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Question #46770
The Question
In a mutant eukaryotic cell line, a genetic defect compromises the ultrastructure of the nucleolus. The cells remain viable and perform basic metabolism but are completely non-motile due to the failure of ciliary assembly, specifically lacking axonemal dyneins. Based on the principles of cellular organelles, which of the following best explains this phenotypic correlation?
Options
- A.
The nucleolus is the primary site for the synthesis of tubulin monomers, which are directly transported to the basal body for 9+2 axoneme formation.
- B.
Compromised nucleolar function reduces active rRNA synthesis, thereby limiting the massive ribosomal translational capacity required to synthesize complex ciliary motor proteins.
- C.
The nucleolus stores the specific genetic blueprint for the 9+2 microtubular arrangement, and its degradation prevents the transcription of dynein mRNA.
- D.
The mutation disrupts the endomembrane system's ability to glycosylate axonemal proteins before they are targeted to the ciliary plasma membrane.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Nucleolar Functionality|Ciliary/Flagellar Ultrastructure|Endomembrane System Connectivity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating isolated NCERT facts (Nucleolus = rRNA synthesis; Cilia = proteinaceous 9+2 axoneme).
Students often fail to connect that massive structural assemblies like cilia require high ribosomal output.
Common Misconception: Confusing the nucleolus (rRNA synthesis) with the nucleoplasm (mRNA transcription), or assuming cytoskeletal proteins are processed through the Rough ER/Golgi endomembrane system.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Nucleolar Functionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |