immune system, n the group of organs, cells, and chemicals that protect the body from harmful viruses, bacteria, and abnormal cells. It includes bone marrow, proteins, the thymus, the spleen, the lymphocytes, and other white blood cells.
50% from each parent: one allele in each gene, each parent, for a total of two. 2 people found this useful. Edit. Share to: 1  College Admission Interview Dos and Don'ts Some colleges offer applicants the opportunity to interview on campus or close to home.
In the case of humans, this means that parent cells have two chromosomes and gametes have one. During fertilization, gametes from the sperm combine with gametes from the egg to form a zygote. The zygote contains two sets of 23 chromosomes, for the required 46. All of the gametes in the motherâs eggs possess X chromosomes. The fatherâs sperm contains about half X and half Y chromosomes. The sperm are the variable factor in determining the sex of the baby.