Question

______ hormone is responsible for efflux of K\(^+\) ions from guard cells and acts as an antitranspirant.

• A. Gibberellins
• B. Cytokinin
• C. Ethylene
• D. Abscisic acid

Hint:

ABA is a stress hormone that helps plants conserve water under drought conditions by closing stomata.

Answer 1

The Correct Option is D

The question asks which hormone is responsible for the efflux of K\(^+\) ions from guard cells and acts as an antitranspirant. Let’s analyze the options and determine the correct answer.

1. Gibberellins: Gibberellins are a group of plant hormones that primarily promote growth and influence various developmental processes like seed germination, stem elongation, and flowering. They are not involved in the efflux of K\(^+\) ions from guard cells.
2. Cytokinin: Cytokinins are plant hormones that promote cell division, delay leaf senescence, and are generally involved in promoting cell growth and differentiation. They do not play a role in the efflux of K\(^+\) ions from guard cells or act as antitranspirants.
3. Ethylene: Ethylene is a gaseous hormone that regulates fruit ripening, leaf abscission, and flower wilting. It does not manage the efflux of K\(^+\) ions from guard cells.
4. Abscisic Acid (ABA): Abscisic acid is a plant hormone known for its role in stress responses. It helps the plant close stomata by influencing the efflux of K\(^+\) ions from guard cells, thereby reducing water loss through transpiration. This is why ABA is often considered an antitranspirant.

Based on these explanations, the correct answer is Abscisic Acid. Abscisic acid plays a crucial role in the water stress response and is responsible for signaling the efflux of K\(^+\) ions from guard cells to aid in the closing of stomata, thereby acting as an antitranspirant by reducing water loss.