Structure and function of stomata

The stomata control gas exchange in the leaf. Each stoma can be open or closed, depending on how turgid its guard cells are.

The stomata can open and close to:

  • control water lost by transpiration
  • allow gas exchange
The structure and function of stomata

Diffusion of carbon dioxide into the leaf for photosynthesis and oxygen and water vapour out of the leaf, is greatest when the stomata are open during the day.

Stomata are found mainly on the lower surface of the leaf to reduce water loss by transpiration.