Question

Match the plant growth hormone with its primary chemical nature: 

Column I		Column II
P	\(\text{Auxin}\)	1	\(\text{Simple gaseous hydrocarbon}\)
Q	\(\text{Gibberellin}\)	2	\(\text{Tryptophan is the primary precursor}\)
R	\(\text{Ethylene}\)	3	\(\text{15-carbon sesquiterpenoid}\)
S	\(\text{Abscisic Acid}\)	4	\(\text{Cyclic diterpene / Mevalonic acid precursor}\)

Choose the correct answer from the options given below:

• A. P-2, Q-4, R-1, S-3
• B. P-4, Q-2, R-1, S-3
• C. P-2, Q-1, R-4, S-3
• D. P-3, Q-4, R-1, S-2

Hint:

Key Exam Tip:
Learn the fundamental chemical classifications of plant hormones: Auxins (indole derivatives from tryptophan), Gibberellins (diterpenoids), Ethylene (gas), and Abscisic Acid (sesquiterpenoid).

Answer 1

The Correct Option is A

Let's establish the correct matches based on the chemical nature of these plant hormones: P. Auxin: The primary natural auxin, Indole-3-acetic acid (IAA), is synthesized from the amino acid tryptophan. Thus, P matches with 2. Q. Gibberellin: Gibberellins are a class of diterpenoid compounds. Their biosynthesis involves pathways that begin with mevalonic acid and lead to the formation of cyclic diterpenes. Thus, Q matches with 4. R. Ethylene: Ethylene is a plant hormone that is a simple gaseous hydrocarbon with the chemical formula $\text{C}_2\text{H}_4$. Thus, R matches with 1. S. Abscisic Acid (ABA): Abscisic acid belongs to the class of carotenoids and is chemically a 15-carbon sesquiterpenoid. Thus, S matches with 3. Therefore, the correct pairings are: P-2, Q-4, R-1, S-3. This corresponds to option (A). Final Answer: \(\boxed{A}\)