Biology Respiration / Gaseous Exchange ETEA 2023
PMDC Verified Question 10 of 34
Which of the following statements is not correct about alveoli:
A
Alveoli form the gas exchange surface
B
Alveoli has a dense network of capillaries
C
The wall of each alveolus is \( 0.1 \text{ cm} \) thick
D
Collagen and elastin present in alveoli allow it to expand and recoil easily during breathing
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: The wall of each alveolus is \( 0.1 \text{ cm} \) thick
Concept: The physics of diffusion demand that respiratory surfaces be phenomenally thin. Misunderstanding biological units reveals conceptual errors.

Solution:
  • The wall of an alveolus is roughly \( 0.1 \, \mu\text{m} \) (micrometers) thick, not \( 0.1 \text{ cm} \).
  • \( 0.1 \text{ cm} \) is equal to \( 1 \text{ mm} \). A barrier \( 1 \text{ mm} \) thick would be an impenetrable fortress to gas diffusion, instantly causing asphyxiation.
  • Therefore, the statement claiming a \( 0.1 \text{ cm} \) thickness is mathematically and biologically completely incorrect.


Why other options are incorrect:
  • Dense capillary network, Gas exchange surface, Collagen/elastin presence: All of these are highly accurate biological facts regarding alveolar structure and function.

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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