Question

Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening, carbon dioxide diffuses into the plant during photosynthesis. Reason out of the above statements using one of the following options.
A. Both processes cannot happen simultaneously.
B. Both processes can happen together because the diffusion coefficient of water and $CO_2$ is different.
C. The above processes can only happen during night time.
D. One process happens during the day and other at night time.

Answer 1

In the gaseous exchange between the plant and the atmosphere, stomatal opening and closing assist. It also assists in the form of water vapour in the transpiration and elimination of waste water. Both the processes are different. It retains the moisture balance by opening and closing, depending on the season.

Complete Answer:
The tiny holes found on the epidermis of the leaves are stomata. Under the light microscope, we will see stomata. Stomata are found on stems and other plant sections of some of the species. 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-
- An independent mechanism is the diffusion of water vapour and $CO_2$. In the atmosphere and within the leaves, their diffusion depends on the difference in their partial pressure.
- Both processes may exist together since there is a difference in diffusion coefficient of water and $CO_2$.

Hence the correct answer is option B.

Note: The opening and closure of stomata relies on the pressure of the turgor induced by the osmotic flow of the guard cells to the water. They expand while the guard cells are turgid, leading in the opening of stomata. When the guard cells lose water the stomatal becomes close because it becomes flaccid. When the lights hit the leaf, stomata usually open and close throughout the night.