Stomata are the special pore-like structure in the epidermis of plants. They occur mostly in leaves.
Each stomata is surrounded by two kidney shaped guard cells containing chloroplast, which the opening & closing of stomata and the inner wall of the guard cell is thick and inelastic due to presences of a secondary cellulose layer. The outer wall of the guard cell is thin, elastic and permeable.
The opening & closing of stomata depends upon the turgidity of their guard cells.
Stomata are open when the guard cells are turgid. The inner margins curve a part due to outward stretching of outer cells resulting in the acidifying of stomata pore.
Stomata are closed when the turgidity of guard cells decreases with the loss of turgidity the nine margins become straight and come close to each other which results in the closing of stomatal pore.
The changes in the turgidity of the guard cells control the opening & closing of stomata. The turgidity of a guard cell is regulated by concentration of solutes present in it which mainly depend upon the rate of photosynthesis. The system involved in the transportation of various substances within the blood of an animal is called circulatory system.
