digestion I.doc

F.4 Biology Class Exercise- Digestion of food IName: _ F.4 ( ) Group: _Task 1 : 1.The following drinks and foods are rich in carbohydrates. ricelucozade banana(a)Name the main form of carbohydrate that is found in (i)Lucozade : _(ii)rice: _(iii)banana: _ ( 1 mark )(b)Select the food/ drink which you think is the most suitable for a tennis player(i)one day before a tennis match. (ii)during the break of a tennis match. Give a reason for your choice .(i)_(ii)_Task 2 :2.Digestion of different types of food substances takes place in different regions of the human alimentary canal. The graph below shows the extent to which proteins, starch and fats are being digested in successive regions, from A to E, of the alimentary canal. Z C stomach(a)Using the letters in the diagram ONLY, state ( 2 marks )(i)the type of food substance that is digested first.()(ii)the part where all the three types of food substances are digested.()(iii)the part(s) where proteins are digested.()(iv)the part where fat is digested.() (b)Write word equations to show the digestion of Y in part D. ( 3 marks )_(c)Why is food Z not digested in the mouth cavity ? ( 1 mark )_(d)Why is food X not digested in the stomach ? ( 1 mark )_(e)On the graph, add a line to show what will happen to cellulose. ( 1 mark )3.Many people suffer from an inherited condition known as “lactose intolerance”. The sufferers cannot digest and metabolize lactose, the sugar found in milk. The condition is caused by the inability to secrete the enzyme lactase in the digestive system. In normal people, lactose in milk will be digested to galactose and glucose.(a)Suggest a function of the enzyme lactase. ( 2 marks )_(b)Suggest a possible reason why people suffering from lactose intolerance cannot secrete lactase. ( 1 mark )_(c)For a lactose intolerance sufferer, what will happen to the lactose after he has taken milk or dairy products ?( 2 marks )_(d)The following symptoms are usually associated with lactose intolerance sufferers after they have taken milk or dairy products :Abdominal pain, bloating (腹脹 ) , diarrhea ( 腹瀉 )(i)Bloating is caused by the accumulation of gases. Where do these gases come from ? ( 2 marks )_(ii)Using your knowledge about peristalsis, suggest a possible cause of diarrhea under this condition. ( 2 marks )_* Hint : The large intestine contains a large population of