Botany - Transport in Plants Question with Solution | TestHub

The immediate cause of the opening or closing of stomata is a change in the turgidity of the guard cells. During opening, pH of the guard cell decreases,$PEP$case becomes functional,$PEP$forms malic acid which dissociates into H⁺  and malate ion and K⁺–H⁺pump causes accumulation of K⁺in guards cell, increasing its turgor pressure.