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Question #47507
The Question
A diploid meiocyte of a fern (2n = 24, initial G1 DNA content = 20 pg) undergoes sporic meiosis to transition into the haplontic phase. During the S-phase, compromised DNA polymerase fidelity introduces several base mismatches. If the cell successfully forms stable dyads at the end of Telophase I, what is the chromosome number and DNA content of each dyad cell, and which checkpoint was primarily responsible for halting the cycle to allow mismatch repair prior to reductional division?
Options
- A.
12 chromosomes, 10 pg DNA; G1/S checkpoint
- B.
12 chromosomes, 20 pg DNA; G2/M checkpoint
- C.
24 chromosomes, 20 pg DNA; G2/M checkpoint
- D.
12 chromosomes, 20 pg DNA; Spindle assembly checkpoint
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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
Protobionts|RNA World|Gametic Fusion|Zygotic Meiosis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently conflate the halving of chromosome number with the absolute halving of DNA to the 1C state, forgetting that after Meiosis I, chromosomes still consist of two sister chromatids (n, 2C).
Furthermore, the trap tests the functional distinction between checkpoints: the G1/S checkpoint commits the cell to divide, the G2/M checkpoint ensures DNA replication is complete and error-free, and the M checkpoint ensures proper spindle attachment.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Haplontic-Diplontic Life Cycle Transitions |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |