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Question #45132
The Question
A biotechnologist develops a transgenic cotton plant expressing the cry1Ac gene to confer resistance against cotton bollworms. To confirm the expression of the gene, an ELISA test is performed on the leaf extract, which yields a strong positive result. However, when bollworms feed on these transgenic leaves, they do not die. Which of the following is the most scientifically accurate explanation for this observation?
Options
- A.
ELISA detects specific epitopes of the Cry protein but cannot differentiate between the inactive protoxin and a structurally modified form that resists proteolytic cleavage in the alkaline midgut.
- B.
The plant successfully synthesized the active toxin as detected by ELISA, but the acidic pH of the bollworm's midgut denatured the protein before it could create pores in the epithelium.
- C.
ELISA detects the mRNA transcript of the cry1Ac gene, confirming transcription, but post-transcriptional modifications prevented the translation of the active protoxin.
- D.
The Cry protein was expressed as an inactive protoxin, but the ELISA test utilizes an alkaline buffer that artificially activated the toxin during the assay, yielding a false positive for functionality.
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
Cry Proteins|ELISA Logic|Antigen-Antibody Specificity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between molecular detection (ELISA detecting epitopes) and biological functionality (alkaline pH-dependent proteolytic cleavage of protoxin).
Students often confuse a positive molecular test with guaranteed biological efficacy.
The distractors test common NCERT misconceptions: confusing the pH of the insect gut (alkaline vs. acidic) and confusing the target molecule of ELISA (protein vs. mRNA).
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 |