The smallest fundamentalunit of structure and function in living organisms.

Groups of similar cells carrying out similar or related functions.

Collections of tissues grouped together performing a common function

A higher level of organization that consists of functionally related organs

A living thing that has an organized structure, can react to stimuli, reproduce, grow, adapt, and maintain homeostasis.

Consists of all the organisms of a given species that live in a particular area.

All of the populations of different species that live in the same area and interact with one another.

Includes the living organisms (all the populations) in an area and the non-living aspects of the environment.  It describes two or more communities.

"The world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment"

A global ecosystem composed of living organisms (biota) and the abiotic (nonliving) factors from which they derive energy and nutrients. It is any part of Earth where living organism are found.