Biology Respiration / Gaseous Exchange MDCAT 2016
PMDC Verified Question 32 of 34
Breathing consists of:
A
Two phases
B
One phase
C
Three phases
D
Four phases
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Two phases
Concept: Breathing (pulmonary ventilation) is a cyclic, mechanical process driven by pressure gradients.

Solution:
  • Breathing strictly consists of two distinct phases:
  • 1. Inspiration (Inhalation): Active intake of air as thoracic volume increases and pressure decreases.
  • 2. Expiration (Exhalation): Passive (or forced) expulsion of air as thoracic volume decreases and pressure increases.


Why other options are incorrect:
  • Breathing is fundamentally a binary cycle of air moving in and air moving out. There are no tertiary or quaternary mechanical phases in standard pulmonary ventilation.

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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