2.41 explain how the structure of the leaf is adapted for gas exchange

The leaf is adapted for gas exchange in many ways, here are a few...

- It is thin, meaning gases only have to travel a short distance (to reach the cells where they are needed)
- They are broad, meaning there's a large surface area for diffusion
- Air spaces inside the leaf let CO2 and O2 move easily between cells (they also increase the surface area for gas exchange)
- Stomata let CO2 and O2 diffuse - they also allow water to escape (transpiration)
- Stomata close when its dark as photosynthesis doesn't occur in the dark so there is no need for stomata to let in CO2. When stomata are closed no water can escape - this stops the plant drying out.

NOTE: the opening and closing of stomata is controlled by guard cells