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DP IB Biology: HL

Topic Questions

Home / IB / Biology: HL / DP / Topic Questions / 8. Metabolism, Cell Respiration & Photosynthesis (HL Only) / 8.2 Cell Respiration / Structured Questions: Paper 2


8.2 Cell Respiration

Question 1a

Marks: 1
a)

Most plants can respire aerobically and anaerobically.  The diagram below shows a summary of anaerobic respiration.

process-a-and-b

State precisely in the cell where Process A occurs.

[1 mark]

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    Key Concepts
    Stages of Respiration

    Question 1b

    Marks: 2
    b)

    The diagram below shows a summary of the processes involved in aerobic respiration. 

    aerobic-respiration

    Explain how Process D enables Process A to continue

    [2 marks]

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      Question 1c

      Marks: 3
      c)

      Aerobic respiration produces more ATP per molecule of glucose than anaerobic respiration. 

      Explain why.

      [3 mark]

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        Question 1d

        Marks: 3
        d)

        Different stages of respiration can be inhibited by a range of substances. DNP is a steroid drug used in the weight loss industry. It inhibits respiration by preventing a proton gradient being maintained across membranes. When added to isolated mitochondria it caused the following effects:

        • Less ATP produced
        • Increase in heat production
        • No change in the uptake of oxygen

             Explain how DNP caused these changes.

        [3 marks]

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          Question 2a

          Marks: 3
          a)

          The Krebs cycle takes place in the mitochondrial matrix. The process releases hydrogen ions which provide a source of energy for the synthesis of ATP, using co-enzymes and carrier proteins.

          Describe the role of co-enzymes and carrier proteins in the production of ATP. 

          [3 marks]

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            Key Concepts
            NAD & FAD
            Krebs cycle

            Question 2b

            Marks: 2
            b)

            The following reaction takes place in the Krebs cycle.

            succinate-enzyme-reaction

            A student investigated the effect of the enzyme inhibitor malonate on this reaction. The structure of malonate is similar to the structure of succinate.

            In the investigation, the student added malonate and the respiratory substrate, pyruvate, to a suspension of isolated mitochondria. She also bubbled oxygen through the suspension.

            Explain why the student used pyruvate and not glucose as a respiratory substrate.  

            [2 marks]

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              Key Concepts
              Glycolysis
              Krebs Cycle

              Question 2c

              Marks: 2
              c)

              Explain how malonate inhibits the formation of fumarate from succinate. 

              [2 marks]

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                Question 2d

                Marks: 2
                d)

                The student measured the uptake of oxygen by the mitochondria during the investigation. The uptake of oxygen decreased when malonate was added.

                Explain why.

                [2 marks]

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                  Question 3a

                  Marks: 2
                  a)

                  A group of scientists measured the mean rate of respiration in soil found under trees and soil that was not from under trees within the same woodland. The mean rate of photosynthesis in leaves was also measured. The measurements were taken throughout a 24 hour period during the summer.  

                  The diagram below shows the scientists' results. 

                  lcstjsko-image

                  Suggest an explanation for the mean rate of respiration in soil not under the trees between midday and sunset. 

                  [2 marks]

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                    Key Concepts
                    Stages of Respiration

                    Question 3b

                    Marks: 2
                    b)

                    The mean rate of respiration is higher in soil under the trees throughout the 24hours. The scientists suggested the mean rate of photosynthesis was the cause of this. 

                    Suggest how the rise in the mean rate of photosynthesis could lead to the rise in the mean rate of respiration in soil under trees

                    [2 marks]

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                      Key Concepts
                      Stages of Respiration

                      Question 3c

                      Marks: 1
                      c)

                      Suggest why there is a delay between the rise in the mean rate of photosynthesis and the rise in the mean rate of respiration. 

                      [1 mark]

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                        Key Concepts
                        Stages of Respiration

                        Question 3d

                        Marks: 2
                        d)

                        State the measurements needed for the scientists to calculate the rate of carbon dioxide production. 

                        [2 marks]

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                          Key Concepts
                          Stages of Respiration

                          Question 4a

                          Marks: 3
                          a)

                          The diagram below shows the main stages of aerobic respiration.

                          8NENyROy_image

                           Name substances A, B and C

                          [3 marks]

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                            Key Concepts
                            Stages of Respiration

                            Question 4b

                            Marks: 2
                            b)

                            Annotate on the diagram,

                            i) with an X, where oxidation occurs

                            ii) with a Y, where decarboxylation occurs

                            [2 marks]

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                              Question 4c

                              Marks: 1
                              c)

                              State precisely where in the cell Process 2 is occurring. 

                              [1 mark]

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                                Question 4d

                                Marks: 2
                                d)

                                Compare the roles of NAD+ and NADH in Process 1 and Process 3.

                                [2 marks]

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                                  Question 5a

                                  Marks: 5

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

                                  a)

                                  A large number of disorders are being linked to mitochondrial disease, MD. MD can affect the skeletal muscles, causing fatigue and weakness. Some mitochondrial diseases are caused by mutations of mitochondrial genes inside the mitochondria. Most mitochondrial diseases are caused by mutations of genes in the cell nucleus that are involved in the functioning of mitochondria. 

                                  One form of MD is caused by a mutation of a mitochondrial gene that codes for a tRNA. which changes the anticodon on the tRNA.  This results in the formation of a non-functional protein in the mitochondrion.

                                  Suggest how a  change in anticodon on the tRNA can lead to muscle weakness and fatigue.

                                  [5 marks]

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                                    Question 5b

                                    Marks: 3
                                    b)

                                    A person with MD often has a decreased uptake of oxygen in their respiring cells. This has been attributed to an inhibitory compound of the Krebs cycle.

                                    Explain why an inhibitor of the Krebs cycle would decrease the rate of oxygen uptake by cells.

                                    [3 marks]

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                                      Question 5c

                                      Marks: 7
                                      c)

                                      Explain the role of chemiosmosis in the process of oxidative phosphorylation 

                                      [7 marks]

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