# Describe how the body responds when a pathogen enters the bloodstream for the first time, and explain why a second infection by the same pathogen is overcome more quickly.

> Cambridge International IGCSE Biology (0610) — 10.1 Diseases and immunity · Describe · 4 marks

## Mark scheme (4 marks)

1. White blood cells (lymphocytes) produce antibodies in response to the pathogen's antigens
2. Antibodies are complementary / specific to the antigen on that particular pathogen
3. Memory cells are produced after the first infection and remain in the blood
4. On second exposure, memory cells recognise the antigen and produce antibodies more quickly / in greater quantity

## Key terms

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

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-the-body-responds-when-3369bc7b) · Published by Druglandscape Ltd.