# Describe how the body's physical defences help to prevent pathogens from entering the body.

> OCR GCSE Biology A: Gateway Science (J247) — B6.3 Monitoring and maintaining health · Describe · 4 marks

> A student learns that the human body has several layers of defence against communicable diseases. The first line of defence involves physical and chemical barriers that stop pathogens before they can cause infection.

## Mark scheme (4 marks)

1. The skin acts as a physical barrier to pathogens
2. Mucus in the airways traps pathogens / airborne pathogens
3. Cilia beat / waft to move mucus (and trapped pathogens) away from the lungs / up towards the throat
4. Stomach acid / hydrochloric acid kills pathogens that are swallowed

## Key terms

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

## Related

- [Revision notes for OCR GCSE Biology A: Gateway Science (J247)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-the-body-s-physical-defences-c9c0bbb8) · Published by Druglandscape Ltd.