transpiration

• What is the main pathway for water travel in plants?

  Xylem
• Through which pathways does water travel in the leaf?

  Apoplast, symplast, and vacuolar pathways
• What is transpiration?

  Loss of water vapor from leaves
• What causes the transpiration pull?

  Water molecules leaving xylem cells
• What is the term for the cohesive forces between water molecules?

  Cohesion
• What is the role of adhesive forces in transpiration?

  They help water stick to xylem walls
• What theory explains the maintenance of water column in xylem?

  Cohesion-Tension theory
• What is capillary action in relation to water movement?

  Water rises in narrow tubes
• What factors affect the rate of transpiration?

  1. Temperature
  2. Humidity
  3. Air movement
  4. Light intensity
• How does temperature affect transpiration rate?

  Increases evaporation and diffusion rates
• What happens to transpiration rate when humidity increases?

  It decreases
• How does air movement influence transpiration?

  Increases rate by removing saturated air
• What is the effect of light intensity on stomatal opening?

  Higher light intensity increases stomatal opening
• How is the rate of transpiration measured using a potometer?

  • Measures water absorption
  • Assumes turgid cells equal transpiration rate
  • Air bubble movement indicates water uptake
• What is the purpose of cutting the shoot under water when setting up a potometer?

  To prevent air bubbles forming
• What should be done to the leaves when setting up a potometer?

  Keep the leaves dry
• What is the function of the reservoir in a potometer?

  Returns the air bubble to starting point
• What is the role of the scale in a potometer?

  Measures the volume of water uptake
• Why is it important to ensure all joints in a potometer are airtight?

  To prevent water loss and inaccuracies