# Explain how the human body uses antibodies to destroy a pathogen after it has entered the bloodstream.

> WJEC A-Level Biology (Wales) — 3.4 Population size and ecosystems · Explain · 5 marks

> When a pathogen enters the human body, the immune system produces antibodies as part of the specific defence response.

## Mark scheme (5 marks)

1. White blood cells / lymphocytes detect antigens on the surface of the pathogen
2. Lymphocytes release / produce complementary antibodies specific to that antigen
3. Antibodies bind to the antigens on the surface of the pathogen
4. Antibodies clump pathogens together (agglutination) / neutralise the pathogen, making it easier to destroy
5. Memory cells remain after infection so that if the same pathogen enters the body again, antibodies are produced more quickly

## 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)

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