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Question #46595
The Question
A novel insect pest is found to be completely resistant to Bt cotton despite ingesting adequate amounts of the transgenic plant tissue. Physiological analysis of the pest reveals that its midgut maintains a highly acidic environment (pH 4.5), although it possesses the exact same gut proteases found in susceptible pests. Based on the principles of Bt toxin activation, which of the following is the primary reason for this resistance?
Options
- A.
The acidic pH denatures the active Cry protein, preventing it from binding to the midgut epithelial receptors.
- B.
The crystalline inclusion bodies fail to solubilize, rendering the protoxin inaccessible to the gut proteases for cleavage.
- C.
The acidic environment inhibits the transcription of the cry gene within the ingested plant cells.
- D.
The protoxin is successfully cleaved by the proteases, but the acidic pH prevents the formation of pores in the midgut epithelium.
Check Your Answer
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
Bacillus_thuringiensis|Cry_Protein|Midgut_pH|Proteolytic_Activation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'alkaline pH activates the toxin' without understanding the sequential mechanism of activation (Alkaline pH -> Solubilization -> Proteolytic cleavage).
The trap lies in presenting a scenario where the necessary proteases are present, tempting students to believe cleavage (Option D) can occur independently of the pH-dependent solubilization step.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Microbes in Human Welfare - Class 12 |
| Concept | Biocontrol Agents Synergy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |