42. Which hormone play important role in water stress in plants?
(1) Abscisic acid                (2) Ethylene
(3) Gibberellic acid            (4) Auxin

Correct answer: (1) Abscisic acid

Explanation:

• Abscisic acid (ABA) is the primary plant hormone involved in the response to water stress.

• ABA triggers stomatal closure to reduce water loss through transpiration during drought. It also regulates the expression of stress-responsive genes to help plants survive adverse conditions.

• Ethylene is involved in senescence and stress but not the primary hormone for water stress regulation.

• Gibberellic acid promotes growth and germination and typically acts antagonistically to ABA.

• Auxin mainly regulates growth and development, not direct water stress responses.

Option-wise:

• (1) Abscisic acid — correct; central regulator of water stress response.

• (2) Ethylene — involved in stress but less central for water stress.

• (3) Gibberellic acid — growth promoter, generally opposing stress inhibition.

• (4) Auxin — growth hormone, not water stress regulator.

  Abscisic acid is vital for plant survival under drought and water deficit conditions, controlling physiological and molecular responses that conserve water and protect plant cells from damage.