Question

Which of the following is the function of stomata?
a. It controls the loss of food and material from the plants.
b. It helps in the transpiration.
c. It prevents exchanges of gases.
d. It controls the loss of energy from the plant.

Answer 1

Hint: Stomata are the minute structures generally found on the epidermal layers of leaves. They are absent in the epidermis of roots. Each stoma is composed of two kidney-shaped cells known as guard’s cells and a tiny stomatal pore.

Complete answer:
> Option A is incorrect because stomata only regulate the loss of water and exchanges of gases through the opening and closing of the stomatal pore. It does not regulate the loss of food and minerals.

> Option B is correct. Stomata regulate the process of transpiration. Transpiration is the loss of water through the process of evaporation in plants. When stomata are open the rate of transpiration increases, and when they are closed there is a decrease in the rate of transpiration.

> Option C is incorrect. It does not prevent the exchange of gases. The gaseous exchange involves the exchange of oxygen and carbon dioxide between plants and the environment. The loss of water and the exchange of gases occurs through stomata.

> Option D is also incorrect because stomata only control the loss of water and the exchange of gases, not energy.

Hence, the correct answer is option (B).

Additional information:
Usually, the lower surface of a dicotyledonous leaf has a greater number of stomata than the upper surface while in a monocotyledon leaf, they are about equal in number on both the surfaces.

Note: The stomatal pore is surrounded by guard cells that help in the opening and closing of the pore. When guard cells are turgid (swollen) the pore opens, and when they are flaccid (shrunken), the stomatal pore is closed. The walls of the guard cells towards the stomatal pore are called inner walls and away from the stomatal pore are called the outer walls. The outer walls of the guard cells are thin while the inner walls of the guard cells are thin.