During Meiosis I, what happens to homologous chromosomes?

• A. Sister chromatids separate to opposite poles
• B. DNA replication occurs
• C. Two nuclei form
• D. Homologous chromosomes separate to different poles

Answer: (D)

In meiosis I, the key event is the separation of homologous chromosomes. These chromosome pairs, each containing one chromosome from mom and one from dad, line up and trade segments during pairing, then are pulled to opposite poles in anaphase I. This is what halves the chromosome number in the resulting cells. The sister chromatids stay together through meiosis I and are only pulled apart later during meiosis II. DNA replication, meanwhile, happens earlier—in the S phase before meiosis starts—not during meiosis I. So the statement that best fits what happens to homologous chromosomes during this stage is that homologous chromosomes separate to different poles.