AP BIOLOGY

Detailed explanation-1: -Crossing over is a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes-one from the mother and one from the father-line up, parts of the chromosome can be switched. The two chromosomes contain the same genes, but may have different forms of the genes.

Detailed explanation-2: -Crossing over is an enzyme-mediated process, where the exchange of genetic material between non-sister chromatids of homologous chromosomes takes place. It occurs at the pachytene stage of prophase I of meiosis.

Detailed explanation-3: -During synapsis, homologous chromosomes physically connect at crossing points called chiasma. At each chiasma, genetic recombination between maternal and paternal homologous chromosomes occurs in a process called crossing over.

Detailed explanation-4: -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.

Detailed explanation-5: -Genetic recombination is a process that occurs during meiosis, which is the type of cell division that produces gametes. During this process, homologous chromosomes pair up and form a unit called a tetrad. The chromosomes can then cross over and exchange genetic material, which results in new combinations of alleles.