Guard Cell

Key Stage 3

The two guard cells can be seen at the leaf.

A guard cell is a specialised cell in a plant leaf which contains can change shape to allow or stop gases from getting into the leaf.

Guard cells can change shape to open and close a hole called a stoma.


The under side of a leaf showing guard cells and stomata.

Guard cells are shaped with a gap between them called a stoma.

There are more guard cells found on the bottom of the leaf.

Photosynthesis needs water, so guard cells are there to make sure the leaves don't use up too much water and die of dehydration.

Guard cells fill with water to become turgid, making the stomata larger. This allows carbon dioxide into the leaf for photosynthesis.

When the leaf gets dehydrated the guard cells become flaccid making the stomata smaller. This stops carbon dioxide from getting into the leaf and prevents photosynthesis


Turgid guard cells are full of water and have a hole called a stoma between them to allow air in and out.	Flaccid guard cells are dehydrated and the stoma is blocked stopping air form getting in or out of the leaf.