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Question #46307
The Question
During extreme physical exertion, white muscle fibers rapidly accumulate lactic acid, causing a significant drop in local tissue pH. Despite this creating a pronounced Bohr effect and a steepened partial pressure gradient for between the systemic capillaries and the tissue, the muscle continues to rely heavily on anaerobic metabolism. Which of the following best explains this physiological limitation?
Options
- A.
The decreased pH shifts the oxygen dissociation curve to the left, inhibiting unloading at the tissue level.
- B.
Intense muscular contractions compress local capillaries, compromising tissue perfusion and rendering the favorable gradient ineffective.
- C.
White muscle fibers contain abundant myoglobin that tightly binds the unloaded , preventing its entry into the mitochondria.
- D.
The high concentration of lactic acid competitively inhibits the diffusion of across the endothelial membrane of the capillaries.
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
Red vs. White Muscle Fibers|Partial Pressure Gradient Logic|Bohr Effect
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that a favorable partial pressure gradient and a right-shifted Bohr curve automatically guarantee increased oxygen delivery.
They fail to account for the mechanical constraints of Fick's Law of Diffusion in vivo—specifically, that intense sustained contractions physically compress capillaries, limiting perfusion regardless of the chemical gradients.
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 |