# During the cell cycle, DNA replication occurs in the nucleus before a cell can divide by mitosis. Explain how DNA replication produces two identical copies of DNA from one original molecule.

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

> A cell in the root tip of a plant is about to undergo mitosis. Before this can happen, the cell must replicate its DNA during interphase.

## Mark scheme (5 marks)

1. The two strands of the DNA double helix unwind / separate
2. Each original strand acts as a template for a new strand
3. New complementary bases pair up with the bases on each template strand
4. Two new double-stranded DNA molecules are formed
5. Each new DNA molecule contains one original (template) strand and one newly synthesised strand, so both copies are identical to the original

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](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/during-the-cell-cycle-dna-replication-40a598d7) · Published by Druglandscape Ltd.