Photosynthesis Pho`to*syn"the*sis, n. (Plant Physiol.) The process of constructive metabolism by which carbohydrates are formed from water vapor and the carbon dioxide of the air in the chlorophyll-containing tissues of plants exposed to the action of light. It was formerly called {assimilation}, but this is now commonly used as in animal physiology. The details of the process are not yet clearly known. Baeyer's theory is that the carbon dioxide is reduced to carbon monoxide, which, uniting with the hydrogen of the water in the cell, produces formaldehyde, the latter forming various sugars through polymerization. Vines suggests that the carbohydrates are secretion products of the chloroplasts, derived from decomposition of previously formed proteids. The food substances are usually quickly translocated, those that accumulate being changed to starch, which appears in the cells almost simultaneously with the sugars. The chloroplasts perform photosynthesis only in light and within a certain range of temperature, varying according to climate. This is the only way in which a plant is able to organize carbohydrates. All plants without a chlorophyll apparatus, as the fungi, must be parasitic or saprophytic. -- {Pho`to*syn*thet"ic}, a. -- {Pho`to*syn*thet"ic*al*ly}, adv. [Webster 1913 Suppl.]

The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • photosynthetically — adverb see photosynthesis …   New Collegiate Dictionary

  • photosynthetically — See photosynthetic. * * * …   Universalium

  • photosynthetically — adverb By the use of photosynthesis See Also: photosynthetic …   Wiktionary

  • photosynthetically — adv. (Biology) via photosynthesis, by using sunlight to produce carbohydrates (esp. in plants) …   English contemporary dictionary

  • photosynthetically — pho·to·synthetically …   English syllables

  • photosynthetically — adverb see photosynthetic …   Useful english dictionary

  • Photosynthetically Active Radiation — Die Photosynthetically Active Radiation (kurz PAR oder PhAR) ist der Bereich im Spektrum der Sonnenstrahlung, der von photosynthetisch aktiven Lebewesen genutzt werden kann. Dieser Bereich (380 780 nm) deckt sich weitgehend mit dem Bereich der… …   Deutsch Wikipedia

  • Photosynthetically Active Photon Flux Density — Bei der Photosynthetically Active Photon Flux Density, kurz PFD oder PPFD, handelt es sich um die Photonenstromdichte im photosynthetisch aktiven Strahlungsspektrum der Sonne. Sie wird meist in µmol(Photonen)/m²s angegeben. Es ist vor allem eine… …   Deutsch Wikipedia

  • Photosynthetically active radiation — The expression Photosynthetically Active Radiation, often abbreviated PAR, designates the spectral range of solar light from 400 to 700 nanometers that is useful to terrestrial plants in the process of photosynthesis. This spectral region… …   Wikipedia

  • photosynthetically active radiation — Abbreviation: PAR The part of the radiant energy that is capturable by natural photosynthetic systems (approximately equivalent to the natural light spectrum of wavelengths 400 700nm) …   Glossary of Biotechnology

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