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.
If each different type of egg from one mother could be fertilized by each different type of sperm from one father, they could produce zygotes with approximately 70 trillion combinations of chromosomes!