Taxonomy refers to the science of classification of living organisms. The five KingdomClassification system was widely used from 1920 to 1980.eukaryoticeukaryoticeukaryoticmulticellularmulticellularmulticellularabsorbphotosynthesizenonmotileingestmotilenonmotilesexualsexualsexualAnimalsFungiPlantseukaryoticunicellularor multicellularabsorb, ingest, orphotosynthesizesexual and asexualProtists00prokaryoticabsorb andphotosynthesizemotile or nonmotileRobert Harding Whittaker(1920 - 1980)MoneraasexualExplain why this classification system was abandoned in favor of the 3-domain system.

The most recent classification scheme is the three-domain classification with six kingdoms. Carl Woese first proposed it in 1990. Archaea, bacteria, and eukaryotes are the three domains of this system. Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia are the six kingdoms. The kingdom Archaebacteria is a recent addition to RH Whittaker's prior five-kingdom categorization. -Highly conserved proteins have inconsistencies in the sequence of characteristics and polygenes. - Gram-negative bacteria and archaea both have monoderm, however they belong to separate groups.The three-domain classification is based on three separate characteristics: 16 S ribosomal RNA (ribonucleic acid) sequencing, cell membrane structural variations, and antibiotic sensitivity. Because 16 S rRNA evolves slowly and is universally the same, it was a superior option than DNA.All prokaryotes, unicellular creatures without a nuclear membrane, are classified as archaea in the first domain. The cell wall of archaea differs from that of eubacteria in that it lacks peptidoglycan (polysaccharide). Their cell walls contain pseudomurein. They are ancient bacteria that can survive in harsh environments such as saline marshes (halophiles), geothermal hot springs (thermophiles), and freezing temperatures (psychrophilic),The Eubacteria, or real bacteria with peptidoglycan in their cell walls, make up the second domain. Gram-negative bacteria, on the other hand, have a comparable cell wall composition to Archaebacteria but are classified in a separate domain, which is one disadvantage of this categorization. All eukaryotes with a membrane-bound nucleus belong to the third domain. Protists like Euglena, fungi like mushrooms, plants, and animals are among them.