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All known living things are made up of one or more cells [13] All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. [14] The activity of an organism depends on the total activity of independent cells. [15] Energy flow (metabolism and biochemistry) occurs ...
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. All life over time eventually reaches a state of ...
686465. Anatomical terminology. [edit on Wikidata] The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'.
Cell theory states that cells are the fundamental units of life, that all living things are composed of one or more cells, and that all cells arise from preexisting cells through cell division. [40] Most cells are very small, with diameters ranging from 1 to 100 micrometers and are therefore only visible under a light or electron microscope. [41]
Different kinds of living creatures studied in life sciences top: microorganisms (E. coli bacteria) and an animal (Goliath beetle) bottom: a plant (tree fern) and humans Science Outline Category Article indexes Glossaries History Literature Philosophy Fields (Outline / List) Scientific fields Formal sciences Mathematical Computer Natural sciences Physical Life sciences Behavioural sciences ...
Phylogenetic tree linking all major groups of living organisms, namely the Bacteria, Archaea, and Eukarya, as proposed by Woese et al 1990, [ 1 ] with the last universal common ancestor (LUCA) shown at the root. The last universal common ancestor (LUCA) is the hypothesized common ancestral cell from which the three domains of life, the Bacteria ...
Contents. Evidence of common descent. Evidence of common descent of living organisms has been discovered by scientists researching in a variety of disciplines over many decades, demonstrating that all life on Earth comes from a single ancestor. This forms an important part of the evidence on which evolutionary theory rests, demonstrates that ...
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 ...