How are leaves adapted for photosynthesis?
- Leaves are broad with a large surface area so that they are exposed to more light and can maximize light absorption. - They are thin and flat so that carbon dioxide has a shorter distance to diffuse and the diffusion therefore occurs at a faster rate. - Leaf has a large network of veins. The Phloem and Xylem form a network of vascular bundles that provide the leaf with water needed for the photosynthesis and also take any glucose made. The veins also support the leaf’s structure. - Stomata are positioned on the leaf so that gaseous exchange can take place: Carbon dioxide is taken in and oxygen (waste product of photosynthesis) is removed. - Leaf’s upper epidermis layer is transparent so that light rays can go through to reach the palisade layer. - There is a wax cuticle (thin layer of transparent wax) to protect the leaf without blocking sunlight and still enabling diffusion of carbon dioxide in and oxygen out. - Upper Palisade layer is full of chloroplasts which contain chlorophyll and can therefore absorb as much of the light as possible. They can be moved around the palisade cells so that more light can be absorbed. This is where most of the light is so very conveniently located. The palisade cells are long and thin, so lots are packed tightly together. - Leaf has a spongy Mesophyll layer so that there are lots of air spaces for diffusion of Carbon Dioxide and water vapour to be easier – therefore maximising the rate of photosynthesis with larger surface area. - The lower epidermis has stomata.
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