Biology Immunity KMU 2024
PMDC Verified Question 61 of 99
What directly triggers the activation of natural killer cells?
A
Free radicals
B
Hydrogen peroxide
C
Oxygen
D
Interferons
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Interferons
Concept:

The innate immune system utilizes cytokine signaling to mobilize cellular defenses rapidly.

Formula:

None

Solution:

  • When a host cell is infected by a virus, it synthesizes and secretes warning proteins known as Interferons.


  • These interferons bind to receptors on nearby uninfected cells to boost their defenses.


  • Crucially, interferons act as a chemical distress beacon that directly stimulates and activates nearby Natural Killer (NK) cells to find and destroy the infected host cells.


Why other options are incorrect:

  • Free radicals, hydrogen peroxide, and oxygen are chemicals used during the "respiratory burst" by macrophages and neutrophils to digest phagocytosed bacteria, but they are not the signaling molecules that activate NK cells.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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