life History on the Earth as well as the history of the Earth, begins with the Sun. Only recently the person has managed to seize the energy allocated at interactions of nuclear kernels. Short of it a unique energy source almost for all forms of a life is the Sun. Any energy source is necessary for work for any car: in hours energy of the compressed spring is used; on hydroelectric power station - kinetic energy of falling water; in the car working on gasoline, - chemical energy of molecules of the fuel, liberated in the course of their oxidation. Energy and to all live beings is necessary; they also take it from oxidised ' fuel ', named in this case food.

Food substances by the chemical nature are very various, but about their properties we can receive a certain general idea, having considered usual foodstuff - simple sugar glucose (С6 Н12 О6) which molecule includes 6 atoms of carbon, 12 atoms of hydrogen and 6 atoms of oxygen. All sugar belong to a class of carbohydrates - the chemical substances named so because in their molecule there is a carbon, and hydrogen with oxygen enter into it in the same parity (2: 1), as in a water molecule. glucose is formed (with simultaneous allocation of gaseous oxygen) in the reactions of photosynthesis proceeding in a green cage, of two simple substances - carbon and water dioxides. These reactions thanks to energy of the Sun (fig. 1.1) are carried out. The energy reserved in molecules of synthesised glucose, can be liberated in the course of breath, at which glucose; is oxidised to carbon and water dioxide. Breath, thus, represents chemical process, return to photosynthesis.

When the green plant grows, it catches and reserves a solar energy. Eating green plants or meat of animals which eat green plants, the person also depends on the Sun though and it is not so direct. Even the cars working on gasoline, and thermal power stations in which fire chambers coal is burnt, consume ' fossil ' a solar energy, i.e. The energy caught in the course of photosynthesis by organisms, living millions years ago.

There will be no the green plants which are carrying out a role of converters of a solar energy, almost all life on the Earth would stop. An exception would make unless some bacteria extracting energy necessary for them by oxidation of any unusual substrata, for example zakisi gland. However even these organisms depend on a solar energy at fixing of carbon which is necessary for them for construction of own body. however, they in any case make only insignificant part of all live beings occupying our Earth.

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