Question

Why do guard cells of the stomata have thicker walls inside and thinner walls on the outside surface ?

Answer 1

The inner walls of the guard cells are thick to facilitate the opening of the stomatal pore during transpiration and exchange of gases. The outer walls are thin and elastic.When the water enters inside the guard cell, the outer cells will be able to expand but not the inner walls. When the outer walls expand, bulge out and become convex, the inner walls will be drawn out causing the opening of stomata.