Gas exchange in plants
- Created by: emews
- Created on: 04-11-17 18:02
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- Gas exchange in plants
- Plants respire during the day and night. But the only photosynthesise during the day
- When there is no photosynthesis, there is a net release of carbon dioxide and a net uptake of oxygen
- If there is enough light during the day then:
- Rate of photosynthesis is higher than the rate of respiration
- there is a net release of oxygen and a net uptake of carbon dioxide
- The structure of the leaf is adapted for gas exchange
- Cells in the spongy meophyll are loosely packed, and covered by a thin film of water.
- Role of stomata
- Stomata control gas exchange in the leaf. Each stomata can be open or closed, depending on how turgid its guard cells are.
- In the light the guard cells absorb water by osmosis, become turgid and the stoma opens
- In the dark, the guard cells lose water, become flaccid and the stoma closes
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