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Question #45585
The Question
In a mutant angiosperm, the Megaspore Mother Cell (MMC) suffers a complete failure of meiosis but directly undergoes the standard three rounds of free nuclear mitosis to form a Polygonum-type embryo sac. If this flower is pollinated by pollen from a normal wild-type plant of the same species, what will be the ploidy level of the resulting zygote and Primary Endosperm Nucleus (PEN), respectively?
Options
- A.
3n and 5n
- B.
2n and 3n
- C.
3n and 4n
- D.
4n and 6n
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
Mendelian Gamete Frequency|Megasporogenesis Symmetry|Embryo Sac Nuclei Count
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often rote-learn the ploidy of the embryo sac cells.
This question forces them to apply the stoichiometry of double fertilization (n + egg vs. n + polar nucleus 1 + polar nucleus 2) to an unreduced (2n) embryo sac.
The primary trap is forgetting that the central cell contains TWO polar nuclei, meaning an unreduced central cell is 4n prior to fertilization, not 2n.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Mendelian Gamete Frequency |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |