Transpiration is regulated by movement of A) Guard cells B) Subsidiary cell C) Epidermal cell D) Mesophyll cells
Option A) Transpiration is regulated by movement of guard cell. The guard cells contain chloroplasts, so they can manufacture food by photosynthesis. The epidermal cells don't have chloroplast. Due to the presence of chloroplast, guard cell synthesizes glucose during the day time by the process of photosynthesis and so its osmotic potential increases and it withdraws water from the epidermal cell and turns turgid and the stomata opens and transpiration takes place. At night, when there is no light the amount of solute decreases in guard cell which leads to fall in its osmotic potential. The guard cell loses water and turns flaccid and the stomata closes, so the transpiration stops.
