Crossing over occurs during the synapsis event of which stage of meiosis?

• A. Metaphase I
• B. Anaphase II
• C. Telophase I
• D. Prophase I

Answer: (D)

Verified step by step guidance

1. Understand that crossing over is the process where homologous chromosomes exchange genetic material, increasing genetic diversity.
2. Recall the stages of meiosis I: Prophase I, Metaphase I, Anaphase I, and Telophase I, and note that crossing over occurs early in meiosis I.
3. Identify that synapsis is the pairing of homologous chromosomes, which is a key event during Prophase I of meiosis.
4. Recognize that crossing over specifically happens during the synapsis event in Prophase I, when homologous chromosomes are tightly paired as tetrads.
5. Conclude that the correct stage for crossing over during synapsis is Prophase I, not Metaphase I, Anaphase II, or Telophase I.