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🔬 Biology  ·  Microbes in Human Welfare  ·  NEET

Statins produced by Monascus purpureus lower cholesterol by which specific mechanism?

Answer: Competitively inhibiting HMG-CoA reductase, a key enzyme in cholesterol biosynthesis.

  • A Increasing hepatic bile acid production specifically to eliminate excess circulating cholesterol
  • B Competitively inhibiting HMG-CoA reductase, a key enzyme in cholesterol biosynthesis
  • C Blocking intestinal absorption of dietary cholesterol directly from ingested food sources
  • D Enhancing LDL receptor expression mainly within liver cell membranes specifically

Correct answer: B. Competitively inhibiting HMG-CoA reductase, a key enzyme in cholesterol biosynthesis

Explanation: Statins competitively inhibit HMG-CoA reductase (3-hydroxy-3-methylglutaryl coenzyme A reductase), the rate-limiting enzyme in the mevalonate pathway for cholesterol biosynthesis in the liver.

Sewage Treatment FlowPrimaryphysical filtering+ sedimentationSecondary (aerobic)aeration tank, flocsconsume organic matterActivated sludgesettles out;part reused as inoculumSludge digesterANAEROBIC →biogas (CH₄)Note the switch: aerobic microbes in the tank, anaerobic microbes in the digester

Sewage passes through physical removal (primary), then aerobic biological treatment where microbes form flocs that consume organic matter (secondary); the settled activated sludge is then digested anaerobically to produce biogas - a deliberate switch from aerobic to anaerobic conditions between stages.

Concept context

Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers

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