During meiosis, crossing over can cause previously linked genes to become separated by moving to what?

• A. The same chromatid
• B. Different homologous chromosomes
• C. The nucleus
• D. The spindle

Answer: (B)

Crossing over in meiosis happens when non-sister chromatids of homologous chromosomes exchange pieces of DNA. This shuffles alleles and can break the original linkage of two genes that were on the same chromosome. Because segments are swapped between the two homologs, the genes can end up on the other homolog, effectively moving to different homologous chromosomes and creating recombinant chromosomes. The other options don’t describe this exchange mechanism: staying on the same chromatid would keep the genes linked, and the nucleus or the spindle are just cellular components involved in segregation, not the process by which linked genes are moved between chromosomes.