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Question #47439
The Question
In genetically modified Bt crops, the expressed Cry proteins are ingested by target insects as inactive protoxins. Following solubilization and proteolytic cleavage in the midgut, the active toxin binds to specific receptors on the epithelial cell membrane. What is the primary biophysical mechanism by which this binding leads to epithelial cell death?
Options
- A.
It induces the formation of non-selective pores, leading to the rapid dissipation of transmembrane electrochemical gradients and osmotic lysis.
- B.
It acts as an uncoupling agent in the inner mitochondrial membrane, halting ATP synthesis and causing metabolic starvation.
- C.
It competitively blocks voltage-gated sodium channels, preventing neural summation and causing flaccid paralysis of the gut.
- D.
It reverses the midgut pH from alkaline to highly acidic, denaturing structural proteins of the brush border epithelium.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Cry toxin|Membrane pores|Ion homeostasis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Bridging the NCERT fact of 'cell swelling and lysis' with its biophysical cause—the thermodynamic collapse of cellular polarity due to non-selective pore formation.
Students often memorize the end result without understanding that the immediate cause of death at the cellular level is the catastrophic dissipation of transmembrane electrochemical gradients.
Option C serves as a high-level trap by misapplying the concept of ion gradient failure to neural summation rather than epithelial osmotic balance.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Summation Kinetics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |