Solution: Auxin is a growth hormone produced by the tryptophan-dependent auxin biosynthesis pathway, which uses tryptophan as a precursor. Zinc aids in the production of auxin and protects it from free radical oxidation. It serves as a coenzyme and activates the auxin-forming enzyme, suppressing the generation of oxygen during the synthesis of auxin. Plants with zinc deficiency show reduced biosynthesis of Auxin (IAA).