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But despite the development from two kingdoms to five among most scientists, some authors as late as 1975 continued to employ a traditional two-kingdom system of animals and plants, dividing the plant kingdom into subkingdoms Prokaryota (bacteria and cyanobacteria), Mycota (fungi and supposed relatives), and Chlorota (algae and land plants). [14]
[7] [24] The latter classification system was widely followed, in which Robert Whittaker proposed a five kingdom system for classification of living organisms. [24] Whittaker's system placed most single celled organisms into either the prokaryotic Monera or the eukaryotic Protista.
By 1998, Cavalier-Smith had reduced the total number of kingdoms from eight to six: Animalia, Protozoa, Fungi, Plantae (including red and green algae), Chromista, and Bacteria. [44] Five of Cavalier-Smith's kingdoms are classified as eukaryotes as shown in the following scheme: Eubacteria; Neomura. Archaebacteria; Eukaryotes. Kingdom Protozoa
Kingdom Protista (or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all eukaryotes that are not plants, animals, or fungi. [16]: 120 Protista is a paraphyletic taxon, [47] which is less acceptable to present-day biologists than in the past.
These organisms exploit a proton gradient to generate adenosine triphosphate (ATP), a mechanism used by virtually all subsequent organisms. [38] [39] [40] 3000 Ma Photosynthesizing cyanobacteria using water as a reducing agent and producing oxygen as a waste product. [41] Free oxygen initially oxidizes dissolved iron in the oceans, creating ...
The bloodless animals were divided into five groups: cephalopods, crustaceans, insects (which included the spiders, scorpions, and centipedes), shelled animals (such as most molluscs and echinoderms), and "zoophytes" (animals that resemble plants). This theory remained dominant for more than a thousand years.
The presence of these ether linkages in Archaea adds to their ability to withstand extreme temperatures and highly acidic conditions, but many archaea live in mild environments. Halophiles (organisms that thrive in highly salty environments) and hyperthermophiles (organisms that thrive in extremely hot environments) are examples of Archaea. [1]
Robert Harding Whittaker (December 27, 1920 – October 20, 1980) was an American plant ecologist, active from the 1950s to the 1970s.He was the first to propose the five kingdom taxonomic classification of the world's biota into the Animalia, Plantae, Fungi, Protista, and Monera in 1969.