stomatal opening and closing

• what is the first stage in the mechanism that opens the stomata


  potassium ions are actively transported from the epidermal cells into the guard cells
• what is needed for the activation of the potassium pumps to transport potassium into the guard cell


  light
• what happens after the potassium ions have moved into the guard cells


  starch in the guard cells is converted to malate by enzymes in the cytoplasm
• what happens after starch is converted into malate in the guard cells

  the water potential in the guard cell is lowered so water enters in via osmosis
• what happens to the cell once water has moved in by osmosis


  the guard cells become turgid and curve apart
• why is the stomata open during the day


  to allow carbon dioxide to diffuse into the leaf for photosynthesis
• why is the stomata closed at night


  to reduce water loss