Biology is often classified or
studied depending on the scale of the living thing but also on the
types of
living things.
For example the
study of the very small parts like the individual
chemicals of living
systems is often refered to as
biochemistry. But then this can be
specified further to a particular creature or type
of biological thing. For example the biochemistry
of frogs would be concerned with the chemicals that
frogs produce or are special to them.
The next level up
from chemicals is looking at large groups of
chemicals or molecules
that make up living things. For example
looking at what molecules cells are made of and the
shapes of proteins is called molecular
biology.
Further up the
level are biological tissues, like skin, muscles.
This then leads to up to whole organs like the
liver, or kidneys or brains. Then biology considers
the whole organism. For example the biology human
beings, biology of fish biology of mammals.
But it doesn't
stop there. Biology looks at the interactions of
groups of organisms with each other and with their
environments.