Question

Explain mechanism of closing and opening of stomata.

Answer 1

Stomata are small openings present in various places on the surface of leaves through which exchange of gases take place. 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 their thin outer walls become convex and bulge out so that their inner walls are drawn out causing opening of stomata.

Answer 2

The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Simillarly the pore closes if the guard cells shrink