1. 1
   An office worker who has relied on fast-food meals for lunch every day for several months complains to a dietician of frequent constipation and low energy. The dietician reviews his diet and finds it is high in fat and refined carbohydrate but very low in fibre and water, with almost no fruit, vegetables or wholegrain foods.

   (a)

   What is dietary fibre mainly needed for?

   [1 mark]

   • AProviding energy for respiration
   • BAdding bulk to food and helping it move through the gut
   • CBuilding new muscle protein
   • DSupplying calcium for strong bones

   (b)

   Which statement best describes a balanced diet?

   [1 mark]

   • AEating the right types and amounts of nutrients needed to stay healthy
   • BEating as little food as possible each day
   • CEating only carbohydrate-rich foods for energy
   • DEating only foods labelled as low-fat

   (c)

   Explain why the worker's low fibre and low water intake, together, are likely reasons for his constipation.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A school health poster project must describe the accessory organs of the digestive system, the salivary glands, pancreas, liver and gall bladder, and explain how each contributes to digestion even though none of them forms part of the alimentary canal itself.

   (a)

   Which of these accessory organs stores bile before it is released into the small intestine?

   [1 mark]

   • APancreas
   • BSalivary glands
   • CGall bladder
   • DLiver

   (b)

   Which accessory organ produces the amylase found in saliva?

   [1 mark]

   • ASalivary glands
   • BPancreas
   • CLiver
   • DGall bladder

   (c)

   Explain the difference in role between the liver and the gall bladder in relation to bile.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A dental hygienist is teaching a group of children about their teeth, explaining the roles of incisors, canines, premolars and molars in physically breaking down food, and why keeping the outer covering of each tooth healthy matters.

   (a)

   Describe the structure of a human tooth, and explain the function of the enamel layer.

   [3 marks]

   (b)

   Compare the functions of incisors and molars in physical digestion, and explain why physical digestion, by teeth and later by the churning action of the stomach, is essential for effective chemical digestion later in the gut.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A nutrition class traces what happens to a ham and cheese sandwich, containing protein from the ham, fat from the cheese, and starch from the bread, as it passes through the digestive system, focusing on how each type of food molecule is digested.

   (a)

   Explain how the starch in the bread and the protein in the ham are each chemically digested as the sandwich passes through the digestive system, naming the enzymes involved and where each acts.

   [6 marks]

   (b)

   Explain how the fat in the cheese is digested, including the role of bile, and explain why physical digestion by chewing and by the churning action of the stomach is especially important for preparing the fat and protein in this sandwich for chemical digestion.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A food scientist analyses fluid samples taken from three points along a new artificial digestion rig, testing each for the presence of specific digestive enzymes, to check that the rig accurately mimics chemical digestion in the human gut.

   (a)

   Which enzyme would the scientist expect to find breaking down starch into simple sugars in a sample taken near the start of the rig?

   [1 mark]

   • ALipase
   • BProtease
   • CAmylase
   • DBile

   (b)

   A later sample from the rig contains a substance that is not itself an enzyme but instead emulsifies fat, increasing its surface area for enzyme action. What is this substance?

   [1 mark]

   • AProtease
   • BAmylase
   • CPepsin
   • DBile

   (c)

   Explain the difference between the digestion of starch by amylase and the further digestion of maltose by maltase.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A premature baby's small intestine has fewer, less well-developed villi than a full-term baby's. Doctors monitor how efficiently the baby absorbs nutrients from its feeds, expecting absorption to improve as the gut continues to develop over the following weeks.

   (a)

   What is the main function of villi in the small intestine?

   [1 mark]

   • ATo produce digestive enzymes
   • BTo increase the surface area for absorption
   • CTo store undigested food
   • DTo produce bile

   (b)

   Which structures inside each villus absorb the products of fat digestion?

   [1 mark]

   • ACapillaries
   • BXylem vessels
   • CGoblet cells
   • DLacteals

   (c)

   Explain why the premature baby's fewer, less developed villi are likely to absorb nutrients less efficiently than a full-term baby's, and why this absorption is expected to improve as the baby's gut matures.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A gastroenterologist explains to a patient recovering from a severe bout of diarrhoea that most of the water in digested food is normally absorbed as it passes through the gut, and that dietary fibre plays an important role in maintaining normal gut function.

   (a)

   Describe where most of the water in digested food is normally absorbed as it passes through the gut.

   [3 marks]

   (b)

   Explain the normal role of fibre in gut function, and explain why severe diarrhoea disrupts the normal absorption of water described above.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A marathon runner eats a meal of pasta, providing mostly starch, together with grilled chicken, providing protein, shortly after finishing a race, aiming to replace her muscles' energy stores and begin repairing muscle tissue as quickly as possible.

   (a)

   Explain, in order, the full pathway followed by the starch in the pasta, from ingestion through to the absorption of glucose into the runner's blood, and explain why this pathway makes glucose available relatively quickly to help replace the energy used during the race.

   [6 marks]

   (b)

   Explain, in order, the full pathway followed by the protein in the chicken, from ingestion through to the absorption of amino acids, and explain why absorbing these amino acids quickly is important for repairing the runner's muscle tissue after the race.

   [6 marks]

   Total for question 8: 12 marks

End of questions