9.1  Transport in the Xylem of Plants

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Essential Idea:

Structure and function are  

correlated in the xylem of plants


  • Transpiration is the inevitable consequence of gas exchange in the leaf
  • Plants transport water from the roots to the leaves to replace losses from transpiration
  • The cohesive property of water and the structure of the xylem vessels allow transport under tension
  • The adhesive property of water and evaporation generate tension forces in leaf cell walls
  • Active uptake of mineral ions in the roots causes absorption of water by osmosis


  • Adaptations of plants in deserts and in saline soils for water conservation
  • Models of water transport in xylem using simple apparatus including blotting or filter paper, porous pots and capillary tubing


  • Drawing the structure of primary xylem vessels in sections of stems based on microscope images
  • Measurement of transpiration rates using potometers
  • Design of an experiment to test hypotheses about the effect of temperature or humidity on transpiration rates