# A doctor is reviewing the medical records of a patient who has been diagnosed with a tumour in the lung. The tumour began as a single cell in which a mutation occurred. Explain how a mutation in a single lung cell can lead to the formation of a malignant tumour that spreads to other parts of the body.

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

> Lung cancer is one of the most common cancers in the UK. It can develop over many years and is often not detected until the tumour is large. Some tumours remain localised, while others spread to distant organs such as the liver and brain.

## Mark scheme (5 marks)

1. A mutation causes a change in the DNA / genes of the cell
2. The mutation causes uncontrolled cell division / the cell divides repeatedly without stopping
3. This produces a mass of cells / a tumour forms
4. A malignant tumour can invade neighbouring tissues / the tumour cells break away from the original site
5. Tumour cells spread via the bloodstream / lymphatic system to other parts of the body and form secondary tumours (metastasis)

## Key terms

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

## 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-doctor-is-reviewing-the-medical-f9ae41e3) · Published by Druglandscape Ltd.