Zinc is essential for

A. Stomatal closing

B. biosynthesis of 3-IAA

C. Oxidation of carbohydrates

D. None of the above

Answer: Option B

Solution(By Examveda Team)

Zinc is essential for biosynthesis of 3-IAA in plants.
Zinc activates tryptophan synthetase, which regulates the synthesis of tryptophan, involved in the biosynthesis of indoleacetic acid (IAA).
Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best-known of the auxins and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, containing a carboxymethyl substituent.