# Describe the distribution of rod cells and cone cells in the retina, and explain how this distribution affects a person's ability to see in dim light and to detect colour.

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

## Mark scheme (4 marks)

1. Rod cells are distributed at the periphery of the retina / evenly distributed around the retina (and are absent at the fovea)
2. Cone cells are concentrated at the fovea (in the centre of the retina)
3. Rod cells are sensitive to low light intensities, so they allow vision in dim light (monochromatic / black and white vision)
4. Cone cells are sensitive to bright light and detect different colours / there are three types of cone cell each sensitive to a different colour (red, green, blue), so colour vision requires bright light

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-distribution-of-rod-cells-5b517017) · Published by Druglandscape Ltd.