Question

Glycolate induces opening of stomata in
A. Presence of oxygen
B. Low $C{O_2}$ concentration
C. High $C{O_2}$ concentration
D. Absence of $C{O_2}$

Answer 1

Stomata are the porous structures present on the leaf surface which are enclosed by a pair of curved tubular guard cells. It is believed that gaseous exchange takes place when the stomatal pores are open to facilitate photosynthesis. Let us try to understand a little more about it to find the correct answer.

Complete answer:
Let us first know about the effect of carbon dioxide on the opening of stomata.
So if we talk about the significance of stomata, plants breathe through these tiny pores and they are present underside of the leaves. Opening and closing of stomata are regulated in such a way so that an adequate amount of gaseous exchange occurs for the functioning and normal metabolism of plants. Effect of $C{O_2}$on the opening of stomata -
Carbon dioxide concentration- Plants seem to open and close their stomata in response to changes in carbon dioxide concentration and they open their stomata under conditions of low $C{O_2}$ so that the need for $C{O_2}$ is sufficed and dryness is avoided. It is believed that glycolic acid is synthesised under low $C{O_2}$ concentrations and that this glycolic acid serves as a precursor for carbohydrate synthesis in the guard cells. Thus, carbon dioxide concentration in the guard cells increases establishing osmotic pumps. This acid is also involved in a pump that utilises ATP called glyoxylate-glycolate shuttle. This ATP thus helps in the pumping of water into the guard cells by active process and this leads to stomatal opening.

Based on the above discussion, it is clear that the correct answer is (B).

Note:
Other than concentration of carbon dioxide, there are other factors also affecting the opening and closing of stomata. They are-
Light- red and blue light are effective for both photosynthesis and opening of stomata, with blue light having more predominant (as compared to red light) role in opening of stomata than in photosynthesis.
Epidermal cells water content- higher water concentration leads to build up of turgor pressure inside guard cells leading to opening of the stomata.
Temperature- it affects the permeability of the walls of guard cells and thus the osmotic phenomenon also gets affected. A higher temperature leads to stomatal opening.
Mineral elements- deficiency of certain minerals such as potassium, phosphorus, and nitrogen also affect closing and opening of stomata.