Crossing-over during meiosis can do what to genes that were on the same chromosome?

• A. They remain attached and never separate
• B. They sometimes separate onto homologous chromosomes
• C. They duplicate into two identical copies
• D. They move to different chromosomes

Answer: (B)

Crossing-over during meiosis shuffles genetic material between homologous chromosomes by exchanging corresponding segments between non-sister chromatids. This exchange can break the usual linkage of genes that sit on the same chromosome, so those genes can end up on the two different homologous chromosomes that go into gametes. In other words, alleles that were once together on one chromosome can be separated onto separate chromosomes as a result of recombination, creating new allele combinations in gametes. This process increases genetic variation.