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Question #45182
The Question
A transgenic Bt cotton crop expressing the cry1Ac gene effectively controls native bollworms. However, an invasive lepidopteran species displaces the native population and devastates the crop. Histological studies of the invasive pest show that the ingested Bt crystals remain completely intact within its alimentary canal. Which of the following is the most likely physiological reason for the failure of the Cry protein against this invasive species?
Options
- A.
The invasive species lacks the specific alkaline pH in its midgut required to solubilize the protoxin crystals.
- B.
The invasive species lacks the specific acidic pH in its midgut required to convert the protoxin into an active toxin.
- C.
The invasive species possesses mutated midgut epithelial receptors that prevent the binding of the active Cry toxin.
- D.
The invasive species secretes specific gut proteases that rapidly degrade the active toxin before it can create pores.
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
RNAi Vector Source|Nutrient Cycling Reservoirs|Decomposition Rate Modifiers
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the sequential steps of Bt toxin action (Ingestion -> Solubilization via alkaline pH -> Activation -> Binding to midgut receptors -> Cell lysis).
The trap lies in Options C and D, which represent valid theoretical resistance mechanisms, but contradict the specific histological evidence provided ('crystals remain intact').
This forces the student to pinpoint the exact biochemical failure at the solubilization phase, testing deep NCERT comprehension rather than superficial memorization.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology and Its Applications - Class 12 |
| Concept | RNAi Vector Source |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |