As per R H Whittaker's five kingdom classification, all the prokaryotic organisms (bacteria, blue-green algae) are placed under the Kindom Monera.The general characteristics of Kingdom Monera include;All are primitive prokaryotic organisms.They are generally unicellular.A membrane-bound nucleus is absent. Double-stranded DNA is suspended in the cytoplasm, known as a nucleoid.Membrane-bound organelles like mitochondria, endoplasmic reticulum, etc. are absent.Lives in anaerobic or aerobic conditions. They also survive in extreme climatic conditions like hot springs, snow, and deep oceans.They have 70S ribosomes.Most organisms have a rigid cell wall made of peptidoglycan. But, some organisms like mycoplasma even lack a cell wall.They have different modes of nutrition - autotrophic (photoautotrophs or chemoautotrophs), heterotrophic, parasitic, saprophytic, symbiotic, etc.Reproduction is mainly asexual through binary fission or budding. Some modes of sexual reproduction like conjugation also exist.They may be motile (using flagella) or non-motile.