2. The processes of nutrition ingestion digestion absorption assimilation egestion

4. Teeth Structures external structure internal structure enamel dentine blood capillaries nerve fibres cement jaw bone gum crown neck root pulp cavity ( pulp tissues )

6. Teeth Structures - hard like bone but softer than enamel ,living tissue, thread of cytoplasm are running through it. It is hardened by vitamin D external structure internal structure dentine crown neck root

7. Teeth Structures - supply food & oxygen for growth & maintaining alive - produce sensation of pain when stimulated external structure internal structure crown neck root blood capillaries nerve fibres pulp cavity ( living tissues )

8. Teeth Structures made up of connective tissues which make up your dentine and keep tooth alive. external structure internal structure crown neck root blood capillaries nerve fibres pulp cavity ( living tissues )

10. Teeth Structures - fibres attaching tooth to jawbone external structure internal structure gum crown neck root jaw bone Periodontal membrane

12. Types of teeth Types of Teeth Shape Functions Incisor Chisel-like & sharp Biting & cutting food Canine Pointed, curved & long Killing prey & tearing flesh Premolar & Molar 2 blunted points of cusps Crushing & grinding food

16. Investigation 7.1 Effect of Acid on a Tooth

17. What do you find on the covered and uncovered parts of the tooth ? Ans: The acid dissolves the exposed enamel and leaves a small hole on the uncovered part, but holes do not appear on the covered part. tooth covered with wax dilute hydrochloric acid probing scraping

18. Does the acid take place in causing tooth decay ? Ans: Actually the acid produced by bacteria in the mouth is not very strong. Tooth decay is due to bad habits over a long period of time. tooth covered with wax dilute hydrochloric acid probing scraping

25. A process by which large food molecules are broken down into smaller pieces Digestion

26. Why is digestion needed?

27. Because: food pieces and their molecules (e.g. starch, protein & fat) are usually too large to pass through the wall of our body for absorption (Note: Simple sugars, water, vitamins & minerals are small enough to be absorbed immediately.)

29. Human Digestive System salivary glands epiglottis oesophagus diaphragm cardiac sphincter stomach spleen pyloric sphincter colon caecum rectum anus large intestine pancreas buccal cavity tongue tooth trachea liver duodenum ileum appendix small intestine gall bladder

30. Mechanical Digestion Chewing : break down food into smaller pieces by teeth to increase the surface area for enzyme action ( physical digestion )

31. Chemical Digestion Enzymatic Reactions which digest food into simpler chemical forms

32. Investigation 7.2 To show the Differential Permeability of Dialysis Tubing to Starch & Glucose

33. Why is it necessary to rinse the dialysis tubing with tap water ? Ans: In order to remove any starch and glucose that may remain on the outside of the dialysis tubing. Starch-glucose mixture thread Test for glucose Test for starch

34. Which food substance is present in water surrounding the dialysis tubing 30 minutes after the beginning of the experiment ? Explain your answer. Ans: Glucose. As dialysis tubing is selectively permeable, starch molecules are too large to pass through the holes in the tubing... Starch-glucose mixture thread Test for glucose Test for starch

35. Which food substance is present in water surrounding the dialysis tubing 30 minutes after the beginning of the experiment ? Explain your answer. Ans: Only glucose molecules are small enough to pass through the dialysis tubing in this experiment. Starch-glucose mixture thread Test for glucose Test for starch

36. Which part of the body is presented by the dialysis tubing and the water in the boiling tube respectively ? Ans: Ileum and blood are represented by the dialysis tubing and water respectively. Starch-glucose mixture thread Test for glucose Test for starch

37. Where is food digested?

38. Sites where digestion occurs: Alimentary canal (gut) 1. Buccal cavity 2. Stomach 3. Small intestine

39. How is food digested in these sites?

41. Investigation 7.3 Action of Amylase on Starch

42. What are the results of the iodine test and Benedict’s test for tube A ? Ans: The result of iodine test is negative while the result of the Benedict’s test is positive. A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

43. What are the results of the iodine test and Benedict’s test for tube B ? Ans: The result of iodine test is positive while the result of the Benedict’s test is negative. A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

44. What are the results of the iodine test and Benedict’s test for tube C ? Ans: The result of iodine test is positive while the result of the Benedict’s test is negative. A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

45. Why is the temperature of the water bath set at 37 ℃ ? Ans: Because enzymes work best at 37 ℃ . A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

46. What is the action of amylase on starch ? Ans: Amylase is an enzyme in saliva which helps to digest starch into maltose. A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

47. What is the effect of boiling on amylase ? Ans: Amylase denatured after boiling. A B C thermometer water bath at 37 ℃ after 30 minutes each test tube test with Benedict’s solution test sample with iodine solution

48. Chemical Digestion break down of starch molecules into maltose molecules by salivary amylase (from salivary glands) Starch maltoses salivary glands

49. Stomach (Physical Digestion) Stomach Entrance: Cardiac Sphincter Stomach Exit: Pyloric Sphincter Relaxation of cardiac sphincter & contraction of pyloric sphincter enable storage of food in stomach for a longer period of time

50. Stomach (Physical Digestion) Squeezing & churning actions of stomach break down the partly digested food into smaller pieces which forms a semi-fluid called Chyme

53. Small Intestine (mainly chemical digestion) Digestion of various food substances by several kinds of digestive juices Digestive juices found in small intestine: 1. Bile 2. Pancreatic juice 3. Intestinal juice

56. Bile - contain bile salts which emulsify lipids into smaller droplets without chemical change ( ∴ NOT digest fats) - provide alkaline medium for enzymes to work oil oil droplets

57. Investigation 7.4 Effect of Bile Salt on Fat

58. What happens to the mixtures in tubes A & B ? Ans: In tube A, bile salt emulsifies the vegetable oil to droplets. In tube B, the oil floats on top of water since oil and water do not mix well. 1cm 3 of vegetative oil shaking shaking observe observe 10 drops of bile salt solution A B

59. What is the action of bile salt on oil ? Ans: The bile salt reduces the surface tension of oil and emulsifies oil to droplets. 1cm 3 of vegetative oil shaking shaking observe observe 10 drops of bile salt solution A B

62. pancreatic amylase starch maltose starch maltose

63. pancreatic proteases protein Dipeptides/ polypeptides protein dipeptide protease

64. pancreatic lipases glycerol + 3 fatty acids lipid lipase glycerol fatty acids lipid

66. Intestinal Juice - Contain enzymes of 2 categories: 1. Carbohydrase (eg. maltase ) 2. Protease

67. disaccharides (eg. maltose) monosaccharides (eg. glucose ) intestinal carbohydrase carbohydrase disaccharide monosaccharide

68. intestinal proteases dipeptides amino acids protease amino acid

71. Structure of a Villus lacteal Epithelial cell arteriole venule blood capaillaries lymph vessel villi

72. Transverse Section of a villus showing food absorption glycerol nucleus fatty acid glucose amino acid fat capillary lacteal Micro-villus epithelial cell

76. Digestive System in Rabbit

77. Alimentary canal of a rat

82. ~ END ~