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Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction.
A tree of life, like this one from Charles Darwin's notebooks c. July 1837, implies a single common ancestor at its root (labelled "1").. A phylogenetic tree directly portrays the idea of evolution by descent from a single ancestor. [3]
Biology is the scientific study of life. [ 1 ] [ 2 ] [ 3 ] It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. [ 1 ] [ 2 ] [ 3 ] For instance, all organisms are composed of at least one cell that processes hereditary information encoded in genes , which can be transmitted ...
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
The key to life history theory is that there are limited resources available, and focusing on only a few life history characteristics is necessary. Examples of some major life history characteristics include: Age at first reproductive event; Reproductive lifespan and ageing; Number and size of offspring
In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization , from kingdoms to species , and individual organisms and molecules , such as DNA and proteins .
Life is divided into domains, which are subdivided into further groups. Intermediate minor rankings are not shown. Intermediate minor rankings are not shown. In biological taxonomy , a domain ( / d ə ˈ m eɪ n / or / d oʊ ˈ m eɪ n / ) ( Latin : regio [ 1 ] ), also dominion , [ 2 ] superkingdom , realm , or empire , is the highest taxonomic ...
The tree of life or universal tree of life is a metaphor, conceptual model, and research tool used to explore the evolution of life and describe the relationships between organisms, both living and extinct, as described in a famous passage in Charles Darwin's On the Origin of Species (1859). [1]