Прочитайте текст и ответьте на вопрос: What are vitamins essential for The vitamins as a class are n...: ответ на тест 911573 - Английский язык

                                   Текст I
               VITAMINS AND PROVITAMINS
(1) Vitamin is any of several organic substances that usually are separated into water-soluble and fat-soluble groups. The substances commonly known as vitamins are diverse in chemical structure and function. Originally defined as organic compounds obtainable in a normal diet and capable of maintaining life, vitamins are distinct from carbohydrates, fats, and proteins in function, as well as in the quantities in which organisms require them. If a vitamin is absent from the diet, a specific deficiency disease may develop.
(2) The term “vitamin” originated from “vitamine,” a word first used in 1911 to designate a group of compounds considered vital for life; each was thought to have a nitrogen-containing component known as an amine. The final e of vitamine was dropped when it was discovered that not all of the vitamins contain nitrogen, and, therefore, not all are amines. The term “accessory food factor” sometimes is used instead of vitamin to refer to these substances.
(3) Since they generally cannot be synthesized by an animal and must be obtained from the diet or from some synthetic source, vitamins are called essential nutrients. Vitamin C can be synthesized by some organisms in sufficient amounts so that the dietary requirement is eliminated; vitamin C usually is considered a vitamin, however, because it must be included in the diet of man. Vitamins are distinct from many other compounds, which, although indispensable for proper animal functions, can be synthesized in adequate quantities.
(4) Provitamin is similar in structure to a specific vitamin and can be converted to it by a few metabolic reactions. Antivitamin is a compound that prevents the normal function of certain vitamins. Antivitamin may act by binding a vitamin, by destroying a vitamin, or by inhibiting the coenzyme function of a vitamin.
                                                  (Encyclopedia Britannica)
Укажите главный смысловой компонент в составе нижеследующего сочетания слов:
     ... water-soluble and fat-soluble groups ... .

Укажите главный смысловой компонент в составе нижеследующего сочетания слов:
     ... water-soluble and fat-soluble groups ... .

                                                                  Текст I
                                          VITAMINS AND PROVITAMINS
 (1) Vitamin is any of several organic substances that usually are separated into water-soluble and fat-soluble groups. The substances commonly known as vitamins are diverse in chemical structure and function. Originally defined as organic compounds obtainable in a normal diet and capable of maintaining life, vitamins are distinct from carbohydrates, fats, and proteins in function, as well as in the quantities in which organisms require them. If a vitamin is absent from the diet, a specific deficiency disease may develop.
(2) The term “vitamin” originated from “vitamine,” a word first used in 1911 to designate a group of compounds considered vital for life; each was thought to have a nitrogen-containing component known as an amine. The final e of vitamine was dropped when it was discovered that not all of the vitamins contain nitrogen, and, therefore, not all are amines. The term “accessory food factor” sometimes is used instead of vitamin to refer to these substances.
(3) Since they generally cannot be synthesized by an animal and must be obtained from the diet or from some synthetic source, vitamins are called essential nutrients. Vitamin C can be synthesized by some organisms in sufficient amounts so that the dietary requirement is eliminated; vitamin C usually is considered a vitamin, however, because it must be included in the diet of man. Vitamins are distinct from many other compounds, which, although indispensable for proper animal functions, can be synthesized in adequate quantities.
(4) Provitamin is similar in structure to a specific vitamin and can be converted to it by a few metabolic reactions. Antivitamin is a compound that prevents the normal function of certain vitamins. Antivitamin may act by binding a vitamin, by destroying a vitamin, or by inhibiting the coenzyme function of a vitamin.
                                                                                                      (Encyclopedia Britannica)

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Where is the source of all vitamin A in?
Vitamin A is an unsaturated cyclic alcohol. It is synthesezed by at least three separate processes.
It has been concentrated and isolated from the non-saponiflable to be present in fish oil, both in the free alcohol and in the ester form. The source of all vitamin A is in the carotenoid pigments, the yellow-coloured, compounds occurring in all chlorophyll-containing plants.
In pure form it is a pale yellow oil, soluble in fat solvents, having an ultra-violet absorption spectrum. The ester forms of the vitamin have been found to possess greater stability than the free alcohol.

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What are Vitamin B1, Vitamin B2, Vitamin B6, Vitamin B12, Vitamin С and other stated to belong to?
Vitamin B1, Vitamin B2, Vitamin B6, Vitamin B12, Vitamin С and other are stated to belong to the water-soluble vitamin class. Vitamin B2 (riboflavine) is built up from a ribose and isoalloxazine residue, the name riboflavine being derived from the sugar component and the intense yellow fluorescence of it’s agucous solution.

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What is vitamin C essential for?
Vitamin С (ascorbic acid) is essential for the normal functioning of living cell and is involved in many enzymatic reactions. It is required for the development of cartilage, teeth and bones, for wound healing and aiding the absorption of iron from the intestin. Gross deficiency causes scurvy.

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The National Health Service provides free treatment for residents of Belarus. Visitors may use the service if there are special agreements between their countries and Belarus. Otherwise they are expected to pay.
We have hundreds of doctors and paramedical workers including primary health workers, laboratory assistants and nurses. The fundamental principle of our health service is the preventation of diseases. Prophylaxis is a part of the state policy.