Fertilized Egg - Sometimes referred to as a zygote, this is the resulting initial cell formed when a sperm cell unites with an egg cell.⏎
Genetics - A branch of biology that studies heredity and variation in organisms.⏎
Gene - The physical and functional unit of heredity made up of DNA. Every individual has two copies of each gene, one inherited from the mother and the other from the father.⏎
Ecology - A branch of science that deals with the relation of organisms to one another and their physical environment.⏎
Contagion - A general term for any disease-causing infectious agent spread by direct or indirect contact.⏎