Question

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

Answer 1

The closing and opening of the stomata rely on the pressure that is caused by the water's osmotic flow in the guard cells. Cytokinins and abscisic acid help in opening and closing of stomata.

Complete answer:
One of the vital parts of plants that are used for gaseous exchange is stomata. Thousands of stomata are found on the leaves' surface. Many of these are located in the leaves on the lower side. The tiny openings found on the epidermis of the leaves are stomata. Stomata are found on stems and other plant sections. During gaseous exchange and photosynthesis, stomata play a significant role. By opening and closing, they regulate the rate of transpiration.
Now, let us find the solution from the options-

Option A: Photosynthesis happens in the guard cells during the daytime because they comprise chloroplasts. The soluble sugar provided by this process lowers the water potential of the guard cells, resulting in water absorption from the adjacent subsidiary or epidermal cells by the guard cells. The guard cells thus become turgid and open stomata. The reverse mechanism happens during the night which ends in the closure of stomata as the turgor pressure of guard cells reduces.
Option B: For the opening of stomata, cytokinins are important while abscisic acid participates in the closure of stomata. Plants respond to water scarcity b y generating more abscisic acid, which allows potassium ions to pass out of guard cells and close stomata
Option C: The increased stomatal opening results due to rise in temperature. In some plants , for example, Camellia stomata do not open even in bright light at very low temperatures i.e., below 0 ° C, although in some plants, stomata stay close to high temperatures .e., above 30 ° C.

Thus, the correct answer is option (D) All of the above.

Note: The main functions of stomata are transpiration, it also prevents water from escaping by closing the stomata, and it helps in maintaining moisture balance.