# Explain how the RNA world hypothesis accounts for two major challenges in the origin of life.

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

> The RNA world hypothesis proposes that RNA molecules were the first informational and catalytic polymers in early cells, preceding both DNA and protein-based life.

## Mark scheme (4 marks)

1. Challenge 1 — information storage: RNA can store genetic information in its nucleotide sequence, acting as a hereditary molecule before DNA evolved
2. Challenge 1 — mechanism: because RNA is single-stranded it can fold and base-pair with itself, enabling self-replication / template-directed copying without protein enzymes
3. Challenge 2 — catalysis: RNA molecules can fold into three-dimensional structures that function as ribozymes / biological catalysts
4. Resolution of the 'chicken-and-egg' problem: because a single RNA molecule can both carry information and catalyse reactions, it resolves the paradox that nucleic acids need proteins to replicate and proteins need nucleic acids to be synthesised

## Key terms

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

## Related

- [Revision notes for IB DP Biology Higher 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-a1ec65bb) · Published by Druglandscape Ltd.