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Question #45477
The Question
A researcher treats the anther of a diploid angiosperm (2n = 24) with colchicine specifically during the meiotic division of its Microspore Mother Cells (MMCs). The resulting pollen grains are then used to pollinate the stigma of an untreated, normal female plant of the same species. Assuming successful double fertilization, what will be the exact chromosome number in the vegetative cell of the pollen, the resulting zygote, and the Primary Endosperm Nucleus (PEN), respectively?
Options
- A.
Vegetative cell: 24, Zygote: 36, PEN: 48
- B.
Vegetative cell: 12, Zygote: 24, PEN: 36
- C.
Vegetative cell: 48, Zygote: 60, PEN: 84
- D.
Vegetative cell: 24, Zygote: 48, PEN: 72
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
Microspore Mother Cell|Tapetum|Meiotic_Spindle_Disruption
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often mechanically memorize 'Zygote is 2n, Endosperm is 3n' without tracing the exact ploidy contribution of altered gametes.
The trap tests the ability to apply the mechanism of colchicine (spindle inhibition causing non-disjunction/polyploidy) exclusively to the male gametophyte generation, while keeping the female gametophyte's ploidy normal, and then mathematically executing double fertilization.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Microsporogenesis Ploidy Shift |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |