot distinguish colour. Cone cells require bright light and are responsible for colour vision and fine detail.

## Mark scheme (5 marks)

1. The retina contains photoreceptor cells / rod cells and cone cells that detect light
2. Damage to the retina means light cannot be converted into electrical impulses / nerve impulses
3. Rod cells are responsible for vision in dim / low light conditions, so damage would impair ability to see in the dark / at night
4. Cone cells are responsible for colour vision and detecting fine detail, so damage would impair colour vision or ability to see detail clearly
5. Impulses would not be sent along the optic nerve to the brain, so no image is perceived / the brain cannot process the visual information

## Key terms

- [retina](https://www.gradenine.co.uk/glossary/retina)
- [rod cells](https://www.gradenine.co.uk/glossary/rod-cells)
- [cone cells](https://www.gradenine.co.uk/glossary/cone-cells)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" 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/a-person-is-involved-in-a-9b4232bd) · Published by Druglandscape Ltd.