carbon cycle

n.1. Physics See carbon-nitrogen-oxygen cycle.2. Ecology The combined processes, including photosynthesis, decomposition, and respiration, by which carbon as a component of various compounds cycles between its major reservoirs—the atmosphere, oceans, soil, rocks, and living organisms.

carbon cycle

n 1. (Biology) the circulation of carbon between living organisms and their surroundings. Carbon dioxide from the atmosphere is synthesized by plants into plant tissue, which is ingested and metabolized by animals and converted to carbon dioxide again during respiration and decay 2. (General Physics) four thermonuclear reactions believed to be the source of energy in many stars. Carbon nuclei function as catalysts in the fusion of protons to form helium nuclei

car′bon cy`cle

n. 1. the biological cycle by which atmospheric carbon dioxide is converted to carbohydrates by plants and other photosynthesizers, consumed and metabolized by organisms, and returned to the atmosphere through respiration, decomposition, and the combustion of fossil fuels. 2. a cycle of nuclear transformations in stellar interiors through which hydrogen is converted into helium. [1910–15]

carbon cycle

carbon cycle

The continuous process by which carbon is exchanged between organisms and the environment. Carbon dioxide is absorbed from the atmosphere by plants and algae and converted to carbohydrates by photosynthesis. Carbon is then passed into the food chain and returned to the atmosphere by the respiration and decay of animals, plants, and other organisms. The burning of fossil fuels also releases carbon dioxide into the atmosphere.

Thesaurus

Noun	1.	carbon cycle - the organic circulation of carbon from the atmosphere into organisms and back againbiological process, organic process - a process occurring in living organisms
	2.	carbon cycle - a thermonuclear reaction in the interior of starsthermonuclear reaction - a nuclear fusion reaction taking place at very high temperatures (as in the sun)

Translations

ciclo del carbonio

carbon cycle

carbon cycle,

in biology, the exchange of carbon between living organisms and the nonliving environment. Inorganic carbon dioxide in the atmosphere is converted by plants into simple carbohydrates, which are then used to produce more complex substances. Animals eat the plants and are then eaten by other animals. When these life forms die, they decay, breaking down into, among many other things, carbon dioxide, which returns to the atmosphere. Plants and animals also release carbon dioxide during respirationrespiration,
process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is transported to the cells for the oxidation of organic molecules while carbon dioxide (CO₂
..... Click the link for more information. . Animals and some microorganisms require the carbon-containing substances from plants in order to produce energy and as a source of materials for many of their own biochemical reactions; this cycle is vital to them. The process of incorporating carbon dioxide into the molecules of living matter is called fixation. Nearly all carbon dioxide fixation is accomplished by means of photosynthesisphotosynthesis
, process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the presence of chlorophyll. Some of the plants that lack chlorophyll, e.g.
..... Click the link for more information. , in which green plants form carbohydrates from carbon dioxide and water, using the energy of sunlight to drive the chemical reactions involved. Green plants use carbohydrates to build the other organic molecules that make up their cells, such as cellulose, fats, proteins, and nucleic acids. Some of these compounds require the incorporation of nitrogen (see nitrogen cyclenitrogen cycle,
the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification. Nitrogen is vital to all living matter, both plant and animal; it is an essential constituent of amino acids,
..... Click the link for more information. ). When carbohydrates are oxidized in cells they release the energy stored in their chemical bonds, and some of that energy is also used by the cell to drive other reactions. In the process of oxidation, or respiration, oxygen from the atmosphere (or from water) is combined with portions of the carbohydrate molecule, producing carbon dioxide and water, the compounds from which the carbohydrates were originally formed. However, not all of the carbon atoms incorporated by the plant can be returned to the atmosphere by its own respiration; some remain fixed in the organic materials that make up its cells. When the plant dies, its tissues are consumed by bacteria and other microorganisms, a process called decay. These microorganisms break down the organic molecules of the plant and use them for their own cell-building and energy needs; by their respiration more of the carbon is returned to the atmosphere. The carbon-containing molecules that an animal derives from consuming other organisms are reorganized to build its own cells or oxidized for energy by respiration, releasing carbon dioxide and water. When the animal dies it too is decayed by microorganisms, resulting in the return of more carbon to the atmosphere. Carbon-containing molecules in wood (or other dry, slow-decaying organic materials) may be oxidized by burning, or combustion, also producing carbon dioxide and water. Under conditions prevailing on earth at certain times, green plants have decayed only partially and have been transformed into fossil fuels—coal, peat, and oil. These materials are made of organic compounds formed by the plants; when burned, they too restore carbon dioxide to the atmosphere.

carbon cycle

(Bethe–Weizsächer cycle) A chain of nuclear fusion reactions by which energy may be generated in stars. The overall effect of the cycle is the transformation of hydrogen nuclei into helium nuclei with emission of gamma-ray photons (γ), positrons (e⁺), and neutrinos (ν). The major sequence of reactions is as follows: ¹²C + ¹H → ¹³N + γ ¹³N → ¹³C + e⁺ + ν ¹H + ¹³C → ¹⁴N + γ ¹H + ¹⁴N → ¹⁵O + γ ¹⁵O → ¹⁵N + e⁺ + ν ¹H + ¹⁵N → ¹²C + ⁴He

The carbon nucleus, ¹²C, reappears at the end of the cycle and can be regarded as a catalyst for the reaction: ¹H → ⁴He + 2e⁺ + 2ν + 3γ

Because nitrogen (N) and oxygen (O) intermediates are involved, the cycle is often termed the carbon-nitrogen-oxygen cycle or CNO cycle.

The carbon cycle is very strongly temperature dependent and becomes the dominant energy-producing mechanism at core temperatures exceeding about 20 million K. It is therefore thought to be the major source of energy in hot massive stars of spectral types O, B, and A. The carbon cycle was proposed by Hans Bethe and independently by Carl von Weizsächer in 1938. See also proton-proton chain reaction.

carbon cycle

[′kär·bən ‚sī·kəl] (geochemistry) The cycle of carbon in the biosphere, in which plants convert carbon dioxide to organic compounds that are consumed by plants and animals, and the carbon is returned to the biosphere in the form of inorganic compounds by processes of respiration and decay. (nuclear physics) carbon-nitrogen cycle

carbon cycle

carbon cycle

carbon cycle

car′bon cy`cle

carbon cycle

carbon cycle

carbon cycle,

carbon cycle

carbon cycle

carbon cycle

car·bon di·ox·ide cy·cle

carbon cycle

carbon cycle

car·bon di·ox·ide cy·cle

carbon cycle

carbon cycle

carbon cycle

Words related to carbon cycle

noun the organic circulation of carbon from the atmosphere into organisms and back again

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noun a thermonuclear reaction in the interior of stars

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