# Explain how the discovery of DNA helped scientists to understand evolution and classification. Include how this changed the way organisms were grouped.

> AQA GCSE Biology (8461) — 4.6.3 The development of understanding of genetics and evolution · Explain · 4 marks

## Mark scheme (4 marks)

1. DNA carries genetic information / genetic code that can be compared between organisms
2. Similarities in DNA sequences between organisms indicate common ancestry / evolutionary relationships
3. DNA evidence led to the development of the three-domain system (by Carl Woese) / organisms reclassified into Archaea, Bacteria and Eukaryota
4. This changed classification because organisms previously grouped by physical appearance / observable characteristics alone were reclassified using molecular / DNA evidence

## Key terms

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

## 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-how-the-discovery-of-dna-e68b878e) · Published by Druglandscape Ltd.