| 释义 |
photosynthesis Bot.|fəʊtəʊˈsɪnθɪsɪs|
[ad. G. photosynthese: see photo- 1 + synthesis.]
The process by which carbon dioxide is converted into organic matter in the presence of the chlorophyll of plants under the influence of light, which in all plants except some bacteria involves the production of oxygen from water; also, any photochemical synthesis of a chemical compound.
1898Botanisches Zentralblatt LXXVI. 258 It is not important whether photosyntax or photosynthesis, or some other word, finally comes into general use to describe the manufacture of carbohydrates by green tissues under the action of light. 1902Encycl. Brit. XXXI. 760/1 The course of photosynthesis has been with tolerable certainty found to lead to the construction of sugar. 1914S. E. Sheppard Photo-Chem. vii. 295 The photo-synthesis of phosgene (COCl2) from chlorine and carbon monoxide..has been studied by several observers. 1924Industr. & Engin. Chem. Oct. 1018/1 The optimum experimental conditions having been determined, it has been found possible to carry out the photosynthesis on a larger scale than in the test tube. 1927Proc. R. Soc. A. CXVI. 203 The photosynthesis of complex organic substances takes place when carbonic acid in the presence of a surface is exposed to ultra-violet light. 1932Fuller & Conard tr. Braun-Blanquet's Plant Sociol. v. 97 There is a limited amount of photosynthesis in the invisible infra-red and ultra-violet. 1952P. W. Richards Trop. Rain Forest vii. 180 Even at the low light intensities found in the shade of the Tropical Rain forest, a high carbon dioxide concentration would probably allow a rate of photosynthesis considerably higher than at normal concentration. 1957Times 11 Sept. 6/2 Recent studies using radiocarbon indicated that the yield of photosynthesis by the plankton of the oceans was at least equal to that of the land flora, and might be several times greater. 1958R. Y. Stanier et al. Gen. Microbiol. xi. 213 In bacterial photosyntheses, there is also a light-driven reduction of CO2 to cell material, but oxygen is never produced because water cannot serve as the ultimate hydrogen donor. Instead, the reduction of CO2 is coupled with the oxidation of externally supplied organic or inorganic hydrogen donors. 1964E. J. H. Corner Life of Plants iii. 38 There are chromoplast colours that work together with chlorophyll in photosynthesis. 1975H. Smith Photochrome & Photomorphogenesis ii. 15 Photosynthesis presents an excellent example of light and dark reactions acting sequentially.
Hence ˌphotosynˈthetic a., of, pertaining to, produced by, or involved in photosynthesis; photosynthetic quotient or photosynthetic ratio, the rate of evolution of oxygen by photosynthesizing tissue divided by its rate of consumption of carbon dioxide, or the reciprocal of this; ˌphotosynˈthetically adv.
1900A. J. Ewart tr. Pfeffer's Physiol. Plants I. vii. 293 The photosynthetic assimilation in the chloroplastid only provides the organic food, which in green and non-green plants, and in animals also, has the same function to perform. Ibid. 326 With the exception of carbon dioxide, no carbon compounds are known which can be photosynthetically assimilated. 1913W. F. Ganong Living Plant ii. 27 The photosynthetic sugar and starch which appear in lighted green leaves. 1926H. A. Spoehr Photosynthesis ii. 92 The photosynthetic quotient may yield some information relative to the first product formed in photosynthesis. 1931E. C. Miller Plant Physiol. viii. 431 The determination of the photosynthetic ratio is difficult, because the process of respiration is proceeding at the same time and in the opposite direction [to that of photosynthesis]. 1945E. I. Rabinowitch Photosynthesis I. iii. 31 The ‘photosynthetic quotient’, Qp : Qp = ΔO2/-Δ/CO2. (The term ‘photosynthetic quotient’ has been used by many authors..to designate the inverse ratio, -ΔCO2/ΔO2; this difference calls for care in the quotation of numerical results.) 1962Listener 3 May 768/2 Some scientists believe that free oxygen is entirely biological in origin and that it arose after the emergence of photosynthetic life. 1971Sci. Amer. Sept. 92/3 Plants reflect about 8 percent of photosynthetically active wavelengths. 1971I. Zelitch Photosynthesis v. 129 At the high O2 concentrations, Amaranthus leaves had a photosynthetic quotient of 0·50 and bean leaves 0·33. 1974A. Huxley Plant & Planet iii. 22 It was probably not the seaweeds that gave rise to land plants but, from their similar photosynthetic pigments and photosynthetic mechanism, the green algae. |