Question

Which of the following theory gives the latest explanation for closure of stomata?

• A. ABA theory
• B. Munch theory
• C. Starch - glucose theory
• D. Active $K^{+}$ transport theory

Answer 1

The correct option is D Active $K^{+}$ transport theory

According to the most widely accepted view, stomata open or close due to turgor movement in guard cells. When guard cells gain water they swell and become turgid and stomata open. When guard cells lose water they become flaccid and stomata close.

The turgor movements in guard cells depend on the inflow and outflow of potassium ions. When potassium ions move inside guard cells, the water potential of guard cells decrease and they gain water and swell. When potassium ions move out the process is reversed.