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Question #47520
The Question
In heterosporous pteridophytes like Selaginella, the retention of the female gametophyte on the parent sporophyte is considered a precursor to the seed habit. If a non-disjunction event causes aneuploidy (2n-1) in the Megaspore Mother Cell (MMC), which of the following represents the primary physiological reason this variant fails to sustain embryogenesis?
Options
- A.
The reduced megagametophyte suffers metabolic failure due to an unbalanced genome, rendering it unable to utilize maternal reserves to nourish the zygote.
- B.
The aneuploid megaspore defaults to forming an independent, monoecious prothallus, disrupting the evolutionary advantage of heterospory.
- C.
The lack of a complete chromosome set prevents the formation of a pollen tube, permanently halting siphonogamous fertilization.
- D.
The MMC fails to undergo synchronous mitotic divisions, preventing the formation of the archegonium within the megasporangium.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Pteridophyte Heterospory Evolution|Kranz Anatomy Adaptations|Chlorophyll-a vs Accessory Pigments
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'heterospory is the precursor to the seed habit' but fail to connect it to the physiological dependence of the female gametophyte on the sporophyte.
The trap tests the ability to link cytogenetics (aneuploidy causing metabolic failure in a dependent structure) with pteridophyte life cycles, while actively avoiding distractors that mix up meiotic/mitotic events (Option D) or misattribute advanced gymnosperm/angiosperm features like pollen tubes to pteridophytes (Option C).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Pteridophyte Heterospory Evolution |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |