Question

Stomata open and close due to
A) Turgor pressure change
B) Hormonal change
C) Temperature change
D) All of the above

Answer 1

Hint:-A stoma also called a stomata is a pore, found in the epidermis of leaves, stems, and other organs that control the rate of gas exchange in plants. The pore is bordered by a pair of specialized parenchymatous cells called guard cells. These guard cells are responsible for regulating the size of the stomatal opening.

Complete Answer:-Leaves with stomata on the upper as well as the lower side of leaf are called amphistomatous leaves while leaves with stomata only on its lower surface are called hypostomatous, and leaves with stomata only on the upper surface are epistomatous and hyperstomatous. There are many factors which affect the movement of stomata are as follows:-
Soluble sugar product which is formed during photosynthesis decreases the water potential of guard cells and results in uptake of water by the guard cells from the adjacent subsidiary/epidermal cells. Thus, the guard cells become turgid and lead to the opening of stomata. During the night, the closing of the stomata takes place as the turgor pressure of guard cells decreases.
Cytokinins are essential for the opening of stomata while abscisic acid is responsible for the closing of stomata. Plants produce more abscisic acid which causes potassium ions to move out of guard cells and stomata close in response to water deficiency. Increase in temperature results in the increased extent of stomatal opening.

Hence, the correct option is (D) All of the above

Note:- Stomatal complex consists of the paired guard cells and the stomatal pore also referred to as the stomatal aperture. Air enters the plant through these openings by the process of gaseous diffusion of carbon dioxide (as used in photosynthesis) and oxygen (as used in respiration). Oxygen then produced as a by-product of photosynthesis diffuses out to the atmosphere through these openings. Water vapour also diffuses out through the stomata into the atmosphere during the process of transpiration.