Multiple choice

Abscisic acid causes

  1. slow movement of water out of the guard cells

  2. slow movement of K+ out of the guard cells

  3. rapid movement of water out of the guard cells

  4. rapid movement of K+ out of the guard cells
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Abscisic acid (ABA) acts as a stress hormone that triggers stomatal closure. It does this by inhibiting H+ pumps and promoting the rapid efflux of K+ ions from guard cells, which leads to water loss and turgor reduction.

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