A group of organ systems working together that has a distinct existence as a complex, self reproducing unit

A group of freely interacting and breeding individuals of the same species

All the populations of different species living and interacting together in a distinct area

All of the living (biotic) and all of the physical nonliving factors (abiotic) in an area

The region on, below, and above the Earth's surface where life exists

Large region with typical plants and animals that includes several ecosystems