How does crossing over during meiosis contribute to genetic variation?

How does crossing over during meiosis contribute to genetic variation?

• A. DNA is replicated.
• B. RNA is transcribed.
• C. Homologous chromosomes exchange segments, creating new allele combinations not present in the parent.
• D. Chromatids separate without recombination.

Answer: (C)

Crossing over shuffles genetic material between paired homologous chromosomes during meiosis I. When chromosome segments are exchanged at the points where homologs align, the resulting chromatids have new combinations of alleles that weren’t present in either parent. This recombination creates diversity among the gametes, which can then be passed to offspring. DNA replication happens before meiosis, not as the mechanism that creates new allele combinations during crossing over. RNA transcription is about copying DNA into RNA for gene expression and is not part of generating variation through crossing over. If chromatids separate without recombination, no new allele combinations are created, so this would not contribute to variation.

Crossing over shuffles genetic material between paired homologous chromosomes during meiosis I. When chromosome segments are exchanged at the points where homologs align, the resulting chromatids have new combinations of alleles that weren’t present in either parent. This recombination creates diversity among the gametes, which can then be passed to offspring.

DNA replication happens before meiosis, not as the mechanism that creates new allele combinations during crossing over. RNA transcription is about copying DNA into RNA for gene expression and is not part of generating variation through crossing over. If chromatids separate without recombination, no new allele combinations are created, so this would not contribute to variation.