Question
Fat is a necessary component of the human diet.
(a) State three ways in which the human body uses fat.
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The arrows in Fig. 1.1 show the pathway of fat in part of the alimentary canal.
(b) State the name of
(i) the enzyme secreted by the pancreas that digests fat
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(ii) the products of chemical digestion of fat
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(iii) the liquid that is produced by the liver and stored by organ P in Fig. 1.1
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(iv) organ P in Fig. 1.1.
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(d) Explain how the products of fat digestion are transported from Q to the rest of the body.
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One possible effect of too much fat in the diet is coronary heart disease.
(e) Describe how too much fat in the diet may cause coronary heart disease.
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(f) Describe and explain how coronary heart disease can be treated.
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Answer/Explanation
Ans:
Question
Fish are an important part of a balanced diet for many people.
(a) Fish are a good source of vitamin D.
State one effect of a diet that is deficient in vitamin D.
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(b) Many fish stocks have declined.
Marine ecologists considered the three topics shown in Fig. 6.1 when they discussed the
decline of fish stocks.
Describe the key points for each of the three topics shown in Fig. 6.1.
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Answer/Explanation
Ans:
Question
Fig. 7.1 shows the human alimentary canal and some of the organs associated with it.
(a) Use letters from Fig. 7.1 to identify which structure carries out a particular function. Write your answers in Table 7.1.
(b) Name the process which moves food from D to F.
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(c) A student investigated the digestion of fats by the enzyme lipase. He found that as lipase digested the fats, the pH of the solution changed from pH 8 to pH 6.
(i) Explain why the digestion of fats changed the pH of the solution.
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(ii) Fig. 7.2 shows three test-tubes that were set up for this experiment.
The time taken for the indicator to change colour after the lipase was added was measured. The results are shown in Table 7.2.
Explain why the indicator in test-tube B changes colour much faster than the indicator in test-tube A.
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(d) Some biological washing powders contain lipase. Instructions on the packet state that biological washing powders should be used in warm water but not in very hot water. Explain why warm water should be used instead of very hot water. Use Fig. 7.2 and Table 7.2 to help with your answer.
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(e) Eating too much fat can be harmful. State one way in which too much fat can be harmful to human health.
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Answer/Explanation
Ans:
(a) 
(b) peristalsis;
(c) (i) fat digestion produces fatty acids (and glycerol);
fatty acids lower pH;
(ii) (B contains bile) which emulsifies fats;
increases surface area for enzyme/ lipase action/AW;
(so) fatty acids are produced more quickly / more rapid fat digestion;
colour of indicator changes more quickly;
(d) hot water could denature the enzyme;
changes the shape of active site of enzyme/ enzyme
inactive;
tube C shows that boiled enzyme does not digest fats;
(e) obesity;
(which) leads to joint damage;
blockage of blood vessels / heart disease/CHD/atherosclerosis / cardiac arrest;
high blood pressure;
type 2 diabetes;
cancer;
AVP;