Which kingdom is considered the most primitive and consists of prokaryotic organisms?

The kingdom that is considered the most primitive and consists of prokaryotic organisms is Monera. Organisms in this kingdom are characterized by the absence of a nucleus and other membrane-bound organelles, which are distinctive features of prokaryotic cells. Monera includes bacteria and archaea, which are some of the simplest and earliest forms of life on Earth.

This kingdom is foundational to the understanding of biological classification, as it represents a significant evolutionary step before the emergence of more complex eukaryotic organisms found in the other kingdoms such as Plantae, Animalia, and Fungi. Each of these kingdoms consists of eukaryotic organisms that have cells with a defined nucleus and various organelles, indicating a more advanced level of cellular organization compared to the prokaryotic organisms in Monera.