1. 1
   Before a marathon, a runner eats a meal high in pasta and rice. Her nutritionist explains that this will provide a store of energy in the form of large carbohydrate molecules, broken down during the race to release simple sugar molecules for respiration.

   (a)

   Which three elements are found in carbohydrates such as the starch in pasta and rice?

   [1 mark]

   • ACarbon, hydrogen, oxygen
   • BCarbon, hydrogen, nitrogen
   • CCarbon, oxygen, nitrogen
   • DCarbon, hydrogen, sulfur

   (b)

   Which molecule is the simple sugar monomer that joins together to form the starch in the pasta and rice, and is also used as the substrate for respiration during the race?

   [1 mark]

   • AGlycerol
   • BAmino acid
   • CGlucose
   • DFatty acid

   (c)

   Describe how simple sugar molecules join together to form the starch found in the pasta and rice, and explain why starch is a useful energy store for the runner.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A dietitian explains to a patient that dietary fats, once digested into their component parts, are essential for building cell membranes throughout the body, as well as for insulation and long-term energy storage.

   (a)

   What are lipids made of, once broken down into their component parts?

   [1 mark]

   • AAmino acids only
   • BGlycerol and fatty acids
   • CGlucose molecules only
   • DNucleotides

   (b)

   Which elements are found in the lipids described by the dietitian?

   [1 mark]

   • AOxygen and nitrogen only
   • BCarbon, hydrogen and nitrogen
   • CCarbon and nitrogen only
   • DCarbon, hydrogen and oxygen

   (c)

   Describe two functions of lipids in the human body mentioned by the dietitian.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A doctor examines a malnourished patient with a very low protein intake, and notices muscle wasting, a weakened immune response and poor wound healing, all linked to a shortage of protein-based molecules in the body.

   (a)

   Describe proteins as polymers of amino acids, and explain how a shortage of protein-based molecules could cause the muscle wasting and weakened immune response seen in the patient.

   [3 marks]

   (b)

   Explain, using named examples, how the structure of a protein is related to its function in the body.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Food scientists in a testing laboratory analyse three unlabelled samples of biological molecules extracted from different foods, and use their knowledge of the building blocks of carbohydrates, lipids and proteins to identify each sample.

   (a)

   Describe carbohydrates, lipids and proteins in terms of the elements they contain and their basic building block units.

   [6 marks]

   (b)

   Describe the functions of carbohydrates, lipids and proteins in living organisms, and explain how the structure of a protein is related to its function.

   [6 marks]

   Total for question 4: 12 marks

End of questions