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Passion cycle

(Encyclopedia)Passion cycle, in art, the depiction of the last events in the life of Jesus. The Passion was a favorite subject of medieval and Renaissance artists and was considered the most ambitious of projects. ...

carbon cycle

(Encyclopedia)CE5 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 sim...

nitrogen cycle

(Encyclopedia)CE5 Nitrogen cycle nitrogen cycle, the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification. Nitrogen...

proton-proton cycle

(Encyclopedia)proton-proton cycle: see nucleosynthesis. ...

carbon-nitrogen-oxygen cycle

(Encyclopedia)carbon-nitrogen-oxygen cycle: see nucleosynthesis. ...

malic acid

(Encyclopedia)malic acid: see Krebs cycle.

succinic acid

(Encyclopedia)succinic acid: see Krebs cycle.

urea

(Encyclopedia)CE5 urea yo͝oēˈə [key], organic compound that is the principal end product of nitrogen metabolism in most mammals. Urea was the first animal metabolite to be isolated in crystalline form; its c...

Fischer, Edmond Henri

(Encyclopedia)Fischer, Edmond Henri, 1920–, American biochemist, b. Shanghai, China. As researchers at the Univ. of Washington in Seattle, Fischer and Edwin G. Krebs discovered a biological regulatory mechanism, ...

laetrile

(Encyclopedia)laetrile lāˈətrĭlˌ [key], name given to the chemical amygdalin, a substance derived from an extract of the kernels of many fruits, notably apricots, bitter almonds, and peaches. The idea that lae...