# A student says: 'DNA is a polymer made from monomers called nucleotides.' Explain what this statement means, and explain why it is important for cells to be able to break polymers down into their monomers.

> AQA A-Level Biology (7402) — 3.1.1 Monomers and Polymers · Explain · 5 marks

## Mark scheme (5 marks)

1. A monomer is a small / single molecule that is the repeating unit (of a polymer)
2. A polymer is a large molecule made from many monomers joined together
3. The monomers are joined by chemical bonds (to form the polymer)
4. Breaking polymers into monomers releases the smaller molecules so they can be used / reused by the cell
5. Monomers released can be used to build new / different polymers (or for respiration / other cellular processes)

## Key terms

- [monomer](https://www.gradenine.co.uk/glossary/monomer)
- [polymer](https://www.gradenine.co.uk/glossary/polymer)
- [nucleotide](https://www.gradenine.co.uk/glossary/nucleotide)

## Related

- [Revision notes for AQA A-Level Biology (7402)](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/a-student-says-dna-is-a-132699d4) · Published by Druglandscape Ltd.