AP BIOLOGY

Detailed explanation-1: -Of the 23 chromosomes in human spermatozoa, chromosomes 13, 18, 21, X, and Y are important because higher incidence of abnormalities in these chromosomes can to lead miscarriages or live births (Pang et al., 1999, 2005, 2010; Rubio et al., 2001).

Detailed explanation-2: -Normally, each cell in the human body has 23 pairs of chromosomes (46 total chromosomes).

Detailed explanation-3: -The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half-from 46 to 23-to form sperm and egg cells.

Detailed explanation-4: -Healthy humans have 46 chromosomes, 23 from the sperm and 23 from the egg. An embryo with the wrong number of chromosomes is usually miscarried, or develops disorders such as Down’s syndrome, which is caused by an extra copy of chromosome 21.