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Question #45459
The Question
Erythropoietin (EPO), a peptide hormone secreted by the juxtaglomerular cells, regulates erythropoiesis by binding to specific receptors on bone marrow stem cells. In cases of chronic exogenous EPO doping (using synthetic variants with extended half-lives), the target cells eventually become desensitized to the hormone, leading to a plateau in red blood cell production. Based on the mechanism of hormone action, which of the following cellular mechanisms best explains this physiological desensitization?
Options
- A.
It occurs due to the down-regulation of intracellular receptors, preventing the hormone from directly altering gene expression.
- B.
It is a result of ligand-induced internalization and degradation of membrane-bound receptors, reducing target cell sensitivity.
- C.
It is caused by systemic negative feedback from the juxtaglomerular apparatus, which actively secretes enzymes to destroy bone marrow receptors.
- D.
It is caused by the exhaustion of secondary messengers, which fails to amplify the biochemical response despite continuous hormone-receptor binding.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Erythropoietin|Hormone_Receptors_Location|Hormone_Half_life_Logic
Why This Question Is Tricky
Common Mistakes
The Conceptual Pivot lies in correctly classifying EPO as a peptide hormone (requiring membrane-bound receptors) and applying the concept of 'Receptor Down-regulation' as the primary cellular mechanism for desensitization.
Students often confuse systemic negative feedback (which lowers hormone production) with cellular desensitization (which lowers receptor density), or they misattribute the mechanism to intracellular receptors, forgetting the biochemical nature of 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 |