Question

During opening of stomata, influx of $K^+$ ions into the guard cells is accompanied with efflux of

• A. $Na^+$
• B. $K^+$
• C. $Cl^-$
• D. $H^+$

Answer 1

Answer: (D)

$H^+$

Answer 2

According to active $K^+$ ion transport theory, during day time, $CO_2$ concentration decreases due to it being used up in photosynthesis. Malic acid is formed in guard cells which dissociates into malate ions and $H^+$. $K^+$ ions exchange with $H^+$ ions from cytoplasm of guard cells.