AP BIOLOGY

Detailed explanation-1: -Crossing over, as related to genetics and genomics, refers to the exchange of DNA between paired homologous chromosomes (one from each parent) that occurs during the development of egg and sperm cells (meiosis).

Detailed explanation-2: -This type of genetic recombination is called crossing over, and allows the daughter cells of meiosis to be genetically unique from one another. Crossing over can only occur between homologous chromosomes. Cells become haploid after meiosis I, and can no longer perform crossing over.

Detailed explanation-3: -For most eukaryotes, crossing over (recombination of chromosome segments between homologous chromosomes) is an essential part of meiosis I.

Detailed explanation-4: -Crossing over occurs only during prophase I. The complex that temporarily forms between homologous chromosomes is only present in prophase I, making this the only opportunity the cell has to move DNA segments between the homologous pair.