Select the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only.)
Assertion (A): Abscisic acid promotes stomatal closure during a drought. Reason (R): Abscisic acid helps the plant to conserve water during stress.
Topic: Assertion-Reason — abscisic acid
Try it
Pick an option and check your answer. The full worked answer is below either way.
Answer
(c) Both (A) and (R) are true and (R) is the correct explanation of (A).
BOTH STATEMENTS ARE TRUE, and the reason does explain the assertion.
Abscisic acid (ABA) is the plant’s stress hormone. When the soil dries, ABA accumulates in the leaf and acts on the guard cells, which lose water, become flaccid and close the stomata. Closed stomata mean very little transpiration, so the plant retains the water it still has.
WHY (C) AND NOT (D): the reason must answer the question "why does ABA close the stomata?" — and it does. Closure IS the mechanism by which water is conserved; the two statements are cause and purpose of the same action, not two separate facts.
Contrast this with part (iii) of this same paper, where the reason was about a different adaptation altogether. That is the distinction between options (C) and (D), and papers set both in the same question to test it.
ABA is also called the stress hormone or the dormancy hormone, and it promotes leaf fall and seed dormancy.
Both (A) and (R) are true and (R) is the correct explanation of (A).