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The evolution of biological complexity is one important outcome of the process of evolution. [1] Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.
Viruses have been variably classified as organisms [6] because they have been considered either very simple microorganisms or very complex molecules. Prions , never considered microorganisms, have been investigated by virologists; however, as the clinical effects traced to them were originally presumed due to chronic viral infections ...
An example of a fastidious bacterium is Neisseria gonorrhoeae, which requires blood or hemoglobin and several amino acids and vitamins to grow. [2] Other examples include Campylobacter spp. and Helicobacter spp., which are capnophilic – require elevated CO 2 – among other requirements. Fastidious organisms are not inherently "weak"—they ...
For example, matter from terrestrial autotrophs are both biotic and accessible to other organisms whereas the matter in rocks and minerals are abiotic and inaccessible. A biogeochemical cycle is a pathway by which specific elements of matter are turned over or moved through the biotic ( biosphere ) and the abiotic ( lithosphere , atmosphere ...
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
A species complex is typically considered as a group of close, but distinct species. [5] Obviously, the concept is closely tied to the definition of a species. Modern biology understands a species as "separately evolving metapopulation lineage" but acknowledges that the criteria to delimit species may depend on the group studied. [6]
Ecosystem classifications are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems: a biotic component, an abiotic complex, the interactions between and within them, and the physical space they occupy. Biotic factors of the ecosystem are living things; such as plants, animals, and bacteria ...
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 ...