Changes

[[Image:Life Six Kingdoms.png|thumb|right|300px|''The Six Kingdoms of Life'' <br /> Eddideigel 2005, WikiMedia Commons]]

[[Image:Tree_of_life.svg.png|thumb|right|300px|''The Tree of Life'' <br /> Eddideigel 2005, WikiMedia Commons]]

==Introduction==

==Introduction==

Infectious agents are microorganisms found in nature that are harmful to animals and plants. Most microorganisms found in nature are not harmful, however some microorganisms can cause disease and are therefore referred to as pathogenic.

Infectious agents are microorganisms found in nature that are harmful to animals and plants. Most microorganisms found in nature are not harmful, however some microorganisms can cause disease and are therefore referred to as pathogenic.