# Chlamydia is a communicable disease caused by a bacterium. Explain how the human body attempts to defend itself against a chlamydia infection, including both non-specific defences and the specific immune response.

> WJEC A-Level Biology (Wales) — 3.5 Human impact on the environment · Explain · 5 marks

## Mark scheme (5 marks)

1. Non-specific defence: skin / mucus / stomach acid acts as a barrier to prevent pathogens entering the body
2. White blood cells detect the chlamydia bacterium using antigens on its surface
3. Lymphocytes produce antibodies that are specific / complementary to the chlamydia antigens
4. Phagocytes engulf / ingest and digest the bacterium (phagocytosis)
5. Memory cells remain after infection so that if chlamydia enters the body again, antibodies are produced more quickly

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/chlamydia-is-a-communicable-disease-caused-d8da0db6) · Published by Druglandscape Ltd.