Organisms are the first level of organization, it is any living system such as an animal, plant, fungus or bacterium. An organism is also defined as a living system that is capable of responding to stimuli, reproduction, homeostasis and growth and development.
Population
Populations are the second level of organization, it is all the same species who live together in a particular geographical area with one another. In order to be a population, the group must also be able to interbreed with each other.
Community
A community is the third level of organization, It consists of two or more different populations which live and occupy the same environment at the same time,
Ecosystem
An ecosystem is the fourth level of organization, it consists of all the communities within a certain area which includes all the biotic (living) and abiotic (nonliving) things in that area.
Biosphere
The biosphere is the last level of organization. It is all the ecosystems put together on a global level. It is the integration of all the living beings and their interaction with each other.