객관식
In meiosis, what is the direct outcome of completion of meiosis II for a single cell that entered meiosis I (assuming typical animal meiosis and no nondisjunction)?
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9. Mitosis and Meiosis
Meiosis
객관식
During interphase preceding meiosis I, which key event must occur to ensure that each chromosome consists of two sister chromatids?
A
DNA replication occurs during S phase, producing sister chromatids for each chromosome.
B
Homologous chromosomes separate into different cells, reducing the chromosome number by half.
C
Crossing over occurs between homologous chromosomes, creating chiasmata.
D
Sister chromatids separate at the centromere and move to opposite poles.
검증된 단계별 안내1
Understand the context: The question asks about the key event during interphase before meiosis I that ensures each chromosome consists of two sister chromatids.
Recall the phases of the cell cycle: Interphase includes G1, S, and G2 phases. The S phase is when DNA replication occurs.
Identify the role of DNA replication: During the S phase, each chromosome is duplicated, resulting in two identical sister chromatids connected at the centromere.
Recognize that sister chromatids are necessary for meiosis I: Having two sister chromatids per chromosome allows for proper segregation during meiosis I and II.
Conclude that the key event is DNA replication during the S phase, which produces sister chromatids for each chromosome before meiosis I begins.
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