# Explain how glycolysis converts glucose into pyruvate and contributes to ATP production.

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

## Mark scheme (4 marks)

1. Glucose (a 6-carbon molecule) is phosphorylated / activated using ATP, producing hexose bisphosphate
2. The 6-carbon sugar is split into two 3-carbon molecules (triose phosphate / glyceraldehyde-3-phosphate)
3. Hydrogen / electrons are removed from triose phosphate and accepted by NAD, producing reduced NAD (NADH)
4. A net gain of 2 ATP per glucose is produced by substrate-level phosphorylation during the conversion of triose phosphate to pyruvate

## Key terms

- [glycolysis](https://www.gradenine.co.uk/glossary/glycolysis)
- [pyruvate](https://www.gradenine.co.uk/glossary/pyruvate)

## 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-glycolysis-converts-glucose-into-c01e8a6e) · Published by Druglandscape Ltd.