# A student cuts their finger and bacteria enter the wound. Explain how the immune system responds to destroy these bacteria.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 6 Immunity, Infection and Forensics · Explain · 5 marks

> When the skin is broken, pathogens such as bacteria can enter the body and trigger an immune response.

## Mark scheme (5 marks)

1. White blood cells / phagocytes engulf and digest (ingest) the bacteria by phagocytosis
2. Lymphocytes recognise antigens on the surface of the bacteria
3. Lymphocytes produce specific antibodies that bind to / complement the antigens on the bacteria
4. Antibodies cause the bacteria to clump together (agglutinate) or neutralise / mark them for destruction by phagocytes
5. Memory cells are produced so that if the same bacteria enter the body again, antibodies are produced more quickly / in greater quantities

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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-student-cuts-their-finger-and-c91e6ef5) · Published by Druglandscape Ltd.