Question
Enzymes are necessary for many biological processes, such as the digestion of fat.
(a) (i) Explain why enzymes are necessary for biological processes.
(ii) Lipase, protease and amylase are enzymes secreted into the alimentary canal.
Name one organ that secretes each enzyme. Choose your answers from this list.
You can use each organ only once.
(b) A group of students investigated the digestion of fat in milk.
• They added an alkaline solution to the milk.
• They divided the milk into four test-tubes.
• They added lipase and bile salts to some of the test-tubes, as shown in Table 5.1.
They did this at the same time for each test-tube.
• They kept all test-tubes at 40 °C.
• After 5 minutes, they added Universal Indicator solution to each test-tube.
(i) Explain why test-tube D was included in the investigation.
(ii) Explain why the colour in test-tube A was orange.
(iii) Explain the results for test-tubes B and C.
Answer/Explanation
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Question
(a) Starch, glucose and fructose are carbohydrates. Fructose syrup is used as a
sweetening agent as an alternative to sucrose.
The flow chart in Figure shows how fructose is prepared from maize starch.
(i) Name enzyme 1.
(ii) State why it is necessary to adjust the pH before an enzyme is added to the
process.
(b) Maize grains contain protease enzymes. With reference to the processes shown in
Fig. 3.1, suggest why it is important that these enzymes do not contaminate the glucose syrup.
(c) The formation of fructose syrup from glucose syrup is carried out at a temperature of
60 °C.
Suggest an important property of enzyme 2 that allows it to be used at temperatures as
high as 60 °C.
(d) Enzyme 2 is found naturally in many bacteria. Enzymes for use in washing powders
are obtained from bacteria.
Describe how bacteria are used to produce enzymes for washing powders.
(e) Pectinase is an enzyme that breaks down compounds known as pectins. Cell walls of
fruits, such as apples and mangoes, contain pectins.
Explain the advantages of using pectinase in fruit juice production.
Answer/Explanation
Ans:
