# A student is reading about cancer in a biology textbook. The textbook explains that some cancers are caused by mutations in genes that normally control cell division. Explain how mutations in these genes can cause cancer, and describe one difference between a benign tumour and a malignant tumour.

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

> Cancer is one of the leading causes of death worldwide. Cells in the body normally divide in a controlled way. When certain genes that regulate cell division undergo mutation, this control can be lost, potentially leading to the formation of a tumour.

## Mark scheme (5 marks)

1. A mutation is a change in the DNA (base sequence / genetic code) of a cell
2. The mutation affects genes that control cell division, so the cell divides uncontrollably / out of control
3. This uncontrolled cell division leads to the formation of a tumour (a mass of abnormal cells)
4. A benign tumour does not spread / invade other tissues — it stays localised / contained in one place
5. A malignant tumour can spread (metastasise) to other parts of the body / invade surrounding tissues

## Key terms

- [mutation](https://www.gradenine.co.uk/glossary/mutation)
- [tumour](https://www.gradenine.co.uk/glossary/tumour)
- [benign tumour](https://www.gradenine.co.uk/glossary/benign-tumour)
- [malignant tumour](https://www.gradenine.co.uk/glossary/malignant-tumour)
- [cell division](https://www.gradenine.co.uk/glossary/cell-division)

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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-student-is-reading-about-cancer-3882df81) · Published by Druglandscape Ltd.