Evolution - The change in heritable traits in a population of organisms over successive generations.⏎
Contagion - A general term for any disease-causing infectious agent spread by direct or indirect contact.⏎
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.⏎
Exoskeleton - An external skeleton that protects and supports an organism, in contrast to an internal endoskeleton.⏎
Cirrhosis - A condition caused by chronic liver disease characterized by the development of scar tissue leading to a loss of liver function.⏎