# Explain how the products of the light-dependent reactions are used in the Calvin cycle to produce triose phosphate (TP).

> IB DP Biology Standard Level (2023 syllabus) — C1.3 Photosynthesis · Explain · 4 marks

## Mark scheme (4 marks)

1. ATP from the light-dependent reactions provides energy for the phosphorylation of glycerate-3-phosphate (G3P) / for the reduction step in the Calvin cycle
2. NADPH acts as a reducing agent / donates hydrogen/electrons to reduce G3P to triose phosphate
3. Carbon dioxide is first fixed into G3P / RuBP accepts CO₂ to form G3P via rubisco, before ATP and NADPH are used
4. Some TP is used to regenerate RuBP (using ATP) so the cycle can continue / some TP leaves the cycle to form organic molecules such as glucose

## Key terms

- [Calvin cycle](https://www.gradenine.co.uk/glossary/calvin-cycle)
- [triose phosphate (TP)](https://www.gradenine.co.uk/glossary/triose-phosphate-tp)

## 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-products-of-the-9ed88f7b) · Published by Druglandscape Ltd.