Question

Basis for stomatal opening is

• A. Exosmosis
• B. Endosmosis
• C. Decrease in cell sap concentration
• D. Plasmolysis in guard cell

Answer 1

The correct option is B Endosmosis

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 by the process of endosmosis and turns turgid. Thus, stomata opens and transpiration takes place.

So, the correct answer is option B.