Question

Latest explanation for closure of stomata is

• A. Starch glucose theory
• B. Active $K^{+}$ ions theory
• C. ABA theory
• D. None of the above

Answer 1

Answer: (C)

ABA theory

There are many theories regarding the closure of stomata. The latest explanation is ABA theory according to which ABA (abscisic acid) blocks the uptake of potassium ions by guard cells on dark. It also prevents efflux of hydrogen ions from the guard cells. ABA helps in lowering the pH in guard cells and making the acidic medium. This helps in the closing of the stomata.

So, the correct answer is 'ABA theory'.