Monday, 6 April 2020

TNPSC STUDY MATERIAL -ENGLISH MEDIUM - BIOLOGY - 1

BALANCED DIET

 The components of food are : Carbohydrates, Fats, Proteins, Minerals, Vitamins , Water and Roughage.

CARBOHYDRATES

 Constitutes 3 elements: Carbon, Hydrogen and Oxygen

 Carbohydrates form a better fuel than proteins and fats because their molecules have relatively more oxygen.

 Main source of energy providers.

 Glucose, often called blood sugar.

 An adult man of average weight and doing moderate work needs about 500 gms of carbohydrates daily. Growing child, nursing mother and sports-persons need more carbohydrates.

 Is of 3 types: Cellulose, Sugar and Starch.

 Cellulose is present in the cell-wall of plants. It cannot be digested and simply acts as roughage.

 D-fructose is the sweetest of sugars. It is found in fruit juices, honey etc.

 Excess sugar is stored as glycogen in liver (by a process called glycogenesis). The sugar which is still left is converted into fat and stored in various parts of the body a adipose tissue (by a process called lipogenesis). In case the food provides inadequate glucose, reserve glycogen is converted into glucose for use in energy production. This conversion is known as Glycogenolysis.

 Sources of Carbohydrates are : 3 main cereals (wheat, rice and maize), sugarcane, milk (contains lactose-a type of sugar) , fruits honey, beet, etc.

 Monosaccharides: They are the simplest carbohydrates and are made up of one unit only (eg. glucose, fructose, galactose).

 Disaccharides: 2 units of monosaccharides (eg. sucrose, lactose and maltose)

 Polysaccharides: Those carbohydrates which contain a no. of monosaccharide units. (eg: starch in plants and glycogen in animals)

 During the process of digestion, all carbohydrates are broken down to monosaccharides.

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