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Question #45952
The Question
To induce a differentiated plant mesophyll cell to revert to a totipotent meristematic state (dedifferentiation), its genome must undergo widespread 'de-repression'. While conceptually analogous to the induction of the lac operon in E. coli, the eukaryotic mechanism fundamentally differs because:
Options
- A.
Eukaryotic de-repression relies on chromatin remodeling, such as histone acetylation, to expose promoters, whereas the lac operon is de-repressed by an inducer binding to a repressor protein to unblock the operator.
- B.
Eukaryotic totipotency requires the simultaneous de-repression of polycistronic structural genes, whereas the lac operon regulates a monocistronic transcriptional unit.
- C.
Eukaryotic de-repression involves the removal of introns by spliceosomes to physically unblock the promoter, a regulatory step absent in the lac operon.
- D.
Eukaryotic structural genes are de-repressed by the activation of RNA polymerase I, whereas the lac operon relies on a single DNA-dependent RNA polymerase.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Meristematic Totipotency|Transcriptional Unit Boundaries|Lac Operon Inducibility
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the lac operon as the universal model for gene regulation without distinguishing the physical boundaries of eukaryotic DNA packaging (nucleosomes/chromatin).
The trap in Option B reverses the monocistronic/polycistronic NCERT fact.
The trap in Option D tests the specific function of eukaryotic RNA polymerases (Pol I transcribes rRNA, Pol II transcribes mRNA).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Meristematic Totipotency |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |