2.20 Describe the structure of the leaf and explain how it is adapted for photosynthesis

Figure 1: Labelled leaf diagram

• Large surface area means more sunlight is absorbed
• Usually very thin, meaning diffusion of carbon dioxide into the leaf can happen quickly
• The stomata open and close, letting carbon dioxide in.
• The epidermis is very thin and completely transparent, so all the sunlight can get to the leaf
• There is a waxy cuticle that prevents water from getting into the leaf and reduces water loss
• The waxy cuticle is also transparent to allow sunlight through
• Palisade mesophyll is packed with chlorophyll and close to the top of the leaf so it gets the most sunlight, making photosynthesis more effective
• In the spongy mesophyll there is quite a lot of air space which allows carbon dioxide to diffuse into the cells.