Characteristics of living organisms: There are more than 2 million kinds of life on Earth that are known to scientists. All of these characteristics are found in each living thing, which is called an “organism”.

1. Living organisms are highly organized and complex entities having many complex chemical substances.
2. They are made up of cells, either one or more. A cell is the smallest unit, said to be alive.
3. They contain a genetic program that works for their characteristics.
4. They can acquire and use energy.
5. They carry out and control numerous chemical reactions, which become the basis of all of their characteristics.
6. They can grow and attain a definite form and size.
7. They maintain or try to maintain a constant internal environment of their bodies.
8. They respond to changes in the environment and so remain or try to remain adapted to their environment.
9. They produce offspring similar to themselves.
10. They are not eternal and have a limited life span.