AP BIOLOGY

Detailed explanation-1: -During meiosis, homologous chromosomes (1 from each parent) pair along their lengths. The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.

Detailed explanation-2: -Answer and Explanation: The sources of genetic variation during meiosis are random sorting of homologous chromosomes and sister chromatids as well as the process of crossing over.

Detailed explanation-3: -The crossover events are the first source of genetic variation produced by meiosis. A single crossover event between homologous non-sister chromatids leads to an exchange of DNA between chromosomes.

Detailed explanation-4: -Crossing over is important for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.

Detailed explanation-5: -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.