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 from a Public Domain Retrieved from Wikimedia Commons. Explanation of Classification: Domain and Kingdom: Escherichia coli fits into the domain and kingdom of Bacteria because members of this group are unicellular microorganisms.lass: Escherichia coli fits into the class Gamma Proteobacteria because members of this group are. Order: Escherichia coli fits into the order Enterobacteriales because members of this group are rod-shaped facultatively anaerobic G-bacterium.