Effect of Temperature

• Photochemical reactions of light dependent reactions aren’t very affected by temperature changes, but Calvin cycle’s enzyme catalysed reactions are very affected; between temperatures 0 to 25C, photosynthesis rate doubles for each 10C rise (Q10 = 2), above 25C, rate levels and then falls as more enzymes are denatured
• At higher temperatures, O_2 competes more successfully for rubisco active sites, reducing CO_2 fixation, also since it increases transpiration rate, plant stress response closes more stomata, limiting CO_2 uptake
• Temperature Graph

  A) low

  B) little

  C) limiting

  D) higher

  E) increases

  F) 20

  G) limiting