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In biology, taxonomy (from Ancient Greek τάξις () ' arrangement ' and -νομία () ' method ') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics.
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank [1] because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a taxon) in a hierarchy that reflects evolutionary
Biological organisation is the organisation of complex biological structures and systems that define life using a reductionistic approach. [1] The traditional hierarchy, as detailed below, extends from atoms to biospheres .
The hierarchy of biological classification's eight major taxonomic ranks.A domain contains one or more kingdoms. Intermediate minor rankings are not shown. In biology, a kingdom is the second highest taxonomic rank, just below domain.
In biological phylogenetics, a clade (from Ancient Greek κλάδος (kládos) ' branch '), also known as a monophyletic group or natural group, [1] is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. [2]
Groups of atoms that contain these elements (O-, H-, P-, and S-) and are bonded to a central carbon atom or skeleton are called functional groups. [33] There are six prominent functional groups that can be found in organisms: amino group , carboxyl group , carbonyl group , hydroxyl group , phosphate group , and sulfhydryl group .
With the development of these three techniques, the field of structural biology expanded and also became a branch of molecular biology, biochemistry, and biophysics concerned with the molecular structure of biological macromolecules (especially proteins, made up of amino acids, RNA or DNA, made up of nucleotides, and membranes, made up of ...
A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales, and the forelegs of four-legged vertebrates like horses and crocodilians are all derived from the same ancestral tetrapod structure. In developmental biology, organs that developed in ...