# A student is reading a book and then looks up to watch a bird flying in the distance. Describe how the structure of the eye allows a clear image to be formed on the retina in each situation, and name the part of the retina that produces the clearest image.

> Eduqas A-Level Biology — 4.6 The nervous system · Describe · 5 marks

> When focusing on a nearby object such as a book, and then a distant object such as a bird in the sky, different structures within the eye must adjust to ensure that a clear image is produced.

## Mark scheme (5 marks)

1. The cornea refracts light as it enters the eye
2. The lens changes shape to focus the image onto the retina
3. For a nearby object (the book) the lens becomes thicker / more curved to refract light more strongly
4. For a distant object (the bird) the lens becomes thinner / less curved / flatter to refract light less strongly
5. The fovea produces the clearest image because it contains a high concentration of cone cells

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-reading-a-book-c2cddeb9) · Published by Druglandscape Ltd.