Stoma
Key Stage 3
Meaning
Stomata are holes in the leaf that can open and close to allow or stop gas exchange in the leaf.
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| The under side of a leaf showing guard cells and stomata. |
About Stomata
- There are usually more stomata on the underside of a leaf than the top side.
- Stomata close when the leaf becomes dehydrated. This stops photosynthesis, which needs water, so it helps stop the dehydration from getting worse.
The Process:
- 1. Plant becomes dehydrated.
- 2. Guard Cells become flaccid.
- 3. Stomata close.
- 4. Carbon Dioxide can no longer enter the leaf.
- 5. Photosynthesis stops.
- 6. Respiration continues to make water and water is taken up by the roots.
- 7. Plant becomes hydrated again.
- 8. Guard cells become turgid.
- 9. Stomata open.
- 10. Carbon Dioxide can now get into the leaf.
- 11. Photosynthesis starts again using up the water.