Before You Begin
Question #45462
The Question
When a lowlander ascends to high altitudes (>3500m), physiological acclimatization occurs primarily through increased erythropoietin (EPO) production and a decrease in the binding affinity of hemoglobin. However, native high-altitude populations (e.g., Tibetans) exhibit a paradoxical evolutionary adaptation. Which of the following best describes their genetic adaptation and its physiological rationale?
Options
- A.
Continuous hyper-secretion of EPO due to an up-regulated HIF (Hypoxia-Inducible Factor) pathway to maximize oxygen carrying capacity.
- B.
Down-regulation of the EPO response to hypoxia via genetic shifts, preventing blood hyperviscosity and pulmonary hypertension.
- C.
An evolutionary shift towards increased hemoglobin-oxygen binding affinity, ensuring maximum saturation in the alveoli.
- D.
Complete suppression of the bone marrow's response to EPO, relying entirely on an increased breathing rate and expanded lung capacity.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Erythropoietin|Co-evolutionary_Resistance|Diversity-Stability_Relationship
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Differentiating between short-term physiological acclimatization (increased EPO/RBCs) and long-term evolutionary adaptation.
The common misconception is 'linear biological thinking'—students assume that if high altitude requires more RBCs, adapted populations must have continuously massive RBC counts.
They fail to recognize the physiological trade-off where over-stressing the EPO 'rivet' crashes the cardiovascular system, necessitating a co-evolutionary down-regulation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Erythropoietin Function |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |