1. 1
   A food scientist is testing samples of saliva and pancreatic juice to identify which digestive enzymes are present and what they act on.

   (a)

   Which enzyme breaks down starch into simple reducing sugars?

   [1 mark]

   • AAmylase
   • BProtease
   • CLipase
   • DMaltase

   (b)

   Which substance is broken down into fatty acids and glycerol by lipase?

   [1 mark]

   • AStarch
   • BProtein
   • CFats and oils
   • DMaltose

   (c)

   State what is meant by chemical digestion, and explain why this process is necessary for nutrients to be absorbed into the blood.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A patient's digestive juices are being analysed at two points: the stomach and the duodenum, to compare the pH conditions and enzymes present at each site.

   (a)

   Which region of the digestive system has an acidic pH suitable for pepsin activity?

   [1 mark]

   • AMouth
   • BStomach
   • CDuodenum
   • DColon

   (b)

   Which protease acts in the alkaline conditions of the small intestine?

   [1 mark]

   • APepsin
   • BAmylase
   • CLipase
   • DTrypsin

   (c)

   Describe the function of hydrochloric acid in gastric juice.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is tracing how starch and protein in a meal are chemically digested, and how bile helps prepare the mixture leaving the stomach for further digestion.

   (a)

   Describe the digestion of starch as it passes from the mouth to the small intestine, naming the enzymes involved and their products.

   [3 marks]

   (b)

   Explain why bile is needed for effective chemical digestion in the duodenum, referring to both its neutralising role and the digestion of protein in this region.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A nutritionist is explaining to a client the complete journey of chemical digestion for a mixed meal of starch, protein and fat, and how the digestive system ensures nutrients can be absorbed.

   (a)

   A meal containing starch, protein and fat passes through the digestive system. Explain, in order, the chemical digestion this meal undergoes from the mouth to the small intestine, naming the enzymes involved, their substrates, their products, and the conditions (pH) required for each to work effectively.

   [6 marks]

   (b)

   Explain why enzymes are essential for chemical digestion and why different digestive enzymes are secreted in different regions of the digestive system, each requiring specific conditions to function effectively.

   [6 marks]

   Total for question 4: 12 marks

End of questions