Transpiration

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Transpiration

Transpiration

  • Leaves lose water in the form of water vapour from their stomata
  • There is little water in the air around a leaf, therefore water diffuses to the lower water potential of the air through the stomata
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Factors Affecting Transpiration

Light

  • Stomata only open during photosynthesis
  • Photosynthesis only occurs in light
  • Increased light intensity causes increased rate of transpiration
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Factors Affecting Transpiration

Temperature

  • As temperature increases, there is more kinetic energy 
  • Therefore water evaporates quicker
  • Water evaporates from stromata rapidly

Higher Temperature Increases Rate of Transpiration

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Factors Affecting Transpiration

Humidity

  • High humidity means more water is in the air
  • Reduces water potential gradient
  • Therefore rate of transpiration is decreased
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Factors Affecting Transpiration

Air Movement

  • Water diffuses through stomata and accumulates as vapour around the stomata on the outside of the leaf
  • The water potential of the stomata is increased
  • This lowers the water potential gradient between the leaf and air
  • Reducing the rate of transpiration

If air movement increases, this moves the accumulated water 

and causes rate of transpiration to increase.

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