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Oxygen cycle refers to the movement of oxygen through the atmosphere (air), biosphere (plants and animals) and the lithosphere (the Earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different ...
Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the sources of carbon can be of organic or inorganic origin. [ 1] The terms aerobic respiration ...
An isotopic signature (also isotopic fingerprint) is a ratio of non-radiogenic ' stable isotopes ', stable radiogenic isotopes, or unstable radioactive isotopes of particular elements in an investigated material. The ratios of isotopes in a sample material are measured by isotope-ratio mass spectrometry against an isotopic reference material.
A heterotroph ( / ˈhɛtərəˌtroʊf, - ˌtrɒf /; [ 1][ 2] from Ancient Greek ἕτερος (héteros) 'other' and τροφή (trophḗ) 'nutrition') is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary ...
Oxygen began building up in the atmosphere at approximately 1.85 Ga. At current rates of primary production, today's concentration of oxygen could be produced by photosynthetic organisms in 2,000 years. [ 4] In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 ...
Oxygen radical absorbance capacity ( ORAC) was a method of measuring antioxidant capacities in biological samples in vitro. [1] [2] Because no physiological proof in vivo existed in support of the free-radical theory or that ORAC provided information relevant to biological antioxidant potential, it was withdrawn in 2012. [3] [4]
The tables below include tabular lists for selected basic foods, compiled from United States Dept. of Agriculture ( USDA) sources. Included for each food is its weight in grams, its calories, and (also in grams,) the amount of protein, carbohydrates, dietary fiber, fat, and saturated fat. [ 1] As foods vary by brands and stores, the figures ...
Scientists have discovered a new source of oxygen on the planet, originating from metal “batteries” deep beneath the Pacific Ocean. The “dark oxygen” phenomenon was observed at depths of ...