Question

How does the process of crossing over during meiosis lead to an increase in genetic diversity?
Responses

Sister chromatids separate from each other and exchange DNA fragments with nearby chromosomes.
Sister chromatids separate from each other and exchange DNA fragments with nearby chromosomes.

Homologous chromosomes exchange DNA segments, resulting in different combinations of alleles.
Homologous chromosomes exchange DNA segments, resulting in different combinations of alleles.

Homologous chromosomes replicate their DNA and switch positions before lining up during metaphase.
Homologous chromosomes replicate their DNA and switch positions before lining up during metaphase.

DNA fragments break off from chromosomes and attach to the ends of other chromosomes, resulting in different gene sequences.
DNA fragments break off from chromosomes and attach to the ends of other chromosomes, resulting in different gene sequences.

Answer 1

Correct answer:
- Homologous chromosomes exchange DNA segments, resulting in different combinations of alleles.

Brief explanation:
- Crossing over occurs in prophase I of meiosis between non‑sister chromatids of homologous chromosomes. They physically exchange corresponding DNA segments, creating new allele combinations on each chromosome and increasing genetic diversity among gametes.
- The other choices are incorrect: sister chromatids are identical (so they don’t create new allele combinations by exchanging); “replicate and switch positions” confuses replication/independent assortment with crossing over; and breaking/reattaching fragments describes rare chromosomal rearrangements (translocations), not normal crossing over.