In the first meiotic interphase, how many times does DNA replication occur?

• A. Twice
• B. Three times
• C. Not at all
• D. Once

Answer: (D)

DNA replication happens once before meiosis I begins, during the S phase of the first interphase. This single replication duplicates the genome so each chromosome becomes a pair of sister chromatids held together at the centromere. After replication, homologous chromosomes pair up and may exchange genetic material during prophase I, then the cells proceed through meiosis I where homologs separate while the sister chromatids stay together. There’s no additional DNA replication between meiosis I and meiosis II, so the final gametes receive just one chromatid from each chromosome.