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Question #45229
The Question
A highly lipid-soluble anesthetic is applied to an isolated mammalian retina. The anesthetic intercalates into the phospholipid bilayer of the rod cells, disrupting the fluid-mosaic packing and preventing the normal conformational changes of the embedded opsin proteins upon light exposure. Based on the mechanism of visual phototransduction, which of the following best describes the resulting physiological state of the rod cells when exposed to light?
Options
- A.
The intracellular cGMP levels will rapidly fall, causing continuous closure of Na+ channels and permanent hyperpolarization.
- B.
The rod cells will fail to undergo hyperpolarization, maintaining the influx of Na+ ions and the continuous release of neurotransmitters.
- C.
The structural change in opsin will be accelerated, leading to the immediate generation of action potentials in the photoreceptor cells.
- D.
The bipolar cells will become continuously depolarized due to the sudden absence of inhibitory signals from the rod cells.
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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
Lipid Amphipathic Nature|Retina Phototransduction Cascade|Neural Control
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The counter-intuitive nature of photoreceptor physiology.
Students often assume that a sensory stimulus (light) causes depolarization and action potentials in the receptor cell.
However, rod cells are uniquely depolarized in the dark (dark current) and hyperpolarize in response to light.
The trap tests whether the student understands that blocking the receptor's function freezes the cell in its 'dark' (depolarized) state, thereby preventing the signal transmission to bipolar cells.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Lipid Amphipathic Nature |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |