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.
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.
