# Explain why the development of antibiotic-resistant bacteria is a serious threat to human health, and describe how the misuse of antibiotics by patients contributes to this problem.

> Pearson Edexcel A-Level Biology A (9BI0) — 5.4 Antibiotics and resistance · Explain · 5 marks

> In recent decades, strains of bacteria such as MRSA have become resistant to many commonly used antibiotics. Scientists and doctors are concerned that antibiotic resistance is increasing at a faster rate than new antibiotics are being developed.

## Mark scheme (5 marks)

1. Antibiotics kill or prevent the growth of bacteria (but have no effect on viruses/host cells)
2. Some bacteria have a random mutation that makes them resistant to an antibiotic
3. Resistant bacteria survive and reproduce, passing on the resistance (natural selection / survival of the fittest)
4. If resistance spreads widely, infections become very difficult or impossible to treat, leading to more serious illness or death
5. Patients not completing their course of antibiotics (or taking antibiotics unnecessarily) means non-resistant bacteria are not all killed, giving resistant strains a greater selective advantage / increasing the chance of resistant strains surviving and spreading

## Key terms

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

## 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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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-development-of-antibiotic-resistant-5d6bcea4) · Published by Druglandscape Ltd.