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Question #45492
The Question
If an angiosperm Megaspore Mother Cell (MMC) sustains severe DNA damage prior to division, conserved eukaryotic cell cycle checkpoints will arrest its meiotic progression, preventing the development of the embryo sac. Which of the following statements accurately contrasts this DNA-damage-induced arrest in plants with the physiological meiotic arrests observed in normal human oogenesis?
Options
- A.
The damaged MMC arrests to prevent the formation of a linear tetrad, whereas a normal human primary oocyte naturally arrests at the Diplotene stage of Prophase I independent of DNA damage.
- B.
The damaged MMC arrests at Metaphase II to allow DNA repair, which is exactly homologous to the natural arrest of a human secondary oocyte prior to fertilization.
- C.
The meiotic arrest in the MMC prevents the three successive mitotic divisions of the functional megaspore, whereas human oogenesis lacks any physiological meiotic arrest phases.
- D.
The damaged MMC undergoes unequal meiotic divisions to extrude polar bodies, whereas the human primary oocyte naturally arrests at the Pachytene stage.
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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
Megaspore Mother Cell|Meiotic Arrest Points|Chiasmata
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between a 'pathological' cell cycle arrest (due to DNA damage checkpoints, applicable to both plants and animals) and a 'physiological' developmental arrest (unique to animal oogenesis, e.g., Diplotene arrest in primary oocytes).
Students often confuse the reasons for meiotic arrest across different kingdoms and misidentify the specific sub-stages of Prophase I where these arrests occur.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Megasporogenesis Symmetry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |