dark reaction

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Related to Light-independent reaction: Dark reactions

dark re·ac·tion

in photosynthesis, the fixation of CO2 into carbohydrate, which is independent in place and time of the absorption of light.

dark reaction

Any of the chemical reactions that take place as part of the second stage of photosynthesis and do not require light to occur, by which energy released from ATP drives the production of organic molecules from carbon dioxide.


1. opposite action or counteraction; the response of a part to stimulation.
2. the phenomena caused by the action of chemical agents; a chemical process in which one substance is transformed into another substance or substances.

chain reaction
one which is self-propagating; a chemical process in which each time a free radical is destroyed a new one is formed.
coupled reaction
one in which the free energy released by one chemical reaction drives the other reaction.
dark reaction
photosynthetic reaction which fixes CO2 into sugar and which occurs without exposure to light. Called also Calvin cycle.
reaction of degeneration
the reaction to electrical stimulation of muscles whose nerves have degenerated, consisting of loss of response to a faradic stimulation in a muscle, and to galvanic and faradic stimulation in the nerve.
delayed reaction
a reaction, such as an allergic reaction, occurring hours to days after exposure to an inducer.
false negative reaction
an erroneously negative reaction to a test.
false positive reaction
an erroneously positive reaction to a test.
first set reaction
immune reaction
1. immune response; see also immunity.
2. formation of a papule and areola without development of a vesicle following smallpox vaccination.
lengthening reaction
reflex elongation of extensor muscles that permits flexion of a limb.
leukemic reaction, leukemoid reaction
a peripheral blood picture resembling leukemia or indistinguishable from it on the basis of morphological appearance alone, characterized by immature leukocytes in the blood.
reaction pattern analysis
designed to replace archaic, non-specific descriptions of the reactions of the skin to noxious influences; recommended categories are (1) perivascular dermatitis, (2) interface dermatitis, (3) vasculitis, (4) nodular and diffuse dermatitis, (5) intradermal vesicular and pustular dermatitis, (6) subepidermal vesicular and pustular dermatitis, (7) perifolliculitis, folliculitis and furunculosis, (8) fibrosing dermatitis, (9) panniculitis, (10) atrophic dermatosis, (11) mixed reaction patterns.
second set reaction
reaction specificity
lack of production of by-products in enzymatic reactions with yields of products being nearly 100%.
Strauss reaction
development of suppurative peritonitis, localized to the scrotal sac, in the guinea pig after the intraperitoneal injection of material containing Burkholderia mallei.
stress reaction
1. alarm reaction.
2. gross stress reaction.
reaction time
the time elapsing between the application of a stimulus and the resulting reaction.
wheal-flare reaction
a cutaneous sensitivity rection to skin injury or administration of antigen, due to histamine production and marked by edematous elevation and erythematous flare.