2003 AIPMT Mineral NutritionRole of Zinc Easy Question 54 of 63 in Mineral Nutrition

Plants deficient of element zinc, show its effect on the biosynthesis of plant growth hormone -

A Auxin
B Cytokinin
C Ethylene
D Abscissic acid

The answer is A.

Solution

Zinc is needed for the synthesis of the amino acid tryptophan, which is the precursor of the auxin indole-3-acetic acid (IAA).
So zinc deficiency reduces auxin production. This causes stunted growth with short internodes and small leaves ('little leaf' and rosette diseases).
Zinc also activates enzymes such as carboxylases and alcohol dehydrogenase.
So zinc deficiency affects the biosynthesis of auxin.

Concept Zinc needed for auxin synthesis

Mineral Nutrition in past papers

63 questions from this chapter have appeared across 23 exam years.