Kingdom: Monera - SS1 Biology Lesson Note

Monera is a biological kingdom that was once recognized in the five-kingdom classification system proposed by biologist Robert Whittaker in the 1960s. However, the kingdom Monera is no longer considered valid in modern classification systems.

Previously, the kingdom Monera encompassed all prokaryotic organisms, which are organisms lacking a true nucleus and membrane-bound organelles. It included two major groups: bacteria (also known as eubacteria) and archaea (formerly called archaebacteria).

Bacteria are widespread and diverse microorganisms that can be found in various habitats, including soil, water, and the human body. They have distinct cell walls and can be classified based on their shape (e.g., rod-shaped bacteria called bacilli, spherical bacteria called cocci, and spiral-shaped bacteria called spirilla).

Image from microbeonline.com

 Image from brainkart.com

Archaea are a group of single-celled microorganisms that are distinct from bacteria in terms of their genetics, biochemistry, and ability to thrive in extreme environments. They are known for their ability to survive in extreme conditions such as high temperatures, high salinity, and acidic environments.

While the kingdom Monera was once considered a valid taxonomic classification, advancements in molecular biology and genetic research have revealed significant differences between bacteria and archaea. Consequently, the three-domain system has been widely accepted, classifying organisms into three domains: Bacteria, Archaea, and Eukarya. This revised system recognizes the fundamental differences between prokaryotic organisms (Bacteria and Archaea) and eukaryotic organisms (Eukarya).