Question

Which of the following is a stress hormone?

• A. Ethylene
• B. G.A.3
• C. I.A.A.
• D. Abscisic acid

Hint:

Abscisic acid helps plants manage stress, such as by closing stomata to prevent water loss.

Answer 1

The Correct Option is D

Step 1: Understand plant stress hormones.
Abscisic acid (ABA) is the primary stress hormone in plants that helps them respond to environmental stress such as drought and salinity.
Step 2: Review the options.
- Ethylene is a hormone involved in fruit ripening and stress responses but not directly a "stress" hormone.
- G.A.3 (Gibberellic acid) is involved in growth and development, not stress responses.
- I.A.A. (Indole-3-acetic acid) is a plant growth regulator, not a stress hormone.
- Abscisic acid (ABA) is the correct stress hormone, as it is involved in stress adaptation and regulation of processes like stomatal closure under drought conditions.
Step 3: Conclude.
Abscisic acid (ABA) is the stress hormone in plants, making option (D) the correct answer.
Final Answer: \[ \boxed{\text{Abscisic acid}} \]