Question

which statements describe crossing over?
occurs between duplicated sister chromatids
increases genetic variation across gametes
separates chromosome pairs into gametes
occurs between homologous chromosomes

Explanation:

• Crossing over occurs between homologous chromosomes (not sister chromatids). During meiosis, homologous chromosomes pair up. Portions of their chromatids can swap, which is crossing - over.
• This exchange of genetic material between homologous chromosomes increases genetic variation across gametes. Each gamete gets a unique combination of genetic material due to crossing - over.
• Separating chromosome pairs into gametes is the process of chromosome segregation (e.g., in anaphase of meiosis), not crossing - over.

Answer:

• B. increases genetic variation across gametes
• D. occurs between homologous chromosomes