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Question #46480
The Question
Continuous cultivation of Bt cotton expressing the cryIAc gene imposes extreme selection pressure on cotton bollworms, often leading to the rapid fixation of resistance alleles and a systemic breakdown of Integrated Pest Management (IPM). If a biocontrol agent from the genus Nucleopolyhedrovirus (NPV) is subsequently deployed to manage these resistant pests, which of the following statements is INCORRECT regarding the biological and evolutionary principles of this scenario?
Options
- A.
The rapid resistance to the cryIAc toxin is most commonly due to mutations altering the specific receptors on the surface of the pest's midgut epithelial cells.
- B.
NPV is an ideal candidate for this IPM recovery strategy because it provides narrow-spectrum insecticidal action without negatively impacting non-target beneficial insects.
- C.
To delay the initial cryIAc resistance, a 'refuge strategy' of planting non-Bt cotton is used to ensure the rapid fixation of homozygous recessive resistance alleles in the pest population.
- D.
The cryIAc protoxin requires an alkaline pH in the insect gut to be solubilized into an active form, a physiological prerequisite that is independent of the NPV's mode of action.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Co-evolutionary Resistance|Baculovirus Host Specificity|Cry Gene Specificity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the 'refuge strategy' as a tool for managing Bt resistance but fail to grasp the underlying population genetics.
The trap relies on confusing the evolutionary goal (maintaining susceptible alleles to dilute resistance) with the evolutionary failure (the rapid fixation of homozygous recessive resistance alleles).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Co-evolutionary Resistance |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |