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. A provitamin is similar in structure to a specific vitamin and can be converted to it by a few metabolic reactions. Antivitamins are compounds that prevent the normal function of certain vitamins. Antivitamins may act by binding a vitamin, by destroying a vitamin, or by inhibiting the coenzyme function of a vitamin.

(Encyclopedia Britannica)

Задание 2. Переведите предложения. Определите, являются ли данные утверждения

a) истинными,

b) ложными,

c) в тексте нет информации.

Подтвердите это цитатой из текста.

1. Vitamin and its provitamin are similar in chemical structure.

2. The term vitamin was originated from the word meaning “important for life”.

3. Vitamin C participates in some enzyme-catalysed reactions.

4. Vitamins are synthesised by a man in sufficient amount.

 

Задание 3. Переведите предложение. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

Vitamins are different in their structures.

Vitamins can be destroyed by some compounds.

 

Задание 4. Определите основную идею текста, ваш ответ переведите.

1. There exist water-soluble and fat-soluble vitamins.

2. Not all vitamins are amines.

3. Being essential for human health vitamins should be obtainable from the diet and other sources.

4. Antivitamins prevent normal functions of vitamins and destroy them.

 

Задание 5. А) Ответьте на вопрос:

Why is vitamin C treated as a vitamin?

Б) Выскажите свою точку зрения по вопросу:

Is it necessary to take vitamins?

 

Текст 3

Задание 1. Прочитайте и письменно переведите текст.

MINERAL DEPOSITS

1. Scientific discipline concerned with the distribution of mineral deposits, the economic considerations involved in their recovery, and assessment of the reserves available is called economic geology. Economic geology deals with metal ores, fossil fuels, and other materials of commercial value, such as salt, gypsum, and building stone. Minerals that make up the rocks are defined as inorganic substances which occur naturally and have a definite chemical composition and physical properties which vary within known limits.

2. The major properties which are used for identification purposes are: colour; crystal form, where available, although most minerals do not show well-developed crystals; cleavage which is the property of minerals to split along one or more series of parallel planes; specific gravity; hardness which refers to the ability of minerals to scratch or to be scratched; lustre which is described in such terms as metallic, glassy, etc. Of these diagnostic properties, colour is, perhaps, the least useful. Cleavage, on the other hand, is one of the most diagnostically useful mineralogical properties that are repeated throughout the mineral.

3. Minerals of use to man can be grouped into two broad categories according to their physical characteristics: metals, such as aluminium, copper, gold, silver, iron, tin, platinum, chromium, nickel, lead, zinc and non-metals such as diamonds, salt, limestone, cement, sulphur, and asbestos. When minerals occur so that they can be worked as a profit they are called ore deposits.

4. Economic minerals are those which are of economic importance and include both metallic (ore minerals) and non-metallic, as cryolite and sulphur. The principal reasons for distinguishing non-metallic deposits from metallic are practical ones and include such economic considerations as methods of recovery and uses.

 

Задание 2. Переведите предложения. Определите, являются ли данные утверждения

a) истинными,

b) ложными,

c) в тексте нет информации.

Подтвердите это цитатой из текста.

1. Inorganic substances have a definite chemical composition.

2. There are lots of categories in which minerals can be grouped.

3. Economic minerals include both metals and non-metals.

4. Some mineral deposits are considered to be formed by the activity of organisms.

 

Задание 3. Переведите предложение. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

1. Different diagnostic properties are used to identify minerals.

2. Economic geology is a scientific discipline dealing with commercial materials.

 

Задание 4. Определите основную идею текста, ваш ответ переведите.

1. Cleavage as one of the most useful mineralogical properties.

2. The usage of the deposits for the profit of people.

3. General information about mineral deposits.

4. The difficulty of distinguishing different types of minerals.

 

Задание 5. А. Ответьте на вопрос. Выберите вариант ответа, ответ переведите.

What is the least useful feature in identification purposes?

1. Luster, which is described in such terms as metallic, glassy etc.

2. Colour, which is used in diagnostic properties as well.

3. Cleavage, which is the property of minerals to split along one or more series of parallel planes.

4. Hardness, which refers to the ability of minerals to scratch or to be scratched.

Б. Выскажите свою точку зрения по вопросу:

What mineral deposits are important for the economy of Russia?

 

 

Текст 4

Задание 1. Прочитайте и письменно переведите текст.

COMPOSITE MATERIALS

1. Among the oldest and newest of structural materials are composite materials. It was discovered many years ago that two or more materials could be used together as one. Later it was proved that such a combination often behaved better than each material alone. Following this principle, clay and straw were combined to make bricks. For centuries composite materials remained virtually untapped. Only then monolithic materials, such as iron, copper were served for needs of an advancing technology. Recently it was a development of technology with coming of reinforced concrete, linoleum, plasterboard and plywood panels.

2. During the 1930`s and 1940`s light-weight honeycomb structures, machine parts made from compressed metal powders and plastic reinforced with glass fibers became commercial realities. These developments marked the beginning of the modern era of composite engineering materials. It was mentioned growing and using composite materials. The consumption of the fiber reinforced plastics, for example, has been increasing at the phenomenal rate of 25 per cent annually. Nevertheless, the emergence of a strict discipline and technology of composite materials is barely 20 years old.

3. There are two major reasons for the current interest in composite materials. The first is the demand for materials that will outperform the traditional monolithic materials. The second and more important in the long run, is that composites offer engineers the opportunity to design totally new materials, with the precise combination of properties needed for a specific task. Although new composites are usually more costly than conventional materials, they can be used more sparingly, because of their superior qualities.

 

Задание 2. Переведите предложения. Определите, являются ли данные утверждения

a) истинными,

b) ложными,

c) в тексте нет информации.

Подтвердите это цитатой из текста.

1. Composite materials cannot be used sparingly.

2. Light-weight honeycomb structures were invented in the 21st century.

3. The combination of materials works better than each of them alone. +

4. Composite materials are among the newest of structural materials.

 

Задание 3. Завершите утверждение согласно содержанию текста. Переведите ваш ответ.

Engineers insist on using composite materials despite their high cost because …

1) the interest in composite materials in constantly growing.

2) the usage of composite materials is commercially successful.

3) they use composite materials in advanced technologies.

4) by means of combination they can create new materials with necessary characteristics.

 

Задание 4. Определите основную идею текста, ваш ответ переведите.

1. In spite of their cost composite materials can be used more sparingly because of their advanced characteristics.

2. The development of light-weight honeycomb structures was the beginning of the modern era of composite engineering materials.

3. Composites are in demand in many spheres of industry due to their superior qualities which outperform traditional monolithic materials.

4. Composite materials such as bricks can be considered among the oldest and newest structural materials.

 

Задание 5. А. Ответьте на вопрос. Выберите вариант ответа, ответ переведите.

What are characteristics of composite materials?

Б. Выскажите свою точку зрения по вопросу:

Are composite materials environmentally friendly? What materials would you prefer for constructing your house?

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