How do the guard cells regulate

Opening and closing of stomata is regulated by gain or loss of turgidity of their guard cells. During opening of stomata, guard cells withdraw

K+ ions from surrounding epidermal cells, followed by absorption of water from them. As a result, guard cells swell up and become turgid. Their

outer thin and elastic walls bend outwardly followed by outward movement of thicker inner walls. The latter creates a pore in between the two

guard cells.

During closure movement of stomata, guard cells send out K+ ions. Water also passes out. Guard cells become flaccid. Their inner thick walls

come to touch each other. The stomatal pore gets closed.