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Question #46993
The Question
In an Ascomycete fungus, the dikaryotic ascogenous hyphae (n+n) undergo karyogamy to form a diploid zygote (2n = 10). During the subsequent meiosis, a failure in the spindle assembly checkpoint results in the non-disjunction of a single bivalent exclusively during Anaphase I. Assuming Meiosis II proceeds normally, which of the following correctly describes the chromosomal constitution and chromatid state of the four resulting nuclei prior to the post-meiotic mitosis?
Options
- A.
Two nuclei will contain 6 chromosomes and two will contain 4 chromosomes; all chromosomes will consist of a single chromatid.
- B.
Two nuclei will contain 6 chromosomes and two will contain 4 chromosomes; all chromosomes will consist of two sister chromatids.
- C.
Two nuclei will contain 5 chromosomes, one will contain 6, and one will contain 4; all chromosomes will consist of a single chromatid.
- D.
Four nuclei will contain 5 chromosomes each, but two nuclei will possess an aberrant DNA content due to malsegregation.
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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
Phycomycetes_Aseptate_Hyphae|Niche_Overlap_vs_Resource_Partitioning|Primary_Succession_Facilitation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Differentiating the exact ploidy and chromatid outcomes of Meiosis I versus Meiosis II non-disjunction.
A common misconception is confusing the 100% aneuploidy rate of Anaphase I errors (two n+1, two n-1) with the 50% aneuploidy rate of Anaphase II errors (two n, one n+1, one n-1), while also failing to track the transition from dyad (two chromatids) to monad (single chromatid) states.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biological Classification - Class 11 |
| Concept | Phycomycetes Aseptate Hyphae |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |