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🔬 Biology  ·  Microbes in Human Welfare  ·  NEET

The immunosuppressive action of cyclosporin A involves inhibiting which cellular pathway in T lymphocytes?

Answer: The calcineurin-NFAT pathway, preventing cytokine gene transcription.

  • A The mTOR signaling pathway that governs T-cell growth and proliferation
  • B The calcineurin-NFAT pathway, preventing cytokine gene transcription
  • C The JAK-STAT pathway responsible for interferon-mediated signaling
  • D The NF-kB pathway that mediates the broader inflammatory response

Correct answer: B. The calcineurin-NFAT pathway, preventing cytokine gene transcription

Explanation: Cyclosporin A binds to cyclophilin, and this complex inhibits calcineurin phosphatase, which normally activates NFAT (Nuclear Factor of Activated T cells) to transcribe cytokine genes (like IL-2), thereby suppressing T cell activation and immune rejection.

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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