Transpiration and cohesion

• What is transpiration?

  Loss of water vapor from stomata
• What causes transpiration?

  Evaporation of water vapor
• Where are stomata mainly found?

  On the lower side of the leaf
• What are the four key conditions affecting transpiration rates?

  • Light intensity
  • Temperature
  • Humidity
  • Wind
• How does light intensity affect transpiration?

  Higher light intensity increases transpiration rate
• Why does temperature affect transpiration rates?

  Higher temperature increases water molecule kinetic energy
• What is the effect of humidity on transpiration?

  Higher humidity decreases transpiration rate
• Why does wind affect transpiration rates?

  Wind carries away water vapor, increasing evaporation
• What does the cohesion tension theory explain?

  How water moves up against gravity in plants
• What is cohesion in the context of water molecules?

  Sticking together of water molecules
• How do hydrogen bonds relate to cohesion?

  They allow water molecules to stick together
• What is adhesion in the context of water movement?

  Water molecules sticking to xylem walls
• How does capillarity affect water movement in plants?

  Narrow xylem increases water movement upward
• What is root pressure?

  Pressure from water entering roots by osmosis
• How does root pressure contribute to water movement?

  It pushes water upward in the xylem
• What are the three components of the cohesion tension theory?

  • Cohesion: water molecules stick together
  • Adhesion: water molecules stick to xylem walls
  • Root pressure: pushes water upward from roots
• How does transpiration create a pull on the water column?

  Evaporation lowers pressure, pulling water up
• What happens to the xylem walls as water is pulled up?

  They are drawn inward, narrowing the xylem
• What is the overall effect of the cohesion tension theory?

  It explains water movement against gravity
• What is the final summary of transpiration?

  Loss of water vapor from stomata by evaporation
• What is the relationship between transpiration and the cohesion tension theory?

  Transpiration creates a pull that moves water up