Investigating transpiration

• What is transpiration in plants?

  Water is taken up by a plant
• What does a faster rate of transpiration indicate?

  A faster rate of water uptake
• What factors affect transpiration rate?

  • Light intensity
  • Temperature
  • Air flow
• How does light intensity affect transpiration?

  Brighter light increases the transpiration rate
• What happens to transpiration in the dark?

  No transpiration occurs
• Why does transpiration stop in the dark?

  Photosynthesis cannot occur
• What happens to stomata when it gets darker?

  They need to be open for CO2
• What is the effect of closed stomata on water escape?

  Very little water can escape
• How does temperature affect transpiration?

  Warmer temperatures increase transpiration
• What happens to water particles in leaves when it's warm?

  They have more energy and move faster
• How does air flow influence transpiration?

  Windy conditions increase transpiration rate
• What does fast-moving air do to water vapor around leaves?

  It sweeps water vapor away
• What is the concentration of water vapor inside the leaf compared to outside?

  Higher inside than outside
• How does water vapor move out of the leaf?

  By diffusion
• How can you estimate transpiration rate using a potometer?

  1. Record starting position of air bubble
  2. Start a stopwatch
  3. Measure distance bubble moves in set time
  4. Calculate transpiration rate
• If a bubble moves 25 mm in 10 minutes, what is the transpiration rate?

  $2.5 \text{ mm min}^{-1}$
• What should you remember when changing variables in transpiration experiments?

  Change one variable at a time
• How can you calculate the percentage change in mass for transpiration rate?

  1. Record initial mass
  2. Record final mass
  3. Calculate change in mass
  4. Divide change by initial mass
  5. Multiply by 100
• What does a greater percentage loss of mass indicate?

  A faster transpiration rate
• What conditions are ideal for transpiration?

  Sunny, warm, and windy conditions
• What is the implication of blowing on a plant?

  It increases transpiration rate
• How does low light intensity affect transpiration?

  It decreases the rate of transpiration
• What is the relationship between light intensity and transpiration?

  • Higher light intensity increases transpiration
  • Lower light intensity decreases transpiration