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Question #45488
The Question
A researcher observes a Citrus ovule where a chemical inhibitor has completely arrested the mitotic division of the generative cell within the pollen tube. Despite the absence of male gametes, the ovule matures into a seed containing multiple embryos. Which of the following provides the most accurate biological explanation for this phenomenon?
Options
- A.
The undivided generative cell fuses directly with the egg cell, forming a diploid zygote that subsequently cleaves into multiple embryos.
- B.
The vegetative cell undergoes endomitosis to become diploid and fertilizes the egg, bypassing the need for generative cell division.
- C.
Diploid nucellar cells surrounding the embryo sac divide and protrude into it, forming embryos independent of gametogenesis and syngamy.
- D.
The unfertilized haploid egg cell undergoes spontaneous diploidization and subsequent cleavage to form multiple clonal embryos.
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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
Generative_Cell|Polyembryony_Mechanisms|Embryo_Sac
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate 'seed formation' with 'obligate double fertilization'.
The trap lies in assuming that if the generative cell fails to divide, the plant must employ an alternative fertilization mechanism (like vegetative cell fusion or undivided generative cell fusion) to restore diploidy.
The correct logic requires recognizing that adventive polyembryony (nucellar embryony) is a purely maternal sporophytic budding process that renders the male gametophyte's generative output entirely irrelevant to the resulting embryos' ploidy.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Generative Cell Division |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |