Before You Begin
Question #45429
The Question
The insecticidal mechanism of Bacillus thuringiensis (Bt) toxin involves a highly specific sequence of biochemical events in the target insect. Which of the following statements regarding the activation and physiological action of the Cry protein is INCORRECT?
Options
- A.
Solubilization of the inactive protoxin crystals is strictly dependent on the alkaline pH of the insect's midgut.
- B.
The activated toxin binds to specific receptors on the surface of midgut epithelial cells and inserts into the membrane to form pores.
- C.
The primary cause of epithelial cell death is the uncontrolled flux of ions and water through these pores, leading to cellular swelling and osmotic lysis.
- D.
The active toxin acts as a neurotoxin by blocking voltage-gated calcium channels at the neuromuscular junction, preventing synaptic transmission.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Calcium_Ion_Influx|Neurotransmitters|Bt_Toxin|Midgut_pH
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Functional Confusion.
Students often assume all insecticidal toxins cause death via neurotoxicity (disrupting synaptic transmission or calcium homeostasis at the neuromuscular junction).
The trap relies on distinguishing the specific localized necrotic mechanism of Bt toxin (osmotic lysis of midgut epithelia) from general neurotoxic pesticides.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Calcium Homeostasis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |