AP BIOLOGY

Detailed explanation-1: -Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes’ non-sister chromatids that results in recombinant chromosomes.

Detailed explanation-2: -chiasmata) is the point of contact, the physical link, between two (non-sister) chromatids belonging to homologous chromosomes. At a given chiasma, an exchange of genetic material can occur between both chromatids, what is called a chromosomal crossover, but this is much more frequent during meiosis than mitosis.

Detailed explanation-3: -The chiasma is a structure that forms between a pair of homologous chromosomes by crossover recombination and physically links the homologous chromosomes during meiosis.

Detailed explanation-4: -When homologous chromosomes form pairs during prophase I of meiosis I, crossing-over can occur. Crossing-over is the exchange of genetic material between homologous chromosomes. It results in new combinations of genes on each chromosome.

Detailed explanation-5: -During meiosis, crossing-over occurs at the pachytene stage, when homologous chromosomes are completely paired. At diplotene, when homologs separate, the sites of crossing-over become visible as chiasmata, which hold the two homologs of a bivalent together until segregation at anaphase I.