# A group of researchers investigated the link between exposure to certain chemicals and the development of cancer in factory workers. Some workers developed tumours that were classified as benign, whilst others developed malignant tumours. Describe the differences between benign and malignant tumours, and explain why malignant tumours are more dangerous to health.

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

> Factory workers exposed to mutagenic chemicals over many years were found to have higher rates of tumour development than the general population. Medical examination revealed that some workers had benign tumours whilst others had malignant tumours.

## Mark scheme (5 marks)

1. Benign tumours do not invade surrounding tissue / stay in one place / are contained
2. Malignant tumours invade and destroy surrounding tissue / spread into neighbouring tissues
3. Malignant tumour cells can break away from the original tumour and travel through the bloodstream / lymphatic system
4. Malignant cells form secondary tumours (metastases) in other parts of the body
5. This makes malignant tumours harder to treat / more life-threatening because multiple organs can be affected

## Key terms

- [malignant tumour](https://www.gradenine.co.uk/glossary/malignant-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-group-of-researchers-investigated-the-8deb773d) · Published by Druglandscape Ltd.