# Explain how the RNA world hypothesis accounts for the origin of self-replicating molecules before the first cells arose on Earth.

> IB DP Biology Standard Level (2023 syllabus) — A2.1 Origins of cells · Explain · 4 marks

## Mark scheme (4 marks)

1. RNA can act as both a catalyst (ribozyme) and carry genetic information
2. RNA could therefore replicate itself without the need for protein enzymes
3. RNA molecules that replicated more accurately or efficiently would be selected, allowing evolution of RNA sequences
4. RNA world precedes / sets the stage for DNA and protein-based life, with RNA eventually being replaced by DNA for information storage and proteins for catalysis

## Key terms

- [RNA world hypothesis](https://www.gradenine.co.uk/glossary/rna-world-hypothesis)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](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-rna-world-hypothesis-a875a5aa) · Published by Druglandscape Ltd.