[PPQs] Transpiration

• Q3 (d) What is the median number of stomata on the upper surface of the leaf?

  1

  
• Q3 (e) Calculate the value of X in the table. Give your answer to 2 significant figures.

  42

  
• Q3 (f) The plant used in this investigation has very few stomata on the upper surface of the leaf. Explain why this is an advantage to the plant.

  Less water loss via evaporation required for photosynthesis

  
• Q4 (a) Which leaf, A, B or C, lost most water?

  C

  
• Q4 (b) (i) Name cell X

  Guard cell

  
• Q4 (b) (ii) The petroleum jelly had a greater effect when it was spread on the lower surface than when it was spread on the upper surface. Use information from the diagram to explain why

  There are more stomata in the lower surface than upper surface meaning there is going to be a bigger difference in effect

  There are no guard cells in the upper surface

  
• Q5 (i) Give one variable that the student controlled in this investigation.

  Leaving the leaves for 48 hours

  
• Q5 (ii) The mass of Leaf A was 1.70 g at the start of the investigation. After 48 hours it was 1.38 g. Calculate the % decrease in mass over 48 hours.

  18.8%

  
• Q5 (c) Vaseline blocks the stomata. The % change in mass of Leaf B was less than Leaf A after 48 hours. Explain why.

  Less water loss since the vaseline blocks the stomata

  
• Q5 (d) Give three environmental conditions that would increase transpiration.

  1. Temperature
  2. Wind Speed
  3. Light intensity