AP BIOLOGY

Detailed explanation-1: -Crossing over generally takes place at the pachytene stage of prophase I of Meiosis I. During the pachytene, stage one chromatid of each homolog overlaps or crosses over a corresponding non-sister chromatid of the other homolog at one or more points. These crossing points are called chiasma.

Detailed explanation-2: -Explanation: Crossing over occurs when chromosomal homologs exchange information during metaphase of Meiosis I. During this stage, homologous chromosomes line up on the metaphase plate and exchange genetic information.

Detailed explanation-3: -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.

Detailed explanation-4: -Crossing over does not occur in mitosis. Crossing over occurs in anaphase at each pole of the cell where the chromosomes are packed together. Crossing over occurs in metaphase when all the chromosomes are aligned in the middle of the cell. Their close proximity allows crossing over to occur.

Detailed explanation-5: -In meiosis I, chromosomes in a diploid cell resegregate, producing four haploid daughter cells. It is this step in meiosis that generates genetic diversity.