In order to identify living organisms, scientists listed 7 characteristics which all living organisms have:
1. Nutrition:
Taking in nutrients which are organic substances and mineral ions, containing raw materials and energy for growth and tissue repair, absorbing and assimilating them.
2. Excretion:
Removal from organisms of toxic materials, the waste products of metabolism and substances in excess.
3. Respiration:
Chemical reactions that break down nutrient molecules in living cells to release energy.
4. Sensitivity:
The ability to detect or sense changes in the environment and to make responses.
5. Reproduction:
Progresses that make more of the same kind of organism.
6. Growth:
The permanent increase in size and dry mass by an increase in number of cells, cell size, or both.
7. Movement:
An action by an organism or part of an organism that changes position or place.
The seven characteristics could be memorized by the term “Mrs. Gren”:
| Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition |  |
Definitions:
Metabolism:
Chemical reactions taking place in cells.
Stimuli:
Changes in the environment which organisms response to.