Factors affecting photosynthesis

• Effect of changing light intensity on the Calvin cycle

  1. GP cannot be reduced to TP
  2. TP levels fall and GP accumulates
  3. If TP levels fall, RuBP cannot be generated
• Effect of changing the carbon dioxide concentration on the calvin cycle

  1. RuBP cannot accept it, and accumulates
  2. GP cannot be made
  3. therefore, TP cannot be made
• Temperature 


  • Calvin cycle involves many enzyme-catalysed reactions and therefore it is sensitive to temperature
  • temperatures above 45 degrees Celsius, enzymes involved in photosynthesis may be denatured. This would reduce the concentrations of GP and TP, eventually RuBP as it cant be regenerated due to lack of TP
• water stress

  Turgid guard cells keep stomata open for gas exchange

  if not enough water available for plant (water stress):

  • roots unable to take up enough water to replace that lost via transpiration
  • cells lose water and become plasmolysed
  • plant roots produce abscisic acid that, when translocated to leaves, causes stomata to close, reducing gas exchange
  • tissues become flaccid and leaves wilt
  • rate of photosynthesis greatly reduces
• light intensity

  
• effect of light intensity on calvin cycle

  
• effect of carbon dioxide concentration on calvin cycle