Question

What are gard cells ? Explain their role in negulating transpiration ?

Answer 1

Stomata generally remains covered from both sides by a pair of chloroplast containing cells called guard cells. The opening and closing of stomata are determined by the size, shape and structure of the guard cells as influenced by the changes in their water content. When guard cells are turgid (high water content) their thin outer walls become convex and bulge out so that their inner walls are drawn out causing opening of stomata. If guard cells lose water, they become flaccid and their walls come back to the original position causing closing of stomata. In dicot plants guard cells are kidney shaped and in monocot plants guard cells are dumb-bell shaped.