Question

Match List I with List II
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Choose the correct answer from the options given below:

• A. A - II, B - III, C - IV, D - I
• B. A - IV, B - I, C - III, D - II
• C. A - IV, B - III, C - I, D - II
• D. A - II, B - IV, C - I, D - III

Hint:

- Glyphosate \(\rightarrow\) EPSP Synthase Inhibitor (Shikimate pathway).
- Metsulfuron \(\rightarrow\) ALS Inhibitor (Branched-chain amino acids).
- Clomazone \(\rightarrow\) Bleaching agent (Carotenoid inhibitor).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Herbicides are classified into distinct groups based on their chemical structure and their specific biochemical mechanism of action (how they disrupt plant growth).
Detailed Explanation:
Let us match each mechanism of action with its corresponding herbicide:
- A. Inhibition of EPSP synthase: EPSP synthase (5-enolpyruvylshikimate-3-phosphate synthase) is a key enzyme in the shikimate pathway, which is essential for synthesizing aromatic amino acids.
Glyphosate is a broad-spectrum, non-selective herbicide that specifically inhibits EPSP synthase.
This matches with IV. Glyphosate.
- B. Carotenoid biosynthesis inhibitor: Carotenoids protect chlorophyll from being destroyed by excess light.
Clomazone inhibits carotenoid synthesis, which causes the plant's leaves to turn white (bleaching).
This matches with I. Clomazone.
- C. ALS inhibitor: ALS (Acetolactate synthase) is a key enzyme needed to synthesize branched-chain amino acids (valine, leucine, and isoleucine).
Metsulfuron-methyl (a sulfonylurea herbicide) works by inhibiting the ALS enzyme.
This matches with III. Metsulfuron methyl.
- D. PPO inhibitor: PPO (Protoporphyrinogen oxidase) is an enzyme involved in chlorophyll synthesis.
Carfentrazone-ethyl inhibits PPO, leading to a buildup of toxic compounds that rupture cell membranes.
This matches with II. Carfentrazone.
Combining these pairs yields the sequence: \[ \text{A - IV}, \ \text{B - I}, \ \text{C - III}, \ \text{D - II} \] This matches Option (B).

Step 2: Final Answer:
The correct matching sequence is A - IV, B - I, C - III, D - II.