| red drop effect | Experimental observation that the photosynthetic efficiency of monochromatic light is greatly reduced above 680 nm, even though chlorophyll absorbs well up to 700 nm. Led to the discovery of the two light reactions of photosynthesis. See: photosystems I and II. (18 Nov 1997) |
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| gibbs-donnan effect | The observation that charged molecules starting on one side of a semipermeable membrane sometimes will not evenly distribute themselves by diffusion on both sides of the membrane. This effect is probably because there are other charged substances already present which cannot move through the membrane themselves and which are creating an electric field that influences the movement of the incoming charged molecules. (09 Oct 1997) |
| maternal effect gene | Gene, usually required for early embryonic development, whose product is secreted into the egg by the mother. The phenotype is thus determined by the mother's, rather than the egg's, genotype. Compare:. Zygotic effect gene. See: egg polarity gene. (18 Nov 1997) |
| Pasteur effect | <biochemistry> Decrease in the rate of carbohydrate breakdown that occurs in yeast and other cells when switched from anaerobic to aerobic conditions. Results from a relatively slow flux of material through the biochemical pathways of respiration compared with those of fermentation. (18 Nov 1997) |
| Pasteur's effect | The inhibition of fermentation by oxygen, first observed by Pasteur; either not observed, or only slightly observed, in malignant tumours. Compare: Crabtree effect. (05 Mar 2000) |
| glucose effect | <biochemistry> The ability of the sugar glucose to block sugar metabolism by keeping the genes which make the enzymes involved in the early steps of sugar metabolism from making those enzymes. (09 Oct 1997) |
| greenhouse effect | The effect of certain gases in the Earth's atmosphere in trapping heat from the sun. (05 Dec 1998) |
| Rivero-Carvallo effect | Inspiratory increase in the systolic murmur of tricuspid insufficiency; the characteristic distinguishing tricuspid insufficiency from mitral insufficiency. (05 Mar 2000) |
| Circe effect | An effect observed in enzyme catalysis in which accelerated diffusion of the substrate occurs through attractive forces of the enzyme's active site. (05 Mar 2000) |
| Russell effect | The ability of an agent, other than light, to make a developable latent image in a photographic film emulsion. Synonym: Russell effect. (05 Mar 2000) |
| clasp-knife effect | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
| photechic effect | The ability of an agent, other than light, to make a developable latent image in a photographic film emulsion. Synonym: Russell effect. (05 Mar 2000) |
| photoelectric effect | <chemistry, radiobiology> The interaction of a photon with an atom, resulting in the absorption of the incident photon and the release of a bound electron from that atom with energy equal to the photon energy less the electron binding energy. (16 Dec 1997) |
| mirror effect | <physics> A charged particle travelling into an increasing magnetic field will (if the field becomes strong enough) reverse direction and be reflected back. This is a direct result of the adiabatic invariance of the magnetic moment. Plasmas can be confined by devices which utilise this effect. The effect also occurs in some toroidal plasmas, since the toroidal magnetic field is stronger on the inboard side than on the outboard side, in this case it gives rise to so-called neoclassical effects. The strength of the mirror is determined by the mirror ratio. (09 Oct 1997) |
| piezoelectric effect | The property of certain crystalline or ceramic materials to emit electricity when deformed and to deform when an electric current is passed across them, a mechanism of interconverting electrical and acoustic energy; an ultrasound transducer sends and receives acoustic energy using this effect. (05 Mar 2000) |