Transpiration

• What is transpiration in plants?

  Loss of water from the plant
• What causes transpiration in plants?

  Evaporation and diffusion of water
• Where does most transpiration occur in a plant?

  At the leaves
• What happens to water levels in leaves during transpiration?

  A slight shortage of water occurs
• How does water move from roots to leaves during transpiration?

  Through xylem vessels
• What is the transpiration stream?

  A constant flow of water through the plant
• What is the role of stomata in leaves?

  Gas exchange
• Why do stomata open during the day?

  To allow gas exchange for photosynthesis
• How does humidity affect transpiration?

  Drier air increases transpiration rate
• What effect does light intensity have on transpiration?

  Greater light increases transpiration rate
• How does temperature influence transpiration?

  Warmer air increases transpiration rate
• What is the relationship between air flow and transpiration?

  Faster air flow increases transpiration rate
• How can transpiration rate be estimated?

  By measuring water uptake by the plant
• What is a potometer used for?

  Measuring the rate of transpiration
• What happens to guard cells when a plant has lots of water?

  They become turgid and open stomata
• What is the function of guard cells?

  To control the opening and closing of stomata
• How do guard cells respond when a plant is short of water?

  They lose water and close stomata
• Why do stomata usually occur more on the underside of leaves?

  To reduce water loss in sunlight
• How do different environmental conditions affect stomata distribution?

  Different plants adapt stomata for their environments
• What are the four main factors affecting transpiration rate?

  1. Light intensity
  2. Temperature
  3. Air flow
  4. Humidity
• How are guard cells adapted for their function?

  • Kidney-shaped to open and close stomata
  • Thin outer walls and thickened inner walls
  • Sensitive to light, closing at night
• What is the relationship between transpiration and photosynthesis?

  • Transpiration is a side-effect of photosynthesis
  • Stomata open for gas exchange during photosynthesis
  • Water loss occurs as gases are exchanged
• How do environmental conditions influence transpiration?

  • Light intensity increases transpiration
  • Higher temperatures speed up evaporation
  • Good air flow enhances diffusion
  • Lower humidity increases water loss