Two Important Life Science Theories
In the many life sciences, there are possibly hundreds or thousands of theories. Yet there
are at least two fundamental theories, which provide a foundation for modern biology. They
are:
- The Cell Theory
- The Theory of Evolution
The Cell Theory
The Cell Theory states that:
- All organisms are composed of cells (Figure1.10).
- Cells are the basic units of structure and function in an organism.
- Cells only come from preexisting cells; life comes from life.
Figure 1.10: The two types of cells, eukaryotic (left) and prokaryotic (right). ( 10 )The development of the microscope in the mid 1600s made it possible to come up with this
theory (Figure1.11).
The Theory of Evolution
In biology, evolution is the process of change in the inherited traits of a population of
organisms over time. Natural selection is the process where organisms that are better suited
to the environment are more likely to survive and reproduce than others that are less suited
to the environment. This theory basically states that better suited organisms live longer
and have an easier time reproducing, passing on their traits that made them better suited