Biology Respiration / Gaseous Exchange MDCAT 2017
PMDC Verified Question 28 of 34
Low partial pressure of oxygen in tissues favors ____ of oxyhaemoglobin.
A
Stability
B
Formation
C
Dissociation
D
Transformation
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Dissociation
Concept: The behavior of hemoglobin changes dynamically based on the partial pressures of gases in its surrounding environment (Oxygen-Hemoglobin Dissociation Curve).

Solution:
  • In the lungs, where the partial pressure of oxygen (\( \text{pO}_2 \)) is very high, hemoglobin's affinity for oxygen peaks, favoring the formation of oxyhemoglobin.
  • Conversely, at the tissue level, cellular respiration heavily consumes oxygen, resulting in a very low \( \text{pO}_2 \).
  • This low \( \text{pO}_2 \) triggers hemoglobin to lose its affinity and release its bound oxygen. This process is called dissociation.


Why other options are incorrect:
  • Formation / Stability: These are favored in high \( \text{pO}_2 \) environments (the lungs), ensuring oxygen gets securely loaded onto the RBCs.

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