During meiosis, what process involves the exchange of chromosome segments between homologous chromosomes?

During meiosis, what process involves the exchange of chromosome segments between homologous chromosomes?

• A. Crossing-over
• B. Independent assortment
• C. Replication
• D. Mutation

Answer: (A)

Crossing-over is the exchange of chromosome segments between homologous chromosomes during prophase I of meiosis. Here, homologous chromosomes pair up and form a tetrad, and non-sister chromatids swap segments at locations called chiasmata. This genetic recombination creates new allele combinations on each chromosome, increasing variation in the gametes produced. Replication, the copying of DNA before meiosis, is not the exchange event. Mutation refers to a change in the DNA sequence, not a deliberate segment swap between homologs. Independent assortment describes how chromosome pairs orient and separate randomly during metaphase I, which also contributes to variation but does not involve exchanging chromosome segments.

Crossing-over is the exchange of chromosome segments between homologous chromosomes during prophase I of meiosis. Here, homologous chromosomes pair up and form a tetrad, and non-sister chromatids swap segments at locations called chiasmata. This genetic recombination creates new allele combinations on each chromosome, increasing variation in the gametes produced.

Replication, the copying of DNA before meiosis, is not the exchange event. Mutation refers to a change in the DNA sequence, not a deliberate segment swap between homologs. Independent assortment describes how chromosome pairs orient and separate randomly during metaphase I, which also contributes to variation but does not involve exchanging chromosome segments.