# A scientist is studying wheat plants growing in two different fields. In Field A, the wheat plants are grown in conditions where carbon dioxide levels are kept artificially high. In Field B, the wheat plants are grown under normal atmospheric carbon dioxide levels. Both fields receive the same amount of light and water. Explain why the wheat plants in Field A are likely to produce a greater biomass than those in Field B.

> OCR A-Level Biology B — Advancing Biology (H422) — 4.1 Photosynthesis · Explain · 5 marks

> Photosynthesis is an endothermic reaction that takes place in the chloroplasts, converting carbon dioxide and water into glucose and oxygen using light energy. The glucose produced can be used by the plant to build new biological molecules, contributing to biomass.

## Mark scheme (5 marks)

1. Photosynthesis uses carbon dioxide (as a reactant)
2. Higher carbon dioxide concentration increases the rate of photosynthesis
3. More glucose is produced (as a result of faster photosynthesis)
4. Glucose is used to build new biological molecules / used for growth
5. Therefore greater biomass is produced in Field A

## Key terms

- [biomass](https://www.gradenine.co.uk/glossary/biomass)
- [carbon dioxide](https://www.gradenine.co.uk/glossary/carbon-dioxide)

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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/a-scientist-is-studying-wheat-plants-3abaf8d8) · Published by Druglandscape Ltd.