Stomata and guard cells

What is the stomata?

Small holes in a leaf that allow gas exchange to occur

What does the stomata do at night?

Close - dont need to open to let CO2 in = very little water can escape

What closes the stomata?

Guard cells

How are guard cells adapted to open and close stomata?

1) Kidney shaped

2) Guard cells fill with water

3) Become flaccid when they lose water

4) Thin outer walls and thickened inner walls

5) Sensitive to light

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Adapted for gas exchange and controlling water loss

Why do the guard cells fill with water?

Plump + turgid = makes the stomata open so gases can be exchanged for photosynthesis

Why do the guard cells become flaccid when losing water?

Makes the stomata close = helps stop too much water vapour escaping

Why are guard cells sensitive to light?

They close at night to save water without losing out on photosynthesis