# A student is studying how the eye and ear detect different stimuli. Describe how light entering the eye is focused onto the retina, and explain what happens after the retina detects the light stimulus.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 4.4 Vision and hearing · Describe and Explain · 5 marks

> The human eye and ear are both sense organs. The eye detects light stimuli, while the ear detects sound stimuli. Both organs send information to the brain via nerve impulses.

## Mark scheme (5 marks)

1. Light passes through the cornea, which refracts (bends) the light
2. The lens also refracts light and focuses it onto the retina
3. The retina contains receptor cells (rod and/or cone cells) that are sensitive to light
4. The receptor cells generate / send nerve impulses
5. Nerve impulses travel along the optic nerve to the brain, where they are interpreted as vision

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-student-is-studying-how-the-adc67736) · Published by Druglandscape Ltd.