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Question #45460
The Question
An individual inherits a genetic mutation causing a markedly reduced affinity of Erythropoietin (EPO) receptors on the erythroid progenitor cells in the bone marrow. Assuming the body's oxygen-sensing mechanisms remain intact, which of the following best describes the compensatory homeostatic response and the resulting physiological state?
Options
- A.
Juxtaglomerular (JG) cells will chronically hypersecrete EPO to overcome the receptor defect, resulting in elevated serum EPO and a near-normal to mildly reduced RBC count.
- B.
The macula densa cells will decrease EPO secretion due to a false state of 'apparent normoxia', leading to severe aplastic anemia.
- C.
The bone marrow will upregulate the production of EPO to stimulate the JG cells, resulting in secondary polycythemia.
- D.
Juxtaglomerular (JG) cells will chronically hypersecrete EPO, leading to a massive overproduction of RBCs (polycythemia) due to the loss of negative feedback.
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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
Erythropoietin|Incomplete_Dominance_Pheno-Geno|Feedback_Mechanism_Loops
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that a defective receptor automatically leads to a complete loss of function (e.g., severe anemia).
However, in endocrine negative feedback loops, receptor insensitivity (reduced affinity) leads to a compensatory hypersecretion of the hormone to maintain homeostasis (similar to insulin resistance).
Furthermore, the question tests the specific NCERT fact that JG cells (not macula densa or bone marrow) secrete EPO.
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 |