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Question #45907
The Question
Both the lac operon in E. coli and the cry gene product (Bt toxin) in transgenic plants act as 'conditional switches' that require specific environmental triggers for their functional manifestation. Which of the following statements correctly distinguishes the molecular nature of these two biological switches?
Options
- A.
The lac operon is regulated at the translational level by allolactose, while the cry gene is regulated at the transcriptional level by the alkaline pH of the insect gut.
- B.
The lac operon utilizes a ligand-induced conformational change for transcriptional de-repression, whereas Bt toxin undergoes environment-induced solubilization by alkaline pH for post-translational activation.
- C.
Both mechanisms represent positive regulation, where allolactose and alkaline pH act as direct inducers that bind to their respective promoter regions.
- D.
The lac operon is continuously transcribed but requires allolactose for activation, whereas the Bt protoxin requires an acidic pH for conversion into an active toxin.
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
Lac Operon|Bt Toxin|Alkaline_pH|Inducer
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the levels of the Central Dogma where biological control is exerted.
Students often memorize 'inducer' and 'activation' without categorizing whether the switch occurs at the transcriptional level (lac operon via ligand binding) or the post-translational level (Bt toxin via environmental pH).
A secondary trap is the classic 'acidic vs. alkaline' pH confusion for Bt toxin activation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Lac Operon Inducibility |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |