1.1 They make food for a plant. This process is
called photosynthesis because plants use light
energy from the Sun to make food.
1.2 A plant's structure allows it to carry
photosynthesis efficiently. Its leaves are large
and flat at at right angles to the directon of
1.3 Leaves are arranged so that they do not
overlap and shade each other. In shady areas,
plants grow more leaves to capture the same
ammount of light.
1.4 A leaf is a organ made of several different kinds of cells. The leaf has a factory for making food. The top
layer, the epidermis, is transparent. It has a waxy waterproof layer over it that stops the leaf from
drying out. Light passes through the the epidermis to the next layer of cells called the palisade layer.
Inside the leaf most cells are green. They contain green chloroplasts where food is made from light.
1.5 Palisade cells are specialised for photosynthesis. They are provided with water by the veins in a leaf.
Below the palisade layer is a layer of cells called the spongy mesophyll. In this layer the air spaces act as
reservoirs for the gases that palisade cells need. There is another layer of epidermis on the lower
surface of the leaf. This also waterproof. Gases such as carbon dioxide enter and leave a leaf through tiny
pores called stomata. Guard cells by each stoma shut the stomata at night.