# Explain how the link reaction connects glycolysis to the Krebs cycle during aerobic cell respiration.

> IB DP Biology Standard Level (2023 syllabus) — C1.2 Cell respiration · Explain · 4 marks

## Mark scheme (4 marks)

1. Pyruvate produced in glycolysis is transported from the cytoplasm into the mitochondrial matrix.
2. Pyruvate is decarboxylated, releasing carbon dioxide, and oxidised to form acetyl groups / acetate.
3. The acetyl group combines with coenzyme A to form acetyl CoA, which feeds into the Krebs cycle.
4. NAD is reduced to NADH during the link reaction, contributing to ATP production via oxidative phosphorylation / the electron transport chain.

## Key terms

- [link reaction](https://www.gradenine.co.uk/glossary/link-reaction)
- [Krebs cycle](https://www.gradenine.co.uk/glossary/krebs-cycle)

## 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-link-reaction-connects-eac36e1c) · Published by Druglandscape Ltd.