Question

Which one of the following growth regulators is known as ‘stress hormone’?

• A. Ethylene
• B. GA₃
• C. Indole acetic acid
• D. Abscisic acid

Answer 1

The Correct Option is D

The question asks us to identify the plant growth regulator known as the "stress hormone." This question is centered around understanding the functions and roles of different plant growth regulators.

Let's analyze each option to determine which is the correct answer:

1. Ethylene: Ethylene is a gaseous plant hormone involved in various processes such as fruit ripening, flower wilting, and leaf fall. It is not primarily known as a stress hormone.
2. GA₃ (Gibberellic Acid): Gibberellic acid is part of the gibberellin group of hormones, which promote growth and are crucial in seed germination and stem elongation. It does not function as a stress hormone.
3. Indole Acetic Acid (IAA): IAA is the most common natural auxin, a class of hormones that primarily regulate cell elongation and are instrumental in processes like phototropism and gravitropism. It is not related to stress response.
4. Abscisic Acid: Abscisic acid (ABA) is a plant hormone that plays an essential role in growth retardation and is directly associated with stress responses, particularly in closing stomata in response to drought stress. It helps the plant adapt to environmental stress conditions, thus termed as the "stress hormone."

Upon reviewing the options, Abscisic Acid is identified as the correct answer. It is widely recognized as the "stress hormone" because of its critical role in mediating plant responses to stress conditions like drought, salt, and cold stress.

Therefore, the correct answer is Abscisic Acid.