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Question #45133
The Question
A transgenic Bt cotton field is infested by a mutant strain of the cotton bollworm. Analysis reveals that while the mutant larvae ingest the Cry1Ac protoxin, a shift in their gut microbiota has rendered their midgut pH abnormally acidic. What will be the immediate molecular consequence of this mutation, and how will it subsequently affect the population growth dynamics of the bollworm in this field?
Options
- A.
The protoxin crystals will fail to solubilize; the environmental resistance provided by the crop is nullified, allowing the r-selected pest population to exhibit exponential growth.
- B.
The solubilized protoxin will not be cleaved into its active form; the pest population will immediately stabilize at its carrying capacity (K) following a logistic growth model.
- C.
The active toxin will be denatured by the acidic pH before pore formation; the pest population will undergo a severe genetic bottleneck due to high mortality.
- D.
The protoxin will prematurely bind to foregut epithelial receptors; the population growth curve of the pest will shift from J-shaped to S-shaped.
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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
Carrying Capacity|Pest Population|Sigmoid Curve
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question bridges molecular biotechnology (the specific pH requirement for Cry toxin solubilization) with macro-ecological population models (exponential growth of r-selected pests when environmental resistance is removed).
Common Misconception: Students often confuse the sequence of Bt toxin activation (assuming cleavage fails before solubilization) and frequently misapply population models, assuming all populations default to logistic (S-shaped) growth, forgetting that insect pests exhibit classic exponential (J-shaped) outbreaks when unchecked.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology and Its Applications - Class 12 |
| Concept | Bt Toxin Activation Trigger |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |