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Question 1
A student is studying the human digestive system and the role of enzymes in digestion. |
a) | Explain how enzymes, such as amylase, proteases, and lipases, contribute to the digestion process.
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b) | 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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c) | 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 2
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 3
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 4
There are numerous digestive substances that help break down food into smaller molecules that can be absorbed into the bloodstream. |
a) | What do we call substances like amylase and protease which speed up chemical reactions?
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b) | Describe how carbohydrates are digested.
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c) | 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 5
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 6
Adults should consume around 1 gram of protein per kilogram of body mass. Examples of foods that contain protein are meat, fish, eggs, nuts, and cheese. |
a) | Describe how you would test a sample of food to show it contains protein. Describe at least one safety precaution you would take during this test.
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Question 7
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) | Describe how the student can use a calorimeter to find the energy content of 10 g of bread.
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