Question

Are bacteria plants, or are they a seperate lifeform group entirely?

All life on Earth (with the possible exception of the viruses) share the same biochemistry and presumably are descended from a common ancestor. In this sense, bacteria and plants are not separate lifeforms. However, they appear at different levels in the universal tree of life (see discussions of "tree of life" and "weose, carl" and "taxonomy" in Wikipedia). The highest level classification of life is into three Domains: Bacteria, Archaea, and Eukaria. Within the Eukaria (cells with nuclei) there are several Kingdoms, including protists, fungi, plants, and animals. Thus bacteria are not plants, and plants are not descended from bacteria. The line of eukaria that includes plants diverged from the bacteria very early in the history if life on Earth. However, there has undoubtedly been exchange of genetic material -- what is called lateral gene transfer -- between bacteria and single-celled eukaria. Photosynthesis was "invented" by the bacteria, and the cyanobacteria are still a dominant form of photosynthetic life (and hence a major source of oxygen in the Earth's atmosphere). David Morrison
NAI Senior Scientist
July 31, 2007