Question

When the guard cells swell due to the entry of water, stomata gets ______ due to the osmotic potential
A. Closed
B. Flaccid
C. Open
D. Rigid

Answer 1

Hint: Guard cells are particular types of plant cells in the epidermis of leaves, stems and other organs that are used to control gas exchange.
They are produced in pairs with a space between them that make up a stomatal pore.
The stomatal pores are largest when water is freely available to them and by this guard cells become turgid, and closed when water availability is seriously low and then guard cells become flaccid.

Complete answer:
Stomata are tiny or small openings in plant tissue that helps in the exchange of gases. Stomata are normally found in the leaves of plants but sometimes in the stem of plants also. Guard cells surround the stomata and they regulate the opening and closing of stomatal pores. Opening and closure of the stomatal pore are mediated by two guard cells by maintaining the turgor pressure between them.
Guard cells regulate the turgor pressure by the movement of a large number of ions and sugars in and out. When guard cells consume these solutes, the water potential inside the cells decreases and leads osmotic water flow into the guard cells. This leads to a turgor pressure increase causing swelling of the guard cells and the stomatal pores open.

So, the correct option is option C.Open.

Note: Carbon dioxide, a key reactant in photosynthesis, is present in the atmosphere at a concentration of about 400 ppm. Most plants require the stomata to be open during daytime. The air spaces in the leaf are saturated with water vapour, which removes from the leaf through the stomata in a process known as transpiration.