up vote 3 down vote accepted. $\pi$ is the name of the constant relating the diameter and circumferance of a circle. It's a definition, a particular constant that we thought deserved a name. $e$ happens to be the name of a constant from a particular limit. Like $\pi$, we named it because we thought it would be useful. In Physics, many, many constants have names. Gravitational constants, expansional constants, electrical constants, etc. Each is useful, but somewhat arbitrarily chosen.
Bacteria: The Monera Kingdom Bacteria are classified into two groups: Eubacteria (true bacteria) and Archaebacteria (Ancient Bacteria). They are autotrophic. 28-1 Chapter 28: Microbiology. 28-2 Viruses Viruses are noncellular, nonliving particles and therefore are not included in the classification scheme.
Photo by: Sebastian Kaulitzki. Bacteria are microscopic organisms that comprise the domain Eubacteria. A domain is the highest grouping of organisms, superseding the level of kingdom in the classical Linnaean system of biological classification.here are three domains, two of which, Eubacteria and Archaea, are composed entirely of prokaryotic organisms; the third domain, Eucarya, encompasses all other (eukaryotic) life forms, including the single-cell and multicellular protists, as well as animals, green plants, and fungi.