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Question #46761
The Question
During the development of a typical Polygonum-type embryo sac, the functional megaspore undergoes strictly free-nuclear mitotic divisions. If an experimental agent prematurely stabilizes the spindle midzone microtubules (halting dynamic instability) during the first mitotic division, which of the following represents the most accurate physiological consequence?
Options
- A.
The megaspore will undergo immediate premature cytokinesis, forming a 2-celled structure due to early cell plate formation.
- B.
The metaphase-anaphase transition will be blocked, arresting development at the syncytial stage and preventing eventual phragmoplast-mediated cellularization.
- C.
The nuclear envelope will fail to disassemble, preventing CDK/Cyclin phosphorylation and arresting the cell in the G2 phase.
- D.
The free-nuclear divisions will continue normally, but the final organization of the egg apparatus and antipodals will be inverted.
Check Your Answer
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
Microtubule Dynamic Instability|Cell Cycle and Cell Division|Embryo Sac Nuclei Count
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'free-nuclear division lacks cytokinesis' but fail to connect that karyokinesis itself still strictly relies on the dynamic instability of the spindle apparatus.
The trap (Option A) plays on the misconception that the mere presence of a stabilized spindle midzone automatically initiates immediate cell plate formation, ignoring that the metaphase-anaphase transition must occur first and that cellularization in the embryo sac is strictly delayed until the 8-nucleate stage.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Microtubule Dynamic Instability |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |