Which of the following best describes the state of chromosomes by the end of anaphase II of meiosis?

• A. Sister chromatids have separated and are moving toward opposite poles.
• B. Chromosomes are replicated and attached at their centromeres.
• C. Each chromosome consists of two identical sister chromatids.
• D. Homologous chromosomes are paired at the metaphase plate.

Answer: (A)

Verified step by step guidance

1. Understand the context of meiosis: Meiosis is a type of cell division that reduces the chromosome number by half, producing four haploid cells. It consists of two stages: meiosis I and meiosis II. Anaphase II occurs in meiosis II, where sister chromatids separate.
2. Recall the key events of anaphase II: During anaphase II, the sister chromatids of each chromosome are pulled apart by spindle fibers and move toward opposite poles of the cell. This is a critical step in ensuring that each daughter cell receives a single copy of each chromosome.
3. Eliminate incorrect options: Analyze the provided choices. For example, 'Chromosomes are replicated and attached at their centromeres' describes an earlier stage in the cell cycle, not anaphase II. Similarly, 'Each chromosome consists of two identical sister chromatids' refers to metaphase II, not anaphase II. 'Homologous chromosomes are paired at the metaphase plate' describes metaphase I, not anaphase II.
4. Focus on the correct description: By the end of anaphase II, the sister chromatids have separated and are moving toward opposite poles. This is the defining characteristic of this stage in meiosis II.
5. Conclude with the biological significance: The separation of sister chromatids ensures that each daughter cell receives the correct number of chromosomes, which is essential for maintaining genetic stability in gametes.