Stomata in grass leaf are
A. Rectangular
B. Dumb-bell shaped
C. Barrel shaped
D. Kidney shaped

Hint:They are pores in the leaves that regulate the exchange of gases and also control the rate of water vapour leaving the plants.

Complete answer:
Stomata are tiny openings or pores that enable gaseous exchange. Stomata are usually found in plant leaves, but they can also be found in some stems. When it does not need carbon dioxide for photosynthesis, the plant closes these pores.

The stomata in plants are enclosed by bean shaped cells called guard cells. The opening and closing of the pore is regulated by the guard cells. As water flows through them, the guard cells swell allowing the stomatal pore to expand. The pore often closes as the guard cells shrink. Apart from water vapour loss in transpiration, exchange of oxygen and carbon dioxide in the leaf also occurs through these stomata. Stomata are usually open in daytime and close at night.

While the form of most guard cells is bean-shaped, the grass has distinct stomata, consisting of two dumbbell-shaped guard cells joined by two lateral subsidiary cells (SCs). This is connected with quicker movement of stomata contributing to more water-efficient gas exchange in changing environments. Grasses have their stomata in ordered rows extending down the length of the leaf.

Thus, the correct answer is dumb-bell shaped.

Note: Stomata play a crucial role in the growth of plants by managing the exchange of gas with the environment and controlling transpiration. Various factors can influence its shape and size, efficiently regulating the uptake of water, transport and distribution of nutrients and hormonal signals in the various plant organs, thereby controlling growth.