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Question #46968
The Question
In Euglena, the proteinaceous pellicle provides structural plasticity (metaboly), allowing dynamic morphological responses to the environment. If a mutation renders this pellicle rigid, the organism loses its adaptive flexibility. Analogously, in human physiology, which of the following conditions best represents a similar loss of 'functional plasticity,' where a hormonal feedback loop becomes rigidly 'locked' in an active state, causing the hyper-fixation of metabolic end-products despite intact physiological sensors?
Options
- A.
Exophthalmic goitre, where autoantibodies continuously stimulate the thyroid gland, bypassing the negative feedback inhibition of thyroxine.
- B.
Diabetes mellitus type I, where the autoimmune destruction of beta cells completely halts the production of insulin.
- C.
Simple goitre, where dietary iodine deficiency prevents thyroxine synthesis, leading to continuous TSH secretion.
- D.
Tetany, where diminished parathyroid hormone secretion leads to a rigid, locked state of sustained skeletal muscle contraction.
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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
Euglenoid Pellicle Flexibility|Skeletal Muscle Striation Pattern|Intercalated Disc Function
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the physical manifestation of a disease (like muscle rigidity in tetany) with the underlying regulatory mechanism (a locked feedback loop).
The analogy requires mapping structural plasticity (pellicle) to regulatory plasticity (negative feedback).
Exophthalmic goitre perfectly illustrates a system where the 'off switch' is bypassed by an exogenous-like factor (autoantibody), locking the system in a hyper-metabolic state despite the body's attempt to down-regulate it.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biological Classification - Class 11 |
| Concept | Euglenoid Pellicle Flexibility |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |