Biology explores life from the global to the microscopic scale. Biology explores life in its diverse forms.

The Biosphere  Biosphere – consists of all the parts of the planet that are inhabited by living things.  Includes most regions of land, bodies of water, and the atmosphere up to several kilometers.

Ecosystems  Ecosystem – community of living things in an area, along with nonliving features that support the environment.  Earth’s ecosystems vary widely.

Organisms  Organisms – individual living things.  Some organisms are too small to see with the naked eye.  Interactions among the organisms of a community make each ecosystem a constantly changing place.

Cells  Cell – life’s basic unit of structure and function.  All organisms are made up of one or more cells.

DNA and Genes  DNA – chemical responsible for inheritance.  DNA contains all the instructions for a cell to make all the other molecules it needs to function.  Genes – inherited information on the DNA molecule.

Life’s Diversity of Species  Each different kind of organism you observe is an example of a species, a distinct form of life.  Identified more than 1.5 million species.

The Three Domains of Life  Domain – broadest category of classification.  Three domains: Archaea, Bacteria, and Eukarya.  Most organisms in Archaea and Bacteria are very tiny and unicellular, single celled.

 They have cells without nuclei and are therefore prokaryotic cells.  Eukaryotic cells contain nuclei.  Multicellular organisms are made of many cells, such as humans.