Question

Opening and closing of stomata is controlled by
A. Abscisic acid
B. \[C{O_2}\] concentration
C. Light intensity
D. All of the above.

Answer 1

Hint: Stomata is also called a stoma, and it is a small pore or opening present in the surface of leaves, stems, etc and the main purpose is for the exchange of gases, and the border of the stomata is covered by parenchyma cells named as guard cells, which controls the opening and closing of the stomata.

Complete answer:
The term stoma is a collective structure that includes the pair of the guard cells, and the opening or aperture of the stomata.
The main function of the stomata is to exchange the gases that are carbon dioxide that is used for photosynthesis, and oxygen for respiration is exchanged, and the byproduct of photosynthesis is oxygen. And the water vapor exchange also takes place by a process called transpiration.
Opening and closing of stomata are controlled by the light intensity, humidity, and carbon dioxide concentration.
When the root sense of the plants occurs, in case of any shortage of water, then the release of Abscisic acid, which controls the stomatal closing.
The high light intensity, high humidity cause the proton pumps to the guard cells, and the electric potential becomes more negative, this causes potassium ion uptake and in turn causes the water diffusion, which increases cell volume and turgor pressure that cause the opening.
The Abscisic acid when released binds to guard cells and raises the PH so that electric voltage gradients and water osmosis occurs which controls the closing of stomata.

So from the all above given options, all of the above is correct for this question.

Note: Drought increases the stomatal opening, and the high light intensity, especially the presence of blue light and green light affects the stomata, and also low humidity stress also causes turgor loss. and cause the closure of the stomata, which is called as hydropassive closing of the stomata.