# Explain how antibiotic-resistant bacteria, such as MRSA, develop in a population of bacteria.

> Cambridge International IGCSE Biology (0610) — 15.1 Drugs · Explain · 4 marks

## Mark scheme (4 marks)

1. A mutation occurs in a bacterial cell that makes it resistant to an antibiotic
2. When the antibiotic is used, non-resistant bacteria are killed but the resistant bacterium survives
3. The resistant bacterium reproduces, passing on the resistance to offspring
4. Over time the population of resistant bacteria increases, making the antibiotic ineffective / leading to infections like MRSA that are very difficult to treat

## Key terms

- [antibiotic](https://www.gradenine.co.uk/glossary/antibiotic)
- [antibiotic-resistant bacteria](https://www.gradenine.co.uk/glossary/antibiotic-resistant-bacteria)
- [MRSA](https://www.gradenine.co.uk/glossary/mrsa)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](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-antibiotic-resistant-bacteria-such-as-28626527) · Published by Druglandscape Ltd.