The evaportion of water from a plant's surface, particularly through the stomata when they open to allow the entry of CO2 for photosynthesis.
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List 4 factors that affect the rate of transpiration.
Light, temperature, humidity and air movement.
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How does light affect the rate of transpiration?
Stomata open during daylight hours to allow CO2 to enter for photosynthesis. This increases rate of transpiration as water evaporates from mesophyll cells and diffuses out of leaf.
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How does temperature affect the rate of transpiration?
Increase temp = increase rate of transpiration by providing water molecules with more Ek allowing them to evaporate more readily. Increase in temp also lowers relative humidity of air outside leaf = increase rate of transpiration.
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How does humidity affect the rate of transpiration?
Humidity refers to water vapour content of air surrounding plant. Increase humidity=increase water potential of air so decreases rate of transpiration because water potential gradient for diffusion of water decreses.
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How does air movement affect the rate of transpiration?
Air movement removes water vapour from leaf surface so increases water potential gradient between leaf surface and air around it thus increasing rate of transpiration.
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What effect does still air have on the rate of transpiration?
In still air, water vapour builds up around leaf which decreases water potential gradient between leaf surface and air surrounding it thus decreasing the rate of transpiration.
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Other cards in this set
Card 2
Front
List 4 factors that affect the rate of transpiration.
Back
Light, temperature, humidity and air movement.
Card 3
Front
How does light affect the rate of transpiration?
Back
Card 4
Front
How does temperature affect the rate of transpiration?
Back
Card 5
Front
How does humidity affect the rate of transpiration?
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