Question

How do the guard cells regulate the opening and closing of stomata?

Answer 1

Through turgity of the guard cell regulates the opening and closing of stomata

Answer 2

The opening and closing of the stomata is controlled by the guard cells.

In light, guard cells take up water by osmosis and become turgid. Because their inner walls are rigid they are pulled apart, opening the pore. In darkness water is lost and the inner walls move together closing the pore.When guard cells are turgid, stomatal pores is open while in flaccid conditions the
stomatal aperture closes.