Themes of Biology

Definition of Biology

Biology is the study of life, or all living things.

An individual living thing is referred to as an organism.

There are 6 main themes of biology.

1. Cell Structure and Function

The cell is the basic unit of life. Some organisms are unicellular—have only one

cell. Other organisms are multicellular—composed

of more than one cell. Cells are highly organized and contain

specialized structures that carry out different processes.

Multicellular organisms usually have differentiated cells. (Different cells perform different functions.)

2. Stability and Homeostasis

This is the ability of a cell to maintain a stable level of internal conditions.

For example, humans maintain a stable body temperature under controlled or normal conditions.

3. Reproduction and Inheritance

Reproduction—the process where organisms transmit hereditary information to their offspring.

This hereditary info. is in the form of DNA (deoxyribonucleic acid).

There are two types of reproduction: Sexual reproduction Asexual reproduction

4. Evolution

Evolution is the process of change in a population over a period of time.

Scientists suggest that this process occurs due to natural selection (the process by which organisms with favorable variations reproduce at higher rates than those without such variations).

There is both microevolution and macroevolution.

5. Interdependence of Organisms

Ecology studies the interactions of organisms with each other and their environments.

6. Matter, Energy, and Organization

Living things are highly organized structures that must be maintained in their orderly state by a constant supply of energy. How organisms obtain, use, and transfer energy is a major portion of the study of biology.

Organisms obtain their energy by either being heterotrophs or autotrophs.