Question

Which one is an antitranspirant hormone?

• A. Auxin
• B. Cytokinin
• C. Gibberellin
• D. Abscisic acid

Answer 1

The correct option is D

Abscisic acid

The correct option is D.

Explanation of correct option:

1. The process of loss of water in the form of water vapors, which generally takes place in the aerial parts of a plant is transpiration.
2. Transpiration is an essential phenomenon as it helps in the absorption of water and nutrients by the plants and helps the plant to remain cool.
3. However, in stress conditions like drought or water scarcity in the soil, there is a need to reduce the rate of transpiration.
4. Transpiration is primarily regulated by the presence of pores on the surface of the leaves, that is, stomata.
5. During stress, a plant hormone, that is, ABA or abscisic acid, which is a plant growth regulator encourages the closure of stomata.
6. This closing of stomata diminishes the rate of transpiration and enhances the water stress resistance capacity of the plant.
7. Thus, ABA is considered the antitranspirant hormone.

Explanation of incorrect options:

Option A:

A plant growth regulator, which is accountable for light-sensitive growth of the stem, embryo development, apical dominance, etc. is auxin.

Option B:

A plant growth regulator, which is mainly accountable for leaf senescence and cell division in plants is cytokinin.

Option D:

A plant hormone, which is mainly accountable for many developmental procedures like stem elongation, seed germination, floral development, and stem elongation in young plants is gibberellin.

Final answer: Abscisic acid is an antitranspirant hormone.