Question

how stomata is useful to the plants by exchange of food or exchange of gases

Answer 1

Answer:

The stomata control gas exchange in the leaf. Each stoma can be open or closed, depending on how turgid its guard cells are. In the light, the guard cells absorb water by osmosis , become turgid and the stoma opens. In the dark, the guard cells lose water, become flaccid and the stoma closes.

Answer 2

Answer:

Air enters the plant through these openings by gaseous diffusion, containing carbon dioxide which is used in photosynthesis. Also, water vapour diffuses through the stomata into the atmosphere in a process called transpiration.