# Explain why tobacco mosaic virus (TMV) reduces the growth of infected plants.

> AQA GCSE Biology (8461) — 4.3.3 Plant disease (Bio only) · Explain · 4 marks

> Tobacco mosaic virus (TMV) is a widespread plant pathogen that infects many species, including tomatoes and peppers. Plants infected with TMV show a distinctive mosaic pattern of discolouration on their leaves.

## Mark scheme (4 marks)

1. TMV causes a mosaic (discolouration/pattern) on leaves, meaning chloroplasts are damaged or the leaf is unable to produce normal chlorophyll
2. Discoloured/affected areas of the leaf cannot photosynthesise (at the normal rate)
3. Less glucose is produced by photosynthesis
4. Less glucose means less energy / fewer raw materials available for growth (cell division / protein synthesis / cellulose production)

## Key terms

- [tobacco mosaic virus](https://www.gradenine.co.uk/glossary/tobacco-mosaic-virus)
- [mosaic](https://www.gradenine.co.uk/glossary/mosaic)

## Related

- [Revision notes for AQA GCSE Biology (8461)](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-tobacco-mosaic-virus-tmv-2e30aa24) · Published by Druglandscape Ltd.