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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: - PowerPoint PPT Presentation
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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.
Carbohydrates
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
Scurvy
Types of food
Type of food Source Function Protein Meat Fish Eggs Growth and Repair of cells Carbohydrates Sugar Bread Potato Rice Energy Fats Butter, Oil, Energy
Insulation Protection
Vitamins (A.B,C D) Wheat Fish Fruit and Veg Healthy Body Minerals (Iron, Calcium) Vegetables, Milk Healthy Body
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 PyramidThe 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 Fats1) 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
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