# When a person is infected by influenza for the first time, white blood cells respond to destroy the pathogen. Describe the roles of lymphocytes and phagocytes in this immune response, and explain how the body responds more quickly if the same pathogen enters the body a second time.

> Eduqas A-Level Biology — 3.4 Population size and ecosystems · Describe · 5 marks

## Mark scheme (5 marks)

1. Lymphocytes detect antigens on the surface of the pathogen and release/produce antibodies
2. Antibodies are specific / complementary to the antigen on the influenza pathogen and bind to it to neutralise it
3. Phagocytes engulf / ingest and digest the pathogen (phagocytosis)
4. After the first infection, memory cells remain in the body
5. On second exposure, memory cells rapidly divide and produce the correct antibodies more quickly, destroying the pathogen before symptoms appear

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/when-a-person-is-infected-by-5b5426d6) · Published by Druglandscape Ltd.