Top Layer Of The Leaf example essay topic
310 words
A leaf needs carbon dioxide, water and sunlight to photosynthesis. The leaf is well adapted for photosynthesis, although leafs do vary depending on the condition they are growing in. Firstly, leaves are usually very large and thin. This gives a larger surface area for trapping as much sunlight as possible. The top layer of the leaf contains the cuticle, which is waterproof to protect the leaf, and the upper epidermis, which is transparent to let in the sunlight. A leaf also contains lots of chloroplasts, which are in the palisade cell of the leaf. Chloroplasts are small parcels of chlorophyll, which is a green pigment that turns the light energy into glucose. These chloroplasts are usually found towards the top of the leaf, so that they are easily exposed to the sunlight. Below the palisade layer is the spongy layer. The function of the spongy layer is to allow the gases to diffuse through. Contained within the spongy layer, are veins, which carry the water from the roots to the leaf. The Xylem vessel, which carries water and mineral salts, is dead, so minimizing the usage of water.
At the underside of the leaf is the lower epidermis. There are spaces in this layer, where there are guard cells. These guard cells let carbon dioxide into the plant. The whole opening at the bottom of the leaf (they are underneath so they do not get clogged up with rain water or pollution etc.) is called stomata.
Leafs have many variations to suite the conditions they grow in. For example, in a place where there is not much water available, a leaf would have fewer stomata, because they let out valuable water, and a thicker cuticle, so water cannot be evaporated from the leaf.
