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Organism. An organism is defined in a medical dictionary as any living thing that functions as an individual. [1] Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism.
Organ (biology) In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. [ 1] In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which ...
Minor intermediate ranks are not shown. A species ( pl.: species) is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. [ 1] It is the basic unit of classification and a taxonomic rank of an organism, as well as a ...
e. In biology, taxonomy (from Ancient Greek τάξις ( taxis) 'arrangement' and -νομία ( -nomia) ' method ') is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic ...
v. t. e. A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells . The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India.
They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust.
Model organism. A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...