Question

Ionic flux of guard cells directly connected with expenditure of energy is

• A. Outward movement of protons
• B. Outward movement of malate
• C. Inward movement of $K^{+}$
• D. Inward movement of $Cl$

Answer 1

The correct option is A Outward movement of protons

Ions move in and out of the guard cells during stomatal closure and opening, depending on the proton pumping of the ATPase. It provides the proton gradient which is coupled to other secondary active transport mechanisms for $K^{+}andC{l}^{-}$. The outward movement of protons is directly involved in the expenditure of energy.

So the correct answer is option A.