Q. Select the correct events leading to the opening of the stomata. I.Decline in guard cell solutes. II.Lowering of osmotic potential of guard cells. III.Rise in potassium levels in guard cells. IV.Movement of water from neighbouring cells into guard cells. V.Guard cells becoming flaccid.
A) I and V
B) II, III and IV
C) I, III and IV
D) II, IV and V
Explanation
Levitt (1974) proposed ATP-driven $H^{+} - K^{+}$ exchange pump mechanism in guard cells for the stomatal opening and closing. According to it, there is accumulation of $K^{+}$ ions in the guard cells during day time. When guard cells possess more $K^{+}$, endosmosis takes place lowering the osmotic potential of guard cells, they become turgid and stomatal opening takes place.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.