Question:
Assertion A: Bt toxin does not kill Bacillus thuringiensis.
Reason R: The Bt toxin gets activated due to the alkaline pH of the insect gut.
Assertion A: Bt toxin does not kill Bacillus thuringiensis.
Reason R: The Bt toxin gets activated due to the alkaline pH of the insect gut.
Reason R: The Bt toxin gets activated due to the alkaline pH of the insect gut.
Show Hint
The toxin is a "sleeper agent" that only wakes up in the insect's alkaline stomach.
Updated On: May 14, 2026
- Both A and R are correct and R is the correct explanation of A
- Both A and R are correct but R is not the correct explanation of A
- A is correct but R is not correct
- A is not correct but R is correct
Show Solution
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The Correct Option is A
Solution and Explanation
Step 1: Concept
Bacillus thuringiensis (Bt) produces insecticidal proteins that exist as inactive protoxins.
Step 2: Meaning
The bacterium itself is safe because the toxin is not in its active form inside the cell.
Step 3: Analysis
When an insect ingests the Bt crystals, the highly alkaline environment of its midgut solubilizes the crystals and converts the protoxin into its active, lethal form.
Step 4: Conclusion
Assertion A is true, and Reason R explains the mechanism of activation that makes it selective to insects. Final Answer: (A)
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