1. 1
   A biochemist studies how enzymes in the human digestive system break down large protein molecules from food into their smaller building blocks, which the body then uses to build its own new proteins.

   (a)

   A biochemist studies how the enzymes in a digestive system break down large protein molecules from food into their smaller building blocks. Proteins are polymers made up of which type of monomer?

   [1 mark]

   • ANucleotides
   • BAmino acids
   • CGlucose molecules
   • DAlkene monomers

   (b)

   The biochemist explains that each amino acid monomer contains two different functional groups within the same molecule, allowing many amino acids to join together in a chain. Which type of polymerisation joins amino acids together to form a protein?

   [1 mark]

   • ACondensation polymerisation
   • BAddition polymerisation
   • CElectrolysis
   • DCombustion

   (c)

   Explain how different amino acids can combine in the same polymer chain to produce many different proteins, even though the general process of forming the chain is the same each time.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A forensic scientist extracts DNA from a small sample of skin cells found at a crime scene, in order to compare its genetic code with database records and help identify a suspect.

   (a)

   Which statement best describes the overall structure of a DNA molecule?

   [1 mark]

   • ATwo polymer chains made from nucleotide monomers, twisted into a double helix
   • BA single polymer chain made from amino acid monomers
   • CTwo polymer chains made from glucose monomers, arranged side by side
   • DA single small molecule with no repeating units

   (b)

   The forensic scientist explains to a jury that DNA encodes genetic instructions using a specific sequence of building blocks along each strand. What are these building blocks called?

   [1 mark]

   • ANucleotides
   • BAmino acids
   • CFatty acids
   • DMonosaccharides

   (c)

   Explain why DNA is described as essential for life, referring to its role in storing genetic information and its structure as a polymer made from monomers.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biotechnology company is developing a new synthetic material inspired by the structure of natural proteins. Their researchers first review how amino acid monomers combine to form polypeptides before designing their own artificial polymer.

   (a)

   Describe the process of condensation polymerisation of amino acids, referring to the functional groups involved and any small molecule that is released.

   [3 marks]

   (b)

   The researchers then compare how proteins are built from a combination of different amino acid monomers with how DNA is built from a combination of four different nucleotide monomers. Explain how using a small number of different monomer types in each case allows for such a wide range of possible polymer molecules, and discuss why this property is important both for proteins and for DNA.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A genetics museum is designing an exhibit to explain to visitors how natural polymers such as DNA, proteins, starch and cellulose are formed by condensation polymerisation, and how they differ in structure, properties and biological role.

   (a)

   Explain the similarities and differences between DNA and proteins in terms of their monomers, how they are formed, and their overall structure, and explain why each is essential for life.

   [6 marks]

   (b)

   The museum also wants to explain, using starch and cellulose as further examples, how condensation polymerisation can produce natural polymers with very different physical properties, even when built from the same type of monomer. Explain what monomer starch and cellulose are made from, and discuss why studying a range of natural polymers, including proteins, DNA, starch and cellulose, helps scientists understand the general principles of condensation polymerisation.

   [6 marks]

   Total for question 4: 12 marks

End of questions