Biology literally means the study of life, and life is pretty gosh-darn complex. There are so many different types of living organisms, many different types of environments, millions of different combinations of genetic material. All the information related to studying living things falls under biology, but a biologist does not and cannot study every facet of all living things. It would just take too much time. So, biologists specialize in certain areas of biology and focus their research. With each specialist studying details of certain biological areas, the information can be pooled (usually at big conferences) and shared to make the knowledge base a bit wider. And that's what science is: a continually growing knowledge base focused on things in nature, whether those natural things are banana trees, kangaroos, swordfish, dinosaurs, rocks, gases, or chemicals and cells that make up all of those things.

Biology is the branch of science that deals with living organisms. Chemistry focuses on the chemicals that comprise matter. Physics focuses on the laws that Mother Nature set for all matter: living and nonliving.