Cell Theory:

1. Cells are the basic building blocks of all living things.
2. All life activities take the place of cells.
3. New cells are produced by existing cells.


What determines if something is "alive"?

ALL living things must have all of the following characteristics:
1. They must have the ability to acquire and use energy.
2. They must have the ability to reproduce.
3. They must have the ability to respond to the outside world.
4. They must have the ability to get rid of waste.
5. All living things are made of cells.

Some biologists also add movement, growth and life span to the list.