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DP IB Biology: HL

Topic Questions

Home / IB / Biology: HL / DP / Topic Questions / 2. Molecular Biology / 2.3 Proteins / Structured Questions: Paper 2


2.3 Proteins

Question 1a

Marks: 1
a)
The image below shows the amino acid histidine.
e-1a

Circle the section of the amino acid that is unique to histidine. 

[1 mark]

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    Question 1b

    Marks: 1
    b)
    State the type of reaction that occurs when two amino acids bond with each other. 
    [1 mark]
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      Question 1c

      Marks: 1
      c)

      The image shows two histidine amino acids with the diagrams not fully complete. 

      Complete the image to include the structure of a peptide bond joining the two amino acids together into a dipeptide.

      e-1c

       

      [1 mark]

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        Question 1d

        Marks: 1
        d)
        In a polypeptide with 100 amino acids, how many peptide bonds exist within the chain? 
        [1 mark]
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          Question 2a

          Marks: 2
          a)
          The protein Rubisco is an enzyme. 

          What is the function of the enzyme Rubisco in living organisms? 

          [2 marks]

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            Key Concepts
            Examples of Proteins

            Question 2b

            Marks: 1
            b)
            Enzymes have a specific three-dimensional conformation that enables them to carry out their roles in living organisms. 

            Which part of the amino acid determines the conformation of the protein?

            [1 mark]

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              Question 2c

              Marks: 2
              c)
              In certain conditions, such as high temperatures, the 3D conformation of proteins can be lost. 

              i) What is the scientific name given to when a protein loses its 3D conformation? 

              [1 mark]

              ii) State one condition, other than temperature, that can cause the 3D conformation of a protein to be lost. 

              [1 mark]

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                Key Concepts
                Denaturation: Proteins

                Question 2d

                Marks: 2
                d)
                Sketch a graph to show how the rate of reaction of Rubisco changes over a range of temperatures. 

                Use the axes provided below.

                e-2d

                [2 marks]

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                  Question 3a

                  Marks: 1
                  a)
                  What is the name of the part of the cell where polypeptide synthesis takes place?
                  [1 mark]
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                    Question 3b

                    Marks: 3
                    b)
                    When a polypeptide is synthesised it is important that the amino acids are combined in the correct order to produce a functional protein.

                    Outline the process that allows the amino acids to be added to the polypeptide in the correct order. 

                    [3 marks]

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                      Question 3c

                      Marks: 3
                      c)
                      After a polypeptide has been synthesised it must undergo a series of changes before it can become a functional protein.

                      Describe the changes that occur between polypeptide synthesis and the formation of the functional protein. 

                      [3 marks]

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                        Question 3d

                        Marks: 2
                        d)
                        How might a change in the DNA affect the way that the process of protein folding occurs? 
                        [2 marks]
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                          Key Concepts
                          Codons
                          Mutation

                          Question 4a

                          Marks: 1
                          a)
                          What is meant by the term proteome?
                          [1 mark]
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                            Key Concepts
                            Proteome

                            Question 4b

                            Marks: 2
                            b)
                            There are two main categories of proteins: globular and fibrous. 

                            The protein insulin is a hormone.

                            State whether insulin is a globular or a fibrous protein, and give a reason for your choice. 

                            [2 marks]

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                              Question 4c

                              Marks: 2
                              c)

                              The image below shows the structure of collagen at various levels of detail. 

                              collagen-sq

                              Use the image to suggest two features of collagen that enable it to be a strong, structural protein. 

                              [2 marks]

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                                Key Concepts
                                Examples of Proteins

                                Question 4d

                                Marks: 3
                                d)
                                One of the polypeptide chains that forms a molecule of collagen contains 1049 peptide bonds.

                                Assuming all the chains that form collagen are identical in length, how many amino acids would be found in a single molecule of collagen?

                                Explain your answer. 

                                [3 marks]

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                                  Question 5a

                                  Marks: 3

                                  One mark is available for clarity of communication throughout this question. 

                                  a)
                                  Every individual has a unique proteome.

                                  Explain how this is possible. 

                                  [3 marks]

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                                    Key Concepts
                                    Proteome

                                    Question 5b

                                    Marks: 4
                                    b)
                                    Describe the process of protein denaturing. 
                                    [4 marks]
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                                      Key Concepts
                                      Denaturation: Proteins