Stomata and Guard cells

Water is lost through stomata which are found in the leaves of a plant

Stomata close automatically when supplies of water dry up

Open stomata allow gases to be taken in for photosynthesis

If the stomata close then less water is lost however this reduces the intake of carbon dioxide which is needed for photosynthesis

Guard cells have a kidney shape which open and close the stomata

When they become turgid, the stomata open and when flaccid the stomata close

Guard cells are sensitive to light and so they open the stomata during day and close at night

When in bright light the guard cells take up more water by osmosis and so become turgid, becoming turgid means that the inner walls are pulled apart and so open the pore

In darkness the guard cells lose water through osmosis so they become flaccid, this means the inner walls get closer and so close the pore