# Explain how memory cells contribute to a secondary immune response that is faster and more effective than the primary immune response.

> IB DP Biology Higher Level (2023 syllabus) — C3.2 Defence against disease · Explain · 4 marks

## Mark scheme (4 marks)

1. Memory cells are long-lived lymphocytes (B or T memory cells) that persist after the primary immune response.
2. On re-exposure to the same antigen, memory cells rapidly proliferate by clonal expansion.
3. Rapid differentiation of memory cells into plasma cells / effector T cells produces a larger and faster antibody response / cell-mediated response than during the primary response.
4. The pathogen is eliminated before symptoms develop / the secondary response is more effective because antibody levels peak sooner and at a higher concentration.

## Key terms

- [memory cells](https://www.gradenine.co.uk/glossary/memory-cells)
- [secondary immune response](https://www.gradenine.co.uk/glossary/secondary-immune-response)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-memory-cells-contribute-to-bec0d2be) · Published by Druglandscape Ltd.