Biology means STUDY OF LIFE.
1. Cellular and Organismal Biology - here the focus is on the cell itself, and how the organelles in the cell work together to undergo the basic processes of life.
2. Microbiology - here the focus is on microorganisms (unicellular or cell-clustered organisms), and how they interact with the environment. This also includes the study of viruses, bacteria, and mycology (fungus).
3. Ecology - here the focus is on distributions and relations of organisms and their interactions with each other in a common environment; the interaction between living things and the environment.
4. Genetics/Evolution - here the focus is on tracing a gene pool through generations and determining how that gene is affecting that organism and its interaction in the world; evolution ties into every concept of biology but best fits into genetics as most of the time evolution is caused by a genetic mutation.
5. Zoology - here the focus is on animals; their structure, function and behavior all comes into play.
6. Botany - here the focus is on plants; their structure, function, and interaction with the environment all comes into play