The evaporation of water vapour from plants using the stomata
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What four factors affect transpiration?
Light, temperature, wind movement, humidity
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How does temperature affect transpiration?
Higher temp = more kinetic energy. Molecules move faster so more evaporation. Water potential outside the leaf more negative than inside the leaf so water moves out of the plant by transpiration = greater conc grad. Higher temp = more transpiration,
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How does light intensity affect transpiration?
More light - more evaporation as stomata open - carbon dioxide moves in, water moves out - more transpiration
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How does wind movement affect transpiration?
More wind movement = more evaporation as excess water is evaporated and moved out of plant = water potential reaches equilibrium between both surfaces
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How does humidity affect transpiration?
More humid atmosphere = more water in atmosphere = higher water potential outside of the plant, less osmosis so less transpiration
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Name the five xerophytic plant adaptations to avoid water loss.
Hairy leaves, rolled up leaves, stomata in pits, reduced SA, thick cuticle
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What is the benefit of a thick cuticle?
Waxy cuticle - waterproof - acts as a barrier for water loss and reduces water potential gradient so less transpiration
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What is the benefit of hairy leaves?
Trap moist air, reduce water potential gradient, reduce transpiration
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What is the benefit of rolled leaves?
Trap air, saturate it with water, reduce water potential gradient, reduce transpiration
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What is the benefit of a reduced SA?
Fewer stomata, reduces water potential gradient, reduces transpiration
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What is the benefit of stomata in pits?
Collect water, reduces water potential gradient, reduces transpiration
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