Measuring transpiration and stomata

• What is a potometer used for?


  To estimate the transpiration rate of a plant
• Why can the rate of transpiration be estimated by measuring water uptake?


  Because water uptake is directly related to water loss by the leaves
• What should you do after setting up the potometer apparatus?


  Record the starting position of the air bubble
• How do you measure the transpiration rate using a potometer?


  By recording the distance moved by the air bubble per unit time
• Why is it important to keep conditions constant during the transpiration experiment?


  To ensure accurate and reliable results
• What shape are guard cells and what is their function?


  They are kidney-shaped and open and close the stomata
• What happens to guard cells when a plant has lots of water?


  They fill with water and become turgid, opening the stomata
• What occurs to guard cells when a plant is short of water?


  They lose water and become flaccid, closing the stomata
• How do the outer and inner walls of guard cells contribute to their function?


  The outer walls are thinner, allowing for easier opening and closing
• Why do guard cells close at night?


  To save water without losing out on photosynthesis
• Where are stomata usually found in greater numbers on a leaf?


  On the undersides of leaves
• Why are there usually more stomata on the underside of leaves?


  Because the lower surface is shaded and cooler, reducing water loss
• What is the role of guard cells in a leaf?


  They control gas exchange and water loss
• How can you compare the distribution of stomata in different leaves?


  • Peel the epidermal tissue off some leaves
  • Mount them on microscope slides
  • Observe and compare the stomata distribution
• Which plant is likely to have fewer stomata per cm² on the underside of its leaves: Aloe vera or Primroses?


  Aloe vera is likely to have fewer stomata due to its adaptation to hot, dry areas
• Why might Aloe vera plants have fewer stomata compared to Primroses?


  Because they are adapted to conserve water in arid environments