AP BIOLOGY

Detailed explanation-1: -As a cell undergoes meiosis, when homologous chromosomes line up together, they form a tetrad. Tetrads consist of two homologous chromosomes, with a total of four sister chromatids held together by a structure named the chiasmata.

Detailed explanation-2: -Explanation: The crossing over of homologous chromosomes occurs in prophase I of meiosis. Prophase I of meiosis is characterized by the lining up of homologous chromosomes close together to form a structure known as a tetrad.

Detailed explanation-3: -Between prophase I and metaphase I, the pairs of homologous chromosome form tetrads. Within the tetrad, any pair of chromatid arms can overlap and fuse in a process called crossing-over or recombination. Recombination is a process that breaks, recombines and rejoins sections of DNA to produce new combinations of genes.

Detailed explanation-4: -Meiosis is from the greek work for ‘diminuition’. A diploid nucleus contains two pairs of each type of chromosome (autosomes) together with the sex chromosomes (X and X, or X and Y). One of these chromosomes is derived from the male parent (parental chromosome) and one from the female (maternal chromosome).