NEET BIOLOGY

Detailed explanation-1: -Trp is a known precursor for auxin biosynthesis and it has been demonstrated that feeding plants with labeled Trp leads to the production of labeled IAA (Wright et al., 1991; Normanly et al., 1993).

Detailed explanation-2: -The major precursor of auxin is amino acid tryptophan from which auxin is synthesized through a certain metabolic pathway naturally. So, the correct answer ‘raw material used in the synthesis of auxin’

Detailed explanation-3: -Physiological and stable isotope labeling studies established that trp is a precursor for de novo IAA biosynthesis in plants.

Detailed explanation-4: -The Tryptophan-Dependent Auxin Biosynthesis Pathway. The first step is catalyzed by TAAs that transfer the amino group from Trp to an alpha keto acid such as pyruvate to generate IPA and another amino acid. The second step is an oxygen and NADPH-dependent reaction catalyzed by the YUC flavin-containing monooxygenases.