What is the exchange of genetic material between homologous chromosomes during meiosis I called?

• A. Crossing over
• B. Independent assortment
• C. Telophase
• D. Cytokinesis

Answer: (A)

During meiosis I, the exchange of genetic material between homologous chromosomes is called crossing over. This happens in prophase I when homologous chromosomes pair up and form physical connections, allowing chromatids to swap segments at points called chiasmata. The outcome is recombinant chromosomes that carry mixed alleles from both parental origins, which boosts genetic diversity in the resulting gametes.

Crossing over is distinct from independent assortment, which describes how different chromosome pairs align and separate independently to mix maternal and paternal chromosomes without exchanging segments. Telophase is the stage when chromosomes arrive at the poles and new nuclei form, and cytokinesis is the division of the cytoplasm after mitosis or meiosis.