Biology Immunity PMDC Conceptual Practice
PMDC Verified Question 8 of 99
All of the following components act as physical or chemical barriers against microbial entry EXCEPT:
A
Red blood cells
B
Tears
C
Mucous membranes
D
Ciliated epithelial cells
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Red blood cells
Concept: First line of defense (innate barriers).

Solution: Red blood cells (erythrocytes) function in gas transport (oxygen and carbon dioxide) via hemoglobin and play no direct barrier role in preventing pathogen entry.

Why other options are incorrect:
  • Option B: Tears contain chemical barriers like lysozyme and provide flushing action.

  • Option C: Mucous membranes act as continuous physical barriers trapping microbes.

  • Option D: Ciliated epithelial cells form the mucociliary escalator to sweep pathogens out of respiratory passages.

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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