[Campbell Biology P.853] Why does photosynthesis primarily cease when plant leaves wilt, und... | Practice Question

Why does photosynthesis primarily cease when plant leaves wilt, under conditions of water deficiency?

  • A: The chlorophyll in wilting leaves is degraded.
  • B: Accumulation of CO2 in the leaf inhibits enzymes.
  • C: Stomata close, preventing CO2 from entering the leaf.
  • D: Photolysis, the water-splitting step of photosynthesis, cannot occur when there is a water deficiency.

Explanation

When plants experience water deficiency, they close their stomata to conserve water and prevent further transpiration. However, stomatal closure also prevents the uptake of carbon dioxide CO2 from the atmosphere, which is a crucial reactant for photosynthesis. Without sufficient CO2, the light-independent reactions of photosynthesis cannot proceed efficiently, leading to a cessation of the overall process.