Question

How do stomata open and close? Explain.

Accepted Answer

Stomata are the small opening present on the surface of the leaves. These pores are open during the day and almost closed during the night. Almost all gaseous exchanges in plants take place through stomata. The opening and closing of stomata are controlled by two kidney-shaped epidermal cells known as guard cells.

The mechanism of stomatal opening and closing:

The opening and closing of stomata is due to the change in turgor pressure of the guard cell. During the day the roots absorb water due to greater transpiration pull, and it is transported to different parts of the plant through the xylem. The guard cell on receiving this water swells and becomes turgid. As a result of which the stomatal pore is open. Thus, stomata open when the guard cells surrounding the stomatal pore become turgid.

At night, the roots absorb less water, thus the guard cell becomes flaccid and shrinks. As a result, the stomatal pores close. Thus, the stomata close when guard cells become flaccid due to water loss.

How do stomata open and close? Explain.

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