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Question #46304
The Question
In a case of severe carbon monoxide (CO) poisoning, a patient experiences acute tissue hypoxia even though their alveolar remains normal. Beyond merely reducing the number of available oxygen-binding sites, which of the following best explains the primary mechanism behind this severe tissue asphyxiation?
Options
- A.
CO binds to hemoglobin with high affinity, shifting the oxygen-dissociation curve to the right and promoting premature release in the arteries.
- B.
The formation of carboxyhemoglobin shifts the oxygen-dissociation curve to the left, preventing the unloading of bound at the tissue level despite low local .
- C.
CO competitively binds to the allosteric site of hemoglobin, mimicking the Bohr effect and drastically reducing oxygen uptake in the pulmonary capillaries.
- D.
CO directly inhibits the diffusion of across the respiratory membrane, leading to a massive drop in dissolved arterial .
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Hemoglobin-CO2 Binding Sites|Partial Pressure Gradient Logic|Alveolar Exchange
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume CO poisoning causes hypoxia solely by occupying binding sites (competitive inhibition).
The critical 'Plus-level' concept is the allosteric effect: CO binding increases the affinity of the remaining sites for , causing a left shift in the dissociation curve.
This traps on the hemoglobin, preventing tissue unloading.
A common trap is confusing the direction of the curve shift (Left = Locking , Right = Releasing ).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Breathing and Exchange of Gases - Class 11 |
| Concept | Partial Pressure Gradient Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |