Veterinary Microbiology- ICAR JRF/SRF 2024

• Substituted Phenols in Veterinary Medicine:
• Substituted phenolic anthelmintics act by uncoupling oxidative phosphorylation in helminth mitochondria:
• Bithionol: Dichlorophenolic compound.
• Hexachlorophene: Bisphenol derivative.
• Nitroxynil: Substituted monophenol ($4\text{-hydroxy-3-iodo-5-nitrobenzonitrile}$).
• Niclosamide:
• chlorinated Salicylanilide derivative (5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide), not classified chemically as a simple substituted phenol.
• nalysis:
• (Niclosamide): Correct.

Correct option: (3) Niclosamide

• Measurement of Residual Chlorine in Drinking Water:
• Chlorination of water leaves free residual chlorine ($HOCl, OCl^-$) to protect against recontamination.
• The Ortho-Tolidine (OT) Test:
• Ortho-tolidine reagent reacts instantly with free available chlorine to form a bright yellow compound (holoquinone of ortho-tolidine).
• Color development within 5–10 seconds quantifies free chlorine concentration colorimetrically.
• nalysis:
• (Ortho-toluidine test): Correct.

Correct option: (3) Ortho-toluidine test

• Stages in Municipal Rapid Sand Water Purification:

• Storage / Sedimentation (B): Raw water is stored to allow coarse suspended solids to settle.
• Coagulation and Flocculation (A): Chemical coagulants (alum) are added with rapid mixing to aggregate fine colloidal impurities into settleable flocs.
• Filtration (C): Water passes through a rapid gravity sand and gravel filter bed to remove remaining particulate matter.
• Chlorination (D): Terminal chemical disinfection (gaseous chlorine/bleaching powder) to destroy pathogenic microorganisms and provide residual protection.
  • Sequence:

• nalysis:
• ((B), (A), (C), (D)): Correct.

Correct option: (3) (B), (A), (C), (D)