Which of the following events occurs during prophase I of meiosis?

• A. Sister chromatids separate and move to opposite poles.
• B. The nuclear envelope reforms around separated chromosomes.
• C. Homologous chromosomes undergo synapsis and crossing over occurs.
• D. Chromosomes align individually at the metaphase plate.

Answer: (C)

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, creating four haploid cells. It consists of two stages: meiosis I and meiosis II. Prophase I is a key phase in meiosis I.
2. Recognize the key events of prophase I: During prophase I, homologous chromosomes pair up in a process called synapsis. This pairing allows for crossing over, where segments of genetic material are exchanged between homologous chromosomes, increasing genetic diversity.
3. Eliminate incorrect options: Sister chromatids separating and moving to opposite poles occurs during anaphase II, not prophase I. The nuclear envelope reforms around separated chromosomes during telophase, not prophase I. Chromosomes aligning individually at the metaphase plate occurs during metaphase II, not prophase I.
4. Focus on the correct event: Homologous chromosomes undergoing synapsis and crossing over is specific to prophase I of meiosis. This process is crucial for genetic recombination and diversity.
5. Summarize the importance: Synapsis and crossing over during prophase I ensure that homologous chromosomes exchange genetic material, which contributes to genetic variation in gametes produced by meiosis.