Q.49 Which of the following is/are synthetic auxin(s) that does/do NOT occur naturally?
(A) 2,4-Dichlorophenoxyacetic acid
(B) Indole-3-acetic acid
(C) Indole-3-butyric acid
(D) 1-Naphthaleneacetic acid
Synthetic Auxins in Plant Biology: Identifying 2,4-D and Natural vs. Synthetic Auxins
Indole-3-acetic acid (IAA) serves as the primary natural auxin in plants, while synthetic auxins like 2,4-D mimic its effects for agricultural use. In multiple-choice question Q.49, option (A) 2,4-Dichlorophenoxyacetic acid stands as the key synthetic auxin that does not occur naturally, distinguishing it from the others.
Correct Answer
(A) 2,4-Dichlorophenoxyacetic acid is the synthetic auxin that does NOT occur naturally.
Option Breakdown
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(A) 2,4-Dichlorophenoxyacetic acid: Developed as a herbicide, this compound mimics IAA but features chlorine substitutions, ensuring it arises solely from synthesis and never naturally in plants.
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(B) Indole-3-acetic acid: Known as IAA, this represents the main natural auxin produced endogenously in plant tissues like shoot apices and regulating growth processes.
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(C) Indole-3-butyric acid: IBA occurs naturally in plants at low levels and also gets synthesized for rooting hormones, blurring natural and artificial lines.
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(D) 1-Naphthaleneacetic acid: NAA exists naturally in some plants and proves widely synthesized for fruit setting and weed control applications.
