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Food. Chapter 3. Function of food. All living things need food. The functions of food are: 1) To provide energy 2) To provide material for growth and repair of cells 3) Protection against disease. Types of food. Carbohydrates:
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Food Chapter 3
Function of food • All living things need food. • The functions of food are: 1)To provide energy 2) To provide material for growth and repair of cells 3) Protection against disease
Types of food Carbohydrates: Sugars(fruits, cakes, jams and sweets) and starch(potatoes pasta and bread) provide energy. Fibre(whole-grain bread, vegetables and cereals) prevents constipation.
Fats Fats Fats(milk, fatty meat) store energy,insulate the body against heat loss and protect vital organs.
Protein Protein (meat, fish and eggs) are necessary for the growth and repair of cells.
Minerals and Vitamins Minerals Iron is necessary to make red blood cells. Calcium is necessary for healthy bones. Vitamins Vitamin C is necessary for healthy teeth and gums Vitamin D is necessary for strong bones
Types of food A balanced diet consists of the right amount of the six constituents, carbohydrates, protein, fats vitamins minerals and water to stay healthy
Food and energy The energy content of food is given in kilojoules (kj) The energy required from an average 14 year old is: Boy- 12,000 kj Girl- 10,000 kj Different foods provide us with different amounts of energy.
Food Pyramid The food pyramid shows roughly the amount of each common food types per day for the average child or adult for a healthy balanced diet.
Test for Starch 1)Add a few drops of Iodine to a test tube of Starch Result The Iodine turns blue black in colour
Test for Glucose 1)Add a few drops of Benedicts solution to a glucose solution. Result After heating the solution will turn a brick red colour
Test for Protein 1)Add some sodium hydroxide and a few drops of Copper Sulfate to a test tube containing milk. Result The solution will turn a purple/violet colour.
Test for Fats 1) Rub a piece of food onto some brown paper 2) Allow the paper to dry. Result: A translucent spot(allows light to pass through) is seen on the paper
To show the conversion of chemical energy to heat energy 1) Set up apparatus as shown in the diagram. 2) Record the temperature of the water. 3) Ignite the foods source and place it under the beaker of water. 4) After 1 minute remove the food and record the new temp of the water. Result As the food burned the chemical energy in the food was converted into heat energy.
Web sites http://www.primaryresources.co.uk/science/foodgroups.htm http://www.kelloggs-alarabi.com/english/teacher%20section/trail/foods.html# http://library.thinkquest.org/5777/dig1.htm http://kidshealth.org/kid/body/digest_noSW.html