# Explain how carbon dioxide and oxygen are removed from the leaves of a flowering plant as waste products of metabolic processes.

> Pearson Edexcel International GCSE Biology (4BI1) — 2.12 Excretion: flowering plants · Explain · 4 marks

> Flowering plants produce waste gases as a result of photosynthesis and respiration. Unlike animals, they do not have a specialised excretory organ, yet these gases must leave the plant body.

## Mark scheme (4 marks)

1. Carbon dioxide is a waste product of respiration (in plant cells)
2. Oxygen is a waste product of photosynthesis (produced in excess of the plant's own respiratory needs)
3. Both gases leave the leaf by diffusion through the stomata
4. Diffusion occurs down a concentration gradient (higher concentration inside the leaf / air spaces to lower concentration outside)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-carbon-dioxide-and-oxygen-649e88b6) · Published by Druglandscape Ltd.