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45820593 form-2-science-chapter-2-part-1 (1)


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45820593 form-2-science-chapter-2-part-1 (1)

  1. 1. Form 2 scienceChapter 2 (part 1) Nutrition
  2. 2. 2.1 Classes of Food
  3. 3. Why nutrition is important ?• All living things need energy to continue their life processes .• This energy comes from the food we eat.• Food is also needed for growing and repairing worn-out body cells.• Energy is released from food by the process of respiration. CarbonFood oxygen Energy Water dioxide
  4. 4. The food can be classified into seven classes: Carbohydrate Vitamins
  5. 5. Carbohydrate• Sources: Rice, potatoes, bread, flour• Functions: To provide energy
  6. 6. Proteins• Sources: fish, eggs, milk, beans• Functions: - For growth and the repair of worn- out cells. - Prevent Kwashiorkor.
  7. 7. Fats• Sources: Cheese, butter, cooking oil, margarine• Functions: To provide twice as much heat energy as carbohydrates and to insulate the body against heat loss.
  8. 8. Vitamins• Sources: Fruits, vegetables• Functions: to maintain health and to prevent various deficiency of disease.
  9. 9. Minerals• Minerals are needed for normal growth and development of the body. They are needed in small quantities.• Sources: For eggs, milk, fish
  10. 10. Fibre or roughage • Sources: Vegetables, fruits, cereals • Functions: To prevent constipation and to help in peristalsis.Constipation = sembelit 便秘
  11. 11. Water• Sources: Water, fruits, beverages• Functions: To maintain the liquid condition of the cells and medium of various chemical reactions.
  12. 12. Facts About Vitamins Water •Vitamin B soluble •Vitamin CVitamins •Vitamin A Fat •Vitamin D soluble •Vitamin E •Vitamin K
  13. 13. • Functions: Promotes good night vision, maintains healthy skin.• Effect of deficiency: Night blindness, dry scaly skin
  14. 14. • Functions: Maintains healthy skin and nervous system.• Effect of deficiency: Beriberi, pellagra
  15. 15. • Functions: Maintain healthy skin. It also promotes wound healing.• Effect of deficiency: Scurvy, difficulty in healing wounds.
  16. 16. • Functions: Helps the body absorb calcium and phosphorus.• Effect of deficiency: Rickets
  17. 17. • Functions: i) Helps in formation of red blood cells and helps the body use vitamin K. ii) Improve male fertility.• Effect of deficiency: Sterility Sterility = Kemandulan 不育症
  18. 18. • Functions: Promotes blood clotting• Effect of deficiency: Blood unable to clot.
  19. 19. Calcium• Sources: Cheese, milk, eggs• Functions: Calcium helps form and maintain healthy teeth and bones. Helps blood clotting and construction of muscles.• Effects of deficiency: Rickets, osteoporosis
  20. 20. Sodium• Sources: Common salt, salted eggs, soy sauce…• Functions: Regulate blood pressure , maintains the function of muscles and nerves.• Effects of deficiency: Muscular cramps
  21. 21. Iron• Sources: Liver, eggs, spinach, lean red meat, salmon…• Functions: Formation of haemoglobin.• Effects of deficiency: Anaemia Anaemia = anemia 贫血
  22. 22. Iodine• Sources: seafood, leafy vegetables• Functions: Synthesis of thyroxine ( hormone that increases the rate of cell metabolism and regulates growth)• Effects of deficiency: Goitre
  23. 23. Phosphorus• Sources: Milk, cheese, eggs, meat, vegetable…• Functions: Formation of bones and teeth.• Effects of deficiency Rickets
  24. 24. Potassium• Sources: meat, nuts, bananas…• Functions: Maintain body fluid, proper function of nerves, regulation of heartbeat.• Effects of deficiency: Weak muscles, paralysisParalysis is loss of muscle function for one or more muscles.
  25. 25. Food tests1.Test For Starch2.Test for Glucose3.Test for protein4.Test for fats
  26. 26. Test for starch(a) Add a few drops of iodine solution to a test tube containing 3 ml of starch solution.(b) The starch solution turns dark blue in colour.
  27. 27. Test for glucose(a) Add about 1 ml of Benedicts solution to a test tube containing 3 ml of glucose solution.(b) Heat the mixture in the test tube using a water bath.(c) A brick-red precipitate is formed.
  28. 28. Test for proteins(a) Add a few drops of Millons reagent to a test tube containing 3 ml of albumen solution. (Albumen contains proteins)(b) Heat the mixture in the test tube using a water bath.(c) A red precipitate is formed.
  29. 29. Test for fats• Pour about 20 mm (depth) ethanol in to test tube• Add one drop of vegetable oil, and shake the tube sideways until the oil dissolves in the alcohol.• Add 2ml of water in the test tube.