BIOLOGY- BALANCED DIET- TNPSC,TET,RRB,SSC SCIENCE STUDYMATERIAL
THE COMPONENTS OF FOOD ARE : CARBOHYDRATES, FATS, PROTEINS, MINERALS, VITAMINS , WATER AND ROUGHAGE.
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)
During the process of digestion, all carbohydrates are broken down to monosaccharides.
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.
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.
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.
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.
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
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
Important in digestion, transportation,excretion and to regulate body temperature (body contains 65% water)
Fibrous material present in the cell wall of plants.
Mainly contains cellulose.
It does not provide energy but only helps in retaining water in the body
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.