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Question #45491
The Question
An angiospermic plant is experimentally treated with colchicine precisely during the meiotic division of the Megaspore Mother Cell (MMC). Assuming the resulting functional megaspore survives and successfully develops into a mature Polygonum-type embryo sac, which of the following statements correctly describes the ploidy of the egg cell and the most likely subsequent reproductive consequence?
Options
- A.
The egg cell will be haploid (n), but the plant will exhibit parthenocarpy due to spindle fiber inhibition.
- B.
The egg cell will be diploid (2n), potentially leading to the development of an embryo without fertilization (apomixis).
- C.
The egg cell will be tetraploid (4n), resulting in a sterile embryo sac due to the failure of cytokinesis.
- D.
The egg cell will be diploid (2n), leading to adventive embryony directly from the surrounding nucellar tissue.
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
Megaspore Mother Cell (MMC)|Megaspore Tetrad|Polyploidy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students must synthesize the cellular effect of colchicine (spindle inhibition) with the meiotic process of the MMC.
A common misconception is assuming colchicine always creates tetraploids; while it doubles ploidy in somatic mitosis (2n to 4n), in meiosis, it prevents the reduction from 2n to n, resulting in 2n spores.
Furthermore, students must distinguish between different types of apomixis (diplospory via unreduced MMC vs. adventive embryony via nucellus).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Megasporogenesis Symmetry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |