# DNA is a polymer that forms a double helix structure. Describe the structure of DNA and explain how it is replicated inside a cell.

> WJEC A-Level Biology (Wales) — 1.5 Nucleic acids and DNA replication · Describe and Explain · 5 marks

> DNA replication ensures that every new cell produced during the cell cycle receives an identical copy of the genetic information.

## Mark scheme (5 marks)

1. DNA is made of two strands twisted around each other to form a double helix
2. DNA contains bases that pair up / complementary base pairing holds the two strands together
3. DNA replication occurs in the nucleus
4. The two strands of the DNA double helix unwind / separate
5. Each original strand acts as a template so that two identical copies of DNA are produced

## Key terms

- [DNA](https://www.gradenine.co.uk/glossary/dna)
- [double helix](https://www.gradenine.co.uk/glossary/double-helix)

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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/dna-is-a-polymer-that-forms-6d2e10b3) · Published by Druglandscape Ltd.