1. Прочитайте текст и разделите его на логические части.

2. Озаглавьте каждую из выделенных частей.

3. Перечислите на английском языке все факторы, влияющие на энергетические потребности организма человека.

No matter how quiet a person may be, his body is constantly at work. Certain processes and activities always go on as long as life continues. The blood must circulate and the heart must beat. Breathing must take place and elimination of body wastes must be carried on. All these require energy, which must be supplied by the food taken into the body. Carbohydrates, fats and proteins, when oxidized or burned in the body, give energy. However, protein is not widely recommended or used as a chief dietary source of energy. Foods classed as “protein-rich” should be the source of 10 to 15 per cent of the total energy requirement. Fats should furnish 20 to 30 per cent of the total energy. This amount is well utilized by the body and also provides the desired quality to the diet. The remaining 55 to 70 per cent of the energy requirement should be met by “carbohydrate-rich” foods, such as cereals, bread, potatoes, other vegetables and fruits and sugar.

The energy of fuel value of a food is measured in terms of calories. A calorie, indicated by cal., is the amount of heat required to raise the temperature of one kilogram of water by one decree Centigrade. A gram of carbohydrate has an energy or fuel value of four calories; a gram of fat nine calories; a gram of protein four calories. The daily requirement of a woman may range from 2,000 to 2,600 calories or more and the daily requirement of a man, from 2,500 to 3,700 calories or more.

The energy need depends chiefly upon the activity, age and size, but also upon climate and season. A tall person requires more calories than a short one of the same weight, engaging in similar activity. A cold climate tends to make the energy requirements higher than a warm one under similar conditions.

Text № 4 «VEGETABLE PROTEINS»

1. Прочитайте текст и выделите ту часть, где представлена классификация белков.

Plants can build up from nitrates and salts of ammonia complex nitrogenous substances called proteins. A typical protein is eggalbumin, the white of an egg. It is colourless, thick, sticky¹, fluid², soluble in water. When put into boiling water, it coagulates, i.e., it becomes a solid mass and is no longer soluble in water. If the white of an egg be exposed to the air, it decomposes into a great number of substances. If heated with dilute acid, it breaks down into ammonia carbon dioxide, and a number of complex substances. Proteins are built up principally from the five elements: carbon, hydrogen, oxygen, nitrogen and sulphur.

The proteins found in the vegetable kingdom can be divided into seven main classes. We shall consider here only the glutenins, the prolamins and the globulins. The glutenins to which class wheat glutenin belongs are proteins which are not soluble in neutral salt solutions or in alcohol.

The prolamins are proteins soluble in alcohol. They were once called gliadins. To this class belongs gliadin from wheat or rye, hordein from barley, and zein from maize. The globulins are proteins insoluble in water but soluble in solutions of common salt. They are almost all coagulated by heating their solutions. It has long been known that, if a ball of dough (made from flour and water) be washed out, a compact mass of rubber-like material is left. This is gluten³. On treating with alcohol, it can be separated into two substances – glutenin and gliadin.

1. sticky – вязкий

2. fluid – текучий

3. gluten - клейковина

Text № 5 «FROM THE HISTORY OF VITAMINS»