Biology Respiration / Gaseous Exchange ETEA 2022
PMDC Verified Question 17 of 34
The percentage of carbon dioxide carried as carboxyhaemoglobin is:
A
\( 70\% \)
B
\( 15\% \)
C
\( 7\% \)
D
\( 23\% \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 23\% \)
Concept: Carbon dioxide is managed by the cardiovascular system through three distinct transport mechanisms to maintain acid-base balance.

Solution:
  • \( \text{CO}_2 \) is distributed in the blood as follows:
  • 1. As bicarbonate ions (\( \text{HCO}_3^- \)): Approximately \( 70\% \) is converted via carbonic anhydrase.
  • 2. Bound to hemoglobin (carbaminohemoglobin): Approximately \( 23\% \) (often called carboxyhaemoglobin in older local syllabus).
  • 3. Dissolved in plasma: Approximately \( 7\% \) remains as a dissolved gas in the blood fluid.


Why other options are incorrect:
  • \( 70\% \): Represents the bicarbonate ion fraction.
  • \( 7\% \): Represents the dissolved plasma fraction.

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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