Biology Respiration / Gaseous Exchange SZABMU 2024 Reconduct
PMDC Verified Question 6 of 34
Which of the following proteins are involved in the expansion and recoiling of alveoli during breathing?
A
Collagen and keratin
B
Collagen and elastin
C
Elastin and keratin
D
Collagens and squamous cells
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Collagen and elastin
Concept: The lung parenchyma must possess both structural integrity to prevent tearing and extreme elasticity to drive passive exhalation.

Solution:
  • The connective tissue walls of the alveoli are reinforced with two vital proteins:
  • Collagen: Provides tensile strength, preventing the alveoli from over-inflating or tearing.
  • Elastin: Acts like molecular rubber bands, allowing the alveoli to stretch easily during inspiration and snap back (recoil) effortlessly during exhalation, pushing air out.


Why other options are incorrect:
  • Keratin: A tough, waterproof protein found in hair, nails, and epidermis. It has absolutely no place in the delicate alveoli.
  • Squamous cells: These are epithelial cells, not proteins.

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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