Digestive System & Biological Molecules - exam practice
Digestive System & Biological Molecules
Question 1 of 6
A student is studying the human digestive system and the role of enzymes in digestion.
Explain how enzymes, such as amylase, proteases, and lipases, contribute to the digestion process.
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.
The student finds that the rate of reaction decreases as the pH moves away from neutral.
Explain why this might be the case.
A student is learning about the role of different enzymes in the human digestive system.
Name the enzyme that breaks down carbohydrates and the products of this breakdown.
Explain how the products of digestion are used by the body.
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.
What is the optimum pH for enzyme B?
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.
Which enzyme, A, B or C, would work best in the human stomach?
A student is studying the effect of temperature on enzyme activity in the human digestive system.
Describe how temperature affects enzyme activity.
The student decided to investigate the digestion of fat by lipase.
In the investigation:
- The student set up five test tubes.
- Each tube contained 1 cm3 of fat and 5 cm3 of lipase solution.
- Each tube was kept at a different temperature for 24 hours.
State:
- one control variable in this investigation
- the independent variable being investigated
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.
The student may not have found the best temperature for the lipase to work.
What more could they do to find the best temperature?
Which two of the following substances are produced when lipase breaks down fats?
Explain the results obtained by the student at 0, 40 and 80°C.
There are numerous digestive substances that help break down food into smaller molecules that can be absorbed into the bloodstream.
What do we call substances like amylase and protease which speed up chemical reactions?
Describe how carbohydrates are digested.
Describe how to use a test to determine if the breakdown of starch has taken place in a sample of food.
The table below shows the nutritional information of hot dogs made from pork and a plant-based alternative, made from soya.
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.
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.
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.