Question

What happens when the concentration of solutes decrease in the guard cells?

• A. Water potential decreases
• B. Water potential increases
• C. Osmotic potential increases
• D. None of the above

Answer 1

Answer: (B)

Water potential increases

The guard cells contain chloroplasts, so they can manufacture food by photosynthesis. It synthesizes glucose during the day time by the process of photosynthesis and so its water potential decreases 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 increase its water potential. The guard cell loses water and turns flaccid and the stomata closes, so the transpiration stops.

So, the correct answer is option B.