Question

The opening and closing of stomatal pore depends upon-
A. Oxygen
B. Wind velocity
C. Water in guard cells
D. Carbon Dioxide concentrations

Answer 1

Transpiration is the process that includes the loss of water from the plants into the surroundings in the form of water vapour. The transportation process takes place in the leaves of the plant.

Complete answer:
To answer this question, we first have to understand the structure of the stomata that helps in the transpiration process.
The stomata are found on the epidermal Surface of the leaves. It consists of two kidney-like structures known as the guard cells. The inner well of the guard cell is thicker as compared to the outer wall. There are microfibrils found in the guard cells that involve in the opening and closing of the stomatal aperture. The opening and closing of the stomata is a result of Chang in the turbidity in the guard cells. In the daytime the guard cells involved in the photosynthesis process as a result the osmotic pressure increases and the guard cells absorb the water contained from the neighboring cells that make the guard cells turgid. Then the outer well of the guard cells is pushed out and the inner wall pulls in the inward direction that causes the opening of the stomata. And during night due to unavailability or scarcity of water the stomata remain close as the guard cell becomes flaccid therefore we can say that the opening and closing of the stomatal pore depends upon the water in guard cells

Hence, the correct answer is option (C).

Note: The oxygen and the carbon dioxide exchange in the plants are carried out by osmosis process; it does not relate with the opening and closing of the guard cells. The wind velocity does not relate to the transportation process.