# Explain how the body responds to a pathogen the first time it enters the body. Include in your answer the roles of lymphocytes and antibodies.

> AQA A-Level Biology (7402) — 3.2.4 Cell Recognition and the Immune System · Explain · 5 marks

## Mark scheme (5 marks)

1. Lymphocytes detect antigens on the surface of the pathogen (that are foreign / not recognised as self)
2. Lymphocytes produce antibodies that are specific / complementary to that antigen
3. Antibodies bind to / attach to the antigens on the pathogen
4. The response is slow / takes time on first exposure because the correct lymphocyte must be found and multiply
5. Memory lymphocytes / memory cells are produced that remain in the body after the infection is cleared

## Key terms

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

## Related

- [Revision notes for AQA A-Level Biology (7402)](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/explain-how-the-body-responds-to-6ad04640) · Published by Druglandscape Ltd.