# A person receives a vaccination against influenza. Some months later, the same person is exposed to the influenza virus. Explain why the person does not develop the disease on this second exposure.

> Pearson Edexcel A-Level Biology A (9BI0) — 5.3 Immune response · Explain · 5 marks

> Vaccination programmes are used worldwide to protect individuals from communicable diseases. The influenza vaccine introduces antigens into the body without causing the disease itself.

## Mark scheme (5 marks)

1. The vaccine contains antigens from the influenza virus
2. B-lymphocytes are activated and produce antibodies specific to those antigens
3. Memory cells are produced following the first immune response (to the vaccine)
4. On second exposure, memory cells recognise the same antigen and respond faster / more quickly than the primary response
5. Large quantities of antibodies are produced quickly enough to destroy the pathogen before symptoms develop / before the person becomes ill

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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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