How do the guard cells regulate opening and closing of stomatal pores?

Q. How do the guard cells regulate opening and

closing of stomatal pores?

[CBSE 2013]

Ans. Stomata are tiny openings present on the

underside of the leaf. The stomatal openings

are surrounded two bean shaped cells. These

are called guard cells. The main function of the

guard cells is to control the opening and closing

of stomata. When water enters the guard cell, it

swells. This results in the opening of the guard cells.

On the other hand, the shrinking of the

guard cell results in the closing of the stomatal

opening.