AP BIOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -Crossing over occurs during the pachytene stage of prophase in meiosis, however the chiasma are visible during. No worries!

Detailed explanation-3: -Crossing over takes place at the pachytene stage of prophase I of Meiosis. Crossing over includes the symmetrical division of chromatids, and the reciprocal exchange and crosswise assembly of segments between non-sister chromatids, often breaking linkage. This results in the recombination of genes.

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.