Question

Choose the correct sequence

• A. Chrysanthemum cinerariaefolium $\rightarrow$ Pyrethrins $\rightarrow$ Insecticide
• B. Streptomyces griseus $\rightarrow$ Streptomycin $\rightarrow$ Nematicide
• C. Streptomyces griseochromogenes $\rightarrow$ Blasticidin $\rightarrow$ Insecticide
• D. Streptomyces griseochromogenes $\rightarrow$ Blasticidin $\rightarrow$ Herbicide

Hint:

Pyrethrins are natural organic compounds that target the nervous systems of insects by keeping sodium channels open.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Many natural secondary metabolites extracted from plants or microbes are used commercially as agrochemicals (insecticides, bactericides, or fungicides).

Step 2: Detailed Explanation:
- Sequence 1 is correct: The dried flower heads of Chrysanthemum cinerariaefolium contain active esters called pyrethrins.
These compounds are widely extracted and used as natural, fast-acting organic insecticides.
- Sequence 2 is incorrect: Streptomyces griseus produces the antibiotic streptomycin, which is used as a bactericide, not a nematicide.
- Sequences 3 and 4 are incorrect: Streptomyces griseochromogenes produces Blasticidin-S, which is an antifungal antibiotic used to control rice blast disease, not an insecticide or herbicide.

Step 3: Final Answer:
The correct sequence is Chrysanthemum cinerariaefolium $\rightarrow$ Pyrethrins $\rightarrow$ Insecticide.