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Question #45129
The Question
A novel transgenic cotton plant is engineered to express the cry1Ac gene. However, due to an unintended pleiotropic effect, the plant's leaf tissues also accumulate high concentrations of a strong organic acid. When cotton bollworm larvae feed on these leaves, they survive and cause extensive crop damage. Based on the biochemical requirements of Bt toxin activation, what is the most scientifically accurate explanation for the failure of the pest-resistance trait?
Options
- A.
The acidic pH prematurely activates the protoxin within the plant tissue, leading to its enzymatic degradation before ingestion by the larvae.
- B.
The acidic plant biomass neutralizes the alkaline pH of the larval midgut, preventing the solubilization of the crystalline protoxin.
- C.
The organic acid competitively inhibits the larval midgut proteases, preventing the cleavage of the already solubilized protoxin.
- D.
The acidic environment denatures the midgut epithelial receptors, preventing the active toxin from inducing cell swelling and lysis.
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|Midgut Epithelium|Cry Proteins
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'Bt toxin kills insects' without internalizing the absolute prerequisite condition for its activation (alkaline pH for solubilization).
The trap exploits the human-centric bias where students associate acidic environments with protein digestion (like pepsin in the human stomach), whereas the insect midgut requires an alkaline environment to solubilize the specific Cry protein crystals.
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 |