|Organization for the Advancement of
|Introduction to Biology
The science of biology is, simply put, the study of life in nature. Biology is concerned with various
properties of life including the characteristics and behaviors of organisms, the steps that elicit new forms
of life and new species, and the interactions that life forms have with their environment. Biology
encompasses a myriad of academic disciplines that are often viewed as independent fields.
For matter to be considered biological, it must be alive. Any physical matter that is arranged into a
biological cell is considered a form of life. This includes both single cells and multicellular organisms.
Viruses for example, do contain genetic material and have many characteristics in common with some
forms of life, however, they are not considered to be alive because they are not cellular in structure. Life is
generally divided into 5 distinct kingdoms: Protista, Monera, Fungi, Plantae and Animalia. If it is alive on
the Earth, it must fall into one of these categories. Each of these five kingdoms contain six other
distinctions that classify animals by their taxonomic properties. The seven classifications are:
Starting with the kingdom and ending with the species, these categories become increasingly specific.
Every form of life can be classified, by certain specified criteria, under each one of these distinctions.
Biology classifies life and also analyzes it on many different scales:
• at the atomic or molecular scale through molecular biology and biochemistry
• at the cellular scale through cell biology
• at the multicellular scales through anatomy and physiology
• at the developmental level of an individual organism through ontology
• at the level of heredity between parent and offspring through genetics
• at the level of group behavior through ethology
• at the level of interdependent populations and their habitats through ecology
• at the level of evolutionary change of populations through phylogeny and evolutionary biology
• at the level of speculation concerning life outside of earth through exobiology