During meiosis II, sister chromatids are separated. What process might cause sister chromatids to differ from each other?

• A. Mutation during DNA replication
• B. Independent assortment during metaphase II
• C. Random fertilization
• D. Crossing over during prophase I

Answer: (D)

Verified step by step guidance

1. Understand that meiosis is a type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell.
2. Recall that meiosis consists of two stages: meiosis I and meiosis II. During meiosis I, homologous chromosomes are separated, while meiosis II involves the separation of sister chromatids.
3. Recognize that crossing over is a process that occurs during prophase I of meiosis I, where homologous chromosomes exchange genetic material. This results in genetic recombination, which increases genetic diversity.
4. Identify that crossing over can cause sister chromatids to differ from each other because the exchange of genetic material between homologous chromosomes can lead to new combinations of alleles on each chromatid.
5. Conclude that while mutation during DNA replication, independent assortment, and random fertilization contribute to genetic variation, it is the crossing over during prophase I that directly causes sister chromatids to differ from each other in meiosis II.