Before You Begin
Question #46333
The Question
In a scenario of extreme tissue hypoxia, the absence of oxygen as the terminal electron acceptor in the mitochondrial Electron Transport Chain (ETC) triggers a cascade of metabolic and physiological shifts. Which of the following is NOT a correct consequence of this hypoxic state?
Options
- A.
The proton motive force across the inner mitochondrial membrane collapses, halting ATP synthesis via Complex V.
- B.
Pyruvic acid is reduced to lactic acid by lactate dehydrogenase, regenerating NAD+ to sustain the glycolytic pathway.
- C.
The resulting accumulation of H+ ions shifts the oxygen dissociation curve to the left, increasing hemoglobin's affinity for O2 to compensate for the hypoxia.
- D.
The acidic shift alters the tertiary structure of hemoglobin, reducing its O2 affinity and potentially exacerbating the hypoxic crisis.
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|Chemiosmotic ATP Synthesis Logic|Glycolysis Redox Balance
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The teleological trap.
Students often assume that during hypoxia, the body will 'compensate' by increasing hemoglobin's affinity for oxygen to grab more of it (a left shift).
However, the biochemical reality of lactic acidosis dictates a right shift (Bohr effect), which decreases affinity.
While beneficial for local tissue unloading, in severe systemic hypoxia, this decreased affinity impairs pulmonary oxygen loading, worsening the crisis.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Breathing and Exchange of Gases - Class 11 |
| Concept | Hemoglobin-CO2 Binding Sites |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |