AP BIOLOGY

Detailed explanation-1: -If nondisjunction occurs during Meiosis I in humans, two gametes with extra chromosomes will be produced (24 chromosomes each, or n+1) and two gametes lacking a chromosome will be produced (22 chromosomes each, n-1).

Detailed explanation-2: -Nondisjunction of chromosome 21 is the leading cause of Down syndrome. Two risk factors for maternal nondisjunction of chromosome 21 are increased maternal age and altered recombination.

Detailed explanation-3: -In this example, a diploid body cell contains 2n = 4 chromosomes, 2 from mom and two from dad.

Detailed explanation-4: -Klinefelter’s syndrome, XXY males, can occur due to nondisjunction of X chromosomes during prophase of meiosis I in females. One of the eggs from such a meiosis could receive both X chromosomes, and the other would receive no X chromosomes.

Detailed explanation-5: -Nondisjunction is defined as the failure of chromosomes or chromatids to segregate during cell division. It leads to daughter cells with abnormal numbers of chromosomes, which is known as aneuploidy.