Biology Respiration / Gaseous Exchange MDCAT 2017
PMDC Verified Question 26 of 34
Respiratory tubules are termed as bronchioles when they attain the diameter of or lesser.
A
\( 1 \text{ mm} \)
B
\( 1.2 \text{ cm} \)
C
\( 1 \text{ cm} \)
D
\( 1.2 \text{ mm} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( 1 \text{ mm} \)
Concept: The respiratory tree is classified based on structural changes, particularly the presence or absence of cartilage and overall diameter.

Solution:
  • As the bronchi branch repeatedly, their diameter decreases and the cartilaginous rings are gradually replaced by irregular plates.
  • Once a tubule reaches a diameter of \( 1 \text{ mm} \) or less, it loses its cartilage entirely.
  • At this specific structural threshold, the passage is officially termed a bronchiole.


Why other options are incorrect:
  • \( 1.2 \text{ cm} \), \( 1 \text{ cm} \), \( 1.2 \text{ mm} \): These measurements are either too large (representing bronchi or the trachea) or slightly above the strict anatomical threshold for defining a bronchiole.

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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