AP BIOLOGY

Detailed explanation-1: -Egg and sperm cells have just 23 chromosomes each. That’s half as many chromosomes as regular cells. Through the process of fertilization, egg and sperm join to make a cell with 46 chromosomes (23 pairs), called a zygote. For each chromosome pair, one homologous chromosome came from each parent.

Detailed explanation-2: -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-3: -Humans have 46 chromosomes in all their somatic cells (body cells: all cells other than sex cells). Thus, the body cells have both the sets of chromosomes i.e. they are diploid. But the sex cells, egg and sperm, are haploid ie. only one set of chromosomes is present in them.

Detailed explanation-4: -Humans typically have 23 pairs of chromosomes, or 46 chromosomes in total. Chromosomes are made up of long strands of DNA, which contain all the body’s genes.

Detailed explanation-5: -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.