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Question 1
Bread contains many types of biological molecules, including starch, protein and fat. |
a) | Amylase catalyses the digestion of into simple sugars. Protease catalyses the digestion of . The product of this reaction is . starch proteins amino acids
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b) | Different parts of the human digestive system help to break down molecules of fat so that they can be absorbed into the body. Describe how. To gain full marks you should refer to:
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Question 2
A student is studying the human digestive system and the role of enzymes in digestion. |
a) | Describe the function of the digestive system.
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b) | Explain how enzymes, such as amylase, proteases, and lipases, contribute to the digestion process.
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c) | A student carries out a practical activity to investigate the effect of pH on the rate of reaction of amylase enzyme. Describe how the student could set up this experiment.
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d) | The student finds that the rate of reaction decreases as the pH moves away from neutral. Explain why this might be the case.
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Question 3
A student is learning about the role of different enzymes in the human digestive system. |
a) | Name the enzyme that breaks down carbohydrates and the products of this breakdown.
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b) | Explain how the products of digestion are used by the body.
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c) | The graph shows the effect of pH on the activities of three digestive enzymes, A, B and C. Each enzyme is produced by a different part of the digestive system. |
c i) | What is the optimum pH for enzyme B?
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c ii) | Cells within the stomach lining secrete a substance that alters the pH of the stomach, making it the optimum pH for the activity of one of the enzymes in the graph. Name this substance.
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c iii) | Which enzyme, A, B or C, would work best in the human stomach?
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Question 4
A student is learning about the role of bile in the human digestive system. |
a) | Where is bile produced and where is it stored?
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b) | Label the organ where bile is produced with the letter X on the diagram.
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c) | Explain the role of bile in the digestion of fats.
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d) | The table shows the activity of lipase on fat in three different conditions. |
Explain, as fully as you can, the results shown in the table.
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Question 5
A student is studying the effect of temperature on enzyme activity in the human digestive system. |
a) | Describe how temperature affects enzyme activity.
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The student decided to investigate the digestion of fat by lipase. In the investigation:
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b) | State:
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c) | The pH of the solution in each tube was tested at the beginning of the experiment and after 24 hours. The results of are shown in the table. |
c i) | The student may not have found the best temperature for the lipase to work. What more could they do to find the best temperature?
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c ii) | Which two of the following substances are produced when lipase breaks down fats? A glycogen B glycerol C amino acids D fatty acids
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c iii) | Explain the results obtained by the student at 0, 40 and 80°C.
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Question 6
There are numerous digestive substances that help break down food into smaller molecules that can be absorbed into the bloodstream. |
a) | Complete the table to give one site where each digestive substance is made.
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b) | What do we call substances like amylase and protease which speed up chemical reactions?
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c) | Describe how carbohydrates are digested.
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d) | Describe how to use a test to determine if the breakdown of starch has taken place in a sample of food.
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Question 7
The table below shows the nutritional information of hot dogs made from pork and a plant-based alternative, made from soya. |
a) | Evaluate the use of hot dogs made from pork compared with the plant-based hot dogs in providing customers with a healthy, balanced diet. Use information from the table and your own knowledge to answer the question.
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Question 8
Adults should consume around 1 gram of protein per kilogram of body mass. Examples of foods that contain protein are meat, fish, eggs and cheese. |
a) | Describe, in as much detail as you can, what happens to protein in food after it is swallowed.
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b) | Describe how you would test a sample of food to show it contains protein. Describe at least one safety precautions you would take.
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Question 9
A student tested foods for different biological molecules. His results were recorded in the following table. |
a) | Suggest why the student recorded one of the results with a question mark.
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b) | Which of these statements are correct about the composition of cheese? A cheese contains starch B cheese contains protein C cheese contains fats D cheese contains sugars
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c) | The student is worried that the results for apple juice and vegetable oil have been swapped. Give two reasons why this is not possible.
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d) | How can the student test the apple juice to see if it contains vitamin C?
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Question 10
a) | Describe how the action of the mouth, oesophagus and stomach contributes towards the digestion of food.
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b) | The pH in the mouth decreases after eating a meal. Why do dentists recommend to brush teeth after eating? A acidic conditions help bacteria to grow. B acids dissolve tooth enamel. C alkaline conditions help bacteria to grow. D alkalis dissolve tooth enamel.
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