# A scientist is studying skin cancer in patients who have been exposed to high levels of ultraviolet (UV) radiation from the sun. The scientist finds that the skin cells of these patients divide in an uncontrolled way, forming a tumour. Describe how exposure to UV radiation can lead to the formation of a tumour in skin cells.

> OCR A-Level Biology B — Advancing Biology (H422) — 3.2 Disease, mutation and cancer · Describe · 5 marks

> Ultraviolet (UV) radiation from the sun is a known mutagen that can damage the DNA of skin cells. Studies show that people with prolonged exposure to UV radiation have a significantly higher risk of developing skin cancer compared to those who limit their sun exposure.

## Mark scheme (5 marks)

1. UV radiation is a mutagen that causes a mutation in the DNA of a skin cell
2. The mutation affects the gene(s) that control cell division
3. The mutated cell divides uncontrollably / does not respond to signals to stop dividing
4. Repeated uncontrolled cell division produces a mass of abnormal cells / a tumour forms
5. A malignant tumour can spread to other parts of the body / metastasise, or: benign tumours remain contained / do not invade other tissues

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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-scientist-is-studying-skin-cancer-b1538804) · Published by Druglandscape Ltd.