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Question #47440
The Question
A genetic mutation in a patient causes the cGMP-gated sodium channels in the outer segment of rod cells to remain permanently open, regardless of photon exposure. Which of the following will be the physiological consequence of this mutation when the patient is exposed to bright light?
Options
- A.
The rod cells will hyperpolarize, decreasing neurotransmitter release and signaling the presence of light to bipolar cells.
- B.
The rod cells will remain depolarized, continuously releasing neurotransmitters and mimicking the physiological state of constant darkness.
- C.
The rod cells will generate continuous action potentials due to the massive sodium influx, leading to photophobia.
- D.
The dissociation of retinal from opsin will be completely inhibited, preventing any structural change in the photoreceptor.
Check Your Answer
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
Rhodopsin|cGMP-phosphodiesterase|Na+ Channels|Hyperpolarization
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that all sensory receptors depolarize upon stimulation.
Photoreceptors are a unique exception; they hyperpolarize in response to light and are depolarized at rest (dark current).
Furthermore, students frequently fall for the trap in Option C, forgetting that rods and cones do not generate action potentials (only ganglion cells do), but rather graded potentials.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Retina Phototransduction Cascade |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |