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Question #45773
The Question
The eukaryotic flagellum emerges from a basal body, presenting a critical structural transition from a 9+0 to a 9+2 microtubular arrangement. Which of the following statements regarding the ultrastructure and origin of this complex is INCORRECT?
Options
- A.
The basal body acts as the Microtubule Organizing Center (MTOC) for the axoneme and represents an autogenous structure, unlike endosymbiotically derived organelles.
- B.
The central proteinaceous hub of the basal body extends continuously into the axoneme to form the central pair of singlet microtubules.
- C.
In the axoneme, the central sheath is connected to one tubule of each peripheral doublet by radial spokes, resulting in exactly nine spokes.
- D.
Despite lacking an independent genome, the basal body-centriole complex self-duplicates in the cytoplasm during the S-phase of the cell cycle.
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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
Centriole|Basal_Body|Ancestral_Protist
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the central 'hub' of the centriole (9+0) with the 'central pair' of microtubules in the axoneme (9+2), mistakenly assuming the central structure is continuous.
The question also tests the evolutionary distinction between autogenous cytoskeletal elements (centrioles) and exogenous endosymbionts (mitochondria) regarding DNA and replication.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Ciliary/Flagellar Ultrastructure |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |