Question

In photoactive plants, during daytime, the following ionic flux of guard cell directly involves the expenditure of energy

• A. outward movement of malate
• B. inward movement of $K^{+}$
• C. outward movement of protons
• D. inward movement of $C{l}^{-}$

Answer 1

Answer: (C)

outward movement of protons

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