Bacillus thuringiensis CryA controls certain caterpillar pests by
Show Hint
- turning toxic in the acidic pH of their gut medium
- turning toxic in the alkaline medium of their gut
- repelling them from the crops
- inducing satiation in them
The Correct Option is B
Solution and Explanation
Step 1: Understanding Bt CryA protein.
Bacillus thuringiensis (Bt) produces Cry proteins, which are used in genetically modified crops to provide pest resistance.
Step 2: Activation of CryA protein.
When caterpillar pests ingest CryA protein, it reaches their gut, where the alkaline pH environment activates the CryA protein. This activated toxin binds to the gut epithelial cells of the insect, leading to cell lysis and ultimately killing the pest.
Step 3: Eliminate other options.
Option (1): CryA is not activated in acidic pH.
Option (3): CryA doesn't repel insects; it kills them.
Option (4): It does not induce satiation.
Thus, the correct answer is that CryA becomes toxic in the alkaline medium of the caterpillar gut.
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