Biology Biotechnology PMDC Conceptual Practice
PMDC Verified Question 24 of 65
The insecticidal protein crystal of Bacillus thuringiensis is encoded by gene:
A
cry
B
lacZ
C
amp
D
tet
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: cry
Concept:

Transgenic insect resistance mechanisms via Bt endotoxins.

Solution:

The crystalline insecticidal endotoxin proteins (Crystal proteins) produced by Bacillus thuringiensis are encoded by cry genes (e.g., cry1Ac, cry2Ab).

Why other options are incorrect:

  • lacZ: Encodes \( \beta \)-galactosidase enzyme used in blue-white screening.


  • amp: Encodes \( \beta \)-lactamase conferring ampicillin resistance in selection plasmids.


  • tet: Encodes efflux pump proteins conferring tetracycline resistance.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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