Question

According to active $K^{+}$ transport hypothesis, besides the organic acids, the turgidity of guard cells is controlled by which one of the following combinations of ions?

• A. $K^{+}$, $N{a}^{+}$, $C{l}^{-}$
• B. $K^{+}$, $N{a}^{+}$, $H^{+}$
• C. $K^{+}$, $H^{+}$, $C{l}^{-}$
• D. $K^{+}$, $N{a}^{+}$, $H^{+}$, $C{l}^{-}$

Answer 1

The correct option is C $K^{+}$, $H^{+}$, $C{l}^{-}$

According to the $K^{+}$ transport hypothesis, the opening of stomata depends on the following conditions:

1. Presence of light
   
2. Decrease in starch contents of guard cells
   
3. Increased concentration of malic acid in guard cells.
   
4. Influx of $K^{+}$ ions in guard cells.
   
5. Efflux of $H^{+}$ ions from guard cells.
   
6. Intake of $C{l}^{-}$ ions by guard cells
   
7. Low $C{O}_2$ concentration in and around guard cells.
   
8. High pH in guard cells.
   Thus, the correct answer is option (C).