Water Transport Chap. 30

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Water Transport (Chap. 30)
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• Transpiration (Overview)
• evaporation of water that occurs mainly at leaves
  while stomata are open for the passage of CO2 and
  O2 during photosynthesis.
• the resulting flow of water through the plant is
  called the transpiration stream
• less than 1 of the water reaching the leaves is
  used in photosynthesis and plant growth. Most of
  it is lost in transpiration.

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• Important in order to

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• Environmental factors that affect the rate of
  transpiration
• Light
• Temperature
• Humidity

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• Wind
• Soil water

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• Water (and dissolved mineral ions) Transport in
  Roots, Stems, and Leaves
• Roots (Root Pressure)

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• then, it travels through the cortex in order to
  reach the xylem via two routes

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• Although root pressure plays a role in the
  transport of water in the xylem in some plants
  and in some seasons, it does not account for most
  water transport.

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• Stem (Transpiration Pull)
• water is pulled through the xylem (tracheid and
  vessel element cells) by three forces that create
  an incredible amount of tension
• transpiration
• adhesion
• cohesion

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Leaves (Transpiration)
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• opening of guard cells

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The Big Picture