9.1 Transport in the Xylem of Plants

Essential Idea

• Structure and function are correlated in the xylem of plants

Understandings

• Transpiration
  • Inevitable consequence of gas exchange in the leaf.
• Water Transport
  • Water is transported from roots to leaves to replace losses due to transpiration.
• Cohesive Property of Water
  • Cohesion and xylem vessel structure enable transport under tension.
• Adhesive Property of Water
  • Adhesion and evaporation create tension forces in leaf cell walls.
• Active Uptake of Mineral Ions
  • Mineral ions uptake in roots causes water absorption by osmosis.

Applications

• Adaptations for Water Conservation
  • Plant adaptations in deserts and saline soils to conserve water.
• Models of Water Transport
  • Use of simple apparatus such as blotting or filter paper, porous pots, and capillary tubing to model water transport in xylem.

Skills

• Drawing Xylem Structures
  • Draw the structure of primary xylem vessels using microscope images.
• Measuring Transpiration Rates
  • Use potometers to measure transpiration rates.
• Experimental Design
  • Design experiments to test the effects of temperature or humidity on transpiration rates.