BIOLOGY- BALANCED DIET- TNPSC,TET,RRB,SSC SCIENCE STUDYMATERIAL

BIOLOGY- BALANCED DIET- TNPSC,TET,RRB,SSC SCIENCE STUDYMATERIAL 

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.

            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).  

Incase 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  :

cereals (wheat, rice and maize), sugarcane,milk (contains lactose-a type of sugar) ,fruits honey, beet, etc.

Monosaccharide’s: 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)

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

FATS

             Provides twice the energy of carbohydrates

Acts as the reserve food material because excess fat is stored in the liver and as adipose tissue.

 Stored fat is used as fuel when glucose is not available.

An enzyme called Lipase digests fats. It breaks down into fatty acids and glycerol.

Our diet should contain less saturated fats.Excess of saturated fats increases the blood cholesterol level and may cause arteriosclerosis

Hydrogenation: Process by which unsaturated fatty acids are converted into saturated fatty acids by the addition of hydrogen.

Requirement : 50 gms daily.

Note: In whales and seals, the fat of the skin forms a thick layer called blubber.

PROTEINS

 Made up of Carbon, Hydrogen, Oxygen,Nitrogen and sometimes Sulphur.  Important for growth and repair of the body (75% of our body is proteins only)

Made up of amino acids.

Proteins are first broken into amino acids and then digested.

As Enzymes:As catalyst in digestion (Eg –Pepsin, Trypsin)

As a Hormone:To regulate body functions

In transport of different substances :(Eg- Haemoglobin- Transports O2 in blood, Myoglobin – Stores O2 in muscles)

As contractile proteins for contraction in muscles: (Eg Actin and Myosin)

Structural proteins: (Eg- Collagen Component of connective tissue, cartilage Keratin- Component of skin)

Protective proteins:(Eg. Gamma globulins)

Visual proteins: Rhodopsin and Iodopsin of rods and cones are proteins only.

(Rods and Cones are the cells which are present in Retina of the eye).

About 70-100 gms of proteins are daily needed.

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sources: Groundnuts, soyabean, pulses, lean meat, fish, eggs, milk, etc.

PROTEIN ENERGY MALNUTRITION

            In the age-group of 1-5 years.       

Kwashiorkar – Due to the deficiency of protein.When mother stops breast feeding.anaemia- In infants under 1 year of age.

Marasmus- Deficiency of proteins, carbohydrates and fats. between 6 months and 3 years.

MINERALS    

Apart from organic chemicals such as C, H,O, N human body needs inorganic chemical elements, called minerals,    for a wide range of functions. These elements are present in the form of ions       

Minerals help maintain the volume of water necessary to life processes in the body

Macroelements (more than 1 gm)

Microelements (less than 1 gm)

Deficiency of any of these leads to metabolic disorders.

VITAMINS

            Discovered by Funk

            Do not provide energy but help in different physiological processes.

            Vitamins are of 2 types: Water soluble, Fat Soluble

IMPORTANT VITAMINS REQUIRED IN HUMAN BEINGS

            B1 (Thiamine) – Beri-beri

            B2 or G (Riboflavin) – Cheilosis

            B3 or PP3 (Nicotinic acid or Niacin) – Pellagra

            B6 (Pyridoxine) – Dermatitis, anaemia

            B5 (Pantothenic acid) – Dermatitis

            Vit.H (Biotin) – Folic aic group – Megaloblasticanaemia

(low Hb content)

            B12 (Cyanocobalamine) – Pernicious anaemia

            Vit. C (Ascorbic acid) – Scurvy

FAT-SOLUBLE VITAMINS

Vit.A(Retinol) – Xerophthalmia due to non function of lacrimal gland of conjunctiva. night-blindness

Vit.D (Ergocalciferol and Cholecalciferol) – Rickets, Osteomalacia

Vit E (Tocopherol) – Reversible sterility

Vit K (Phylloquinone) – Haemorrhages

WATER

Important in digestion, transportation,excretion and to regulate body temperature (body contains 65% water)

ROUGHAGE

Fibrous material present in the cell wall of plants.

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Mainly contains cellulose.

It does not provide energy but only helps in retaining water in the body

Note:  

Excessive intake of food calories leads to obesity. It leads to high B.P. and heart problems and the person gets prone to diabetes, hypertension and other disorder.

Excessive intake of saturated fats like butter,ghee, etc, leads to hypercholesterolemia.

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