AP BIOLOGY

Detailed explanation-1: -Each person normally has one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells.

Detailed explanation-2: -Every egg has an X sex chromosome; a sperm can have either an X or a Y sex chromosome. If the sperm that fertilizes an egg has an X chromosome, the baby is female; if it has a Y chromosome, the baby will be a boy.

Detailed explanation-3: -Humans and most mammals have two sex chromosomes, the X and Y. Females have two X chromosomes in their cells, while males have X and Y chromosomes in their cells. Egg cells all contain an X chromosome, while sperm cells contain an X or a Y chromosome.

Detailed explanation-4: -An egg will always have an X chromosome, since the woman’s sex chromosome pair only has Xs. Sperm can have either an X chromosome or a Y chromosome. If a sperm with an X chromosome fertilizes the egg, the new cell will have two X chromosomes. One came from the father’s sperm and one came from the mother’s egg.

Detailed explanation-5: -Thus, a human egg cell would have 23 chromosomes. Female having XX chromosome in the 23rd pair, so human egg would be having only one X-chromosome.