How do the guard cells regulate opening and closing of stomatal pores ?

Explanation

Opening and Closing of Stomata Opening and closing of stomata is an important event in the process of photosynthesis . Along with gaseous exchange, large amount of water can also be lost through stomata. So, plants close stomata when they does not need carbon dioxide. Each stoma is bounded by two kidney -shaped guard cells.
The opening and closing of stoma is resulted due to the turgidity of these guard cells. When the guard cells take up water and become turgid, the stoma opens and when guard cells lose water and shirnk , it closes.

The ends of two guard cells are joined and thin outer wall bends more readily than the thick inner one. These play an important part in opening and closing of stomatal pore.