Key learning points

1. Plant leaves take in carbon dioxide gas from the air for photosynthesis
2. The oxygen made by photosynthesis is released as a gas from leaves into the air
3. This process is called gas exchange
4. Leaves have small holes in their surface called stomata for gas exchange
5. Molecules of gases move through open stomata by diffusion

Keywords

• Gas exchange - Gas exchange in plants is when photosynthesising leaves take in carbon dioxide gas and release waste oxygen gas.

• Stomata - Small holes in the surfaces of a leaf.

• Guard cells - Cells next to stomata that can change shape to open and close the stomata.

• Diffusion - Diffusion is caused by the continuous random movement of molecules of a gas (or of a liquid).

• Net movement - When more molecules of a gas (or of a liquid) diffuse from an area of higher concentration to an area of lower concentration.