ABCTE Biology Practice Exam

The statement that describes crossing over is that homologous chromosomes exchange corresponding genes. This process occurs during prophase I of meiosis, where homologous chromosomes—chromosomes that are similar in shape and size and carry the same types of genes, but may have different alleles—pair up and physically exchange segments of their genetic material. This exchange increases genetic diversity by producing new combinations of alleles in the resulting gametes, which is a fundamental aspect of sexual reproduction and evolution.

Crossing over is distinct from other processes like independent assortment, which refers to the random distribution of chromosomes into gametes, and it is also different from the transfer of genetic material between nonhomologous chromosomes. Additionally, the insertion of extra bases during transcription refers to a distinct process involving the synthesis of RNA from a DNA template, which is unrelated to the genetic exchange occurring during meiosis.