Monera is the taxonomic cluster which is in vogue these days. There were five biological kingdoms existed, Monera kingdom was believed as one of them. This kingdom consists of bacteria. There may be a plethora of them, but all of them reside in monera kingdom. These bacteria may be proven to be harmful in some cases but some of them actually work in the favor of human beings. Most of the prokaryotic organisms, which do not have any nucleus, were included in this kingdom. The microscopic organisms were attempted to be incorporated with any of the kingdoms i.e. animal or plant. But considering the fabrication of the cellular substances, the kingdoms are divided into different classifications rather than allowing for animal or plant categorization. The kingdoms like eukaryotic and prokaryotic is divided according to the presence of nucleus and other individualities but in case of Monera, the uniqueness was the topic of controversy since a long ago. Some scientists identified Monera as per its phylogeny but this proposal was not accepted unanimously. Robert Whittaker anticipated as five kingdoms exists as per biological classification and they are Plantae, Eukaryotic fungi, Eukaryotic Protista, Animalia and Prokaryotic Monera.

The cell absorbs the digested nutrients inside it. Some of the prokaryotic cells arrange itself by the way it metabolize the nutrients. Organic composite is produced by Autotrophs. But Heterotrophs depends on auxiliary resources thus acquires oomph. Symbiotic association is maintained by some bacteria classes. But the host is harmed by parasitism. On the other hand both are benefited with mutualism. And the host remains unharmed in case of commensalisms. Diffusion is used by the members of the monera kingdom for digesting the nutrients.

The feature respiration is different for each member. Oxygen is needed to live in case of obligate aerobes. But in case of obligate anaerobes, the entity dies within attendance of oxygen. So that different characters are seen in respect of respiration.

George Fox and Carl Woese established that bacteria does not resembles to the archaea according to their specifications in the year 1977. They proposed that Archaea (often called Archaebacteria) and Bacteria (often called Eubacteria) should take the place of the single Prokaryotic Monera kingdom. But it was not received by Thomas Cavalier-Smith as he believed that Archaea was not that different from bacteria, it is a subpart of that realm. This is how monera kingdom became a controversial topic among the scientists.