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Passive versus active trends in complexity. Organisms at the beginning are red. Numbers are shown by height with time moving up in a series. If evolution possessed an active trend toward complexity (orthogenesis), as was widely believed in the 19th century, [12] then we would expect to see an active trend of increase over time in the most common value of complexity among organisms.
Biocomplexity spiral 'Biocomplexity' is a multidisciplinary field that examines and investigates emergent properties arising from the interaction of multiple biological agents, phenomena, and systems, which may range in spatiotemporal scales, biological relationships,interactions and levels from molecules to ecosystems.
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]
Smaller organisms, including prokaryotes (bacteria and archaea), consist of small single cells. Larger organisms, mainly eukaryotes, can consist of single cells or may be multicellular with more complex structure. Life is only known to exist on Earth but extraterrestrial life is thought probable.
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 ...
Digestion: The physical breakdown of complex large and organic food particles and the enzymatic breakdown of complex organic compounds into small, simple molecules. Absorption: The active and passive transport of the chemical products of digestion out of the food-containing compartment and into the body; 4.
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each other, further blurring any distinctions.
A small fraction of the genes in an organism's genome called the developmental-genetic toolkit control the development of that organism. These toolkit genes are highly conserved among phyla, meaning that they are ancient and very similar in widely separated groups of animals. Differences in deployment of toolkit genes affect the body plan and ...