INTRODUCTION TO BIOLOGY Levels of Organization

Atom The basic unit of all matter

Molecule Group of two or more atoms held together by chemical bonds

Cell The basic unit of living things

Tissue Group of cells of the same type

Organ Structure composed of two or more tissues that work together to perform a specific function

Organ System Group of organs that work together to perform certain functions

Organism Individual living thing made up of several organ systems

Population Group of organisms of the same species that live together in a particular location

Community Group of distinct populations that live in a particular location

Ecosystem All the communities and the non-living parts in a particular location

Biome A group of ecosystems that have the same climate and similar communities

Biosphere Part of the earth where all life exists and includes the land, water and air or atmosphere