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DP IB Biology: HL

Topic Questions

Home / IB / Biology: HL / DP / Topic Questions / 6. Human Physiology / 6.3 Defence Against Infectious Disease / Structured Questions: Paper 2


6.3 Defence Against Infectious Disease

Question 1a

Marks: 1
a)

The following diagram shows part of the blood clotting cascade.

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Enzyme A acts on fibrinogen.

Identify enzyme A.

[1 mark]

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    Question 1b

    Marks: 2
    b)

    Substance B is an insoluble protein formed by fibrinogen.

    i)

    Identify substance B.

    [1 mark]

    ii)

    State the purpose of substance B in the body.

    [1 mark]

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      Question 1c

      Marks: 1
      c)

      Blood clotting is essential for the healing of wounds, but can be life-threatening if it occurs in the coronary arteries.

      Define the term 'coronary arteries'.

      [1 mark]

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        Question 1d

        Marks: 3
        d)

        A blood clot in the coronary arteries is called coronary thrombosis.

        List three risk factors that will increase the chance of developing coronary thrombosis.

        [3 marks]

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          Question 2a

          Marks: 1
          a)

          The diagram below shows the production and role of antibodies in the body.

          2XZAB_g2_e-2a

          Antibodies are produced by cell X.

          Identify cell X.

          [1 mark]

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            Key Concepts
            Antibody Production

            Question 2b

            Marks: 1
            b)

            Antibodies are produced in response to the antigens present on pathogens.

            Define the term 'antigen'.

            [1 mark]

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              Key Concepts
              Antibody Production

              Question 2c

              Marks: 1
              c)

              Antibodies aid the body in fighting pathogens in a number of different ways.

              State one way in which they achieve this.

              [1 mark]

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                Key Concepts
                Antibody Production

                Question 2d

                Marks: 2
                d)

                Antibodies are short-lived, but memory cells remain to provide long term immunity against a second infection by the same type of pathogen.

                Describe the secondary response of the memory cells during an infection by the same type of pathogen.

                [2 marks]

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                  Key Concepts
                  Antibody Production

                  Question 3a

                  Marks: 1
                  a)

                  The diagram below shows the action of penicillin on the bacterial cell wall.

                  cNEcNQz2_e-3a

                  Penicillin is an example of an antibiotic.

                  Define the term 'antibiotic'.

                  [1 mark]

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                    Key Concepts
                    Antibiotics

                    Question 3b

                    Marks: 1
                    b)

                    Penicillin is an example of a commonly used antibiotic. It is produced naturally by a fungus (penicillium) to kill competing bacteria in their environment.

                    Based on the information in the diagram in part a), state the way in which penicillin kills bacteria.

                    [1 mark]

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                      Key Concepts
                      Antibiotics

                      Question 3c

                      Marks: 2
                      c)

                      Other than the process stated at part b), list two processes in prokaryotic cells that antibiotics may target.

                      [2 marks]

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                        Key Concepts
                        Antibiotics

                        Question 3d

                        Marks: 1
                        d)

                        Antibiotics are not effective against viruses since they lack the structure and mechanisms of prokaryotic cells. Certain viral diseases are treated with substances known as antivirals.

                        State the way in which an antiviral works.

                        [1 mark]

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                          Key Concepts
                          Viruses

                          Question 4a

                          Marks: 2
                          a)

                          Skin is the largest organ of the body and forms part of the primary defence against pathogens.

                          List two ways in which the skin defends the body against pathogens.

                          [2 marks]

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                            Key Concepts
                            Skin

                            Question 4b

                            Marks: 1
                            b)

                            Platelets are very important in maintaining the integrity of broken skin as a barrier.

                            Define the term 'platelet'.

                            [1 mark]

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                              Key Concepts
                              Platelets

                              Question 4c

                              Marks: 1
                              c)

                              Platelets are essential in the process of blood clotting.

                              State the role of platelets in response to blood vessel damage.

                              [1 mark]

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                                Key Concepts
                                Platelets

                                Question 5a

                                Marks: 4

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

                                a)

                                Human immunodeficiency virus (HIV) is mainly transmitted by the direct exchange of body fluids.

                                List four ways in which HIV can be transmitted between hosts.

                                [4 marks]

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                                  Question 5b

                                  Marks: 4
                                  b)

                                  Once micro-organisms enter the body, white blood cells called phagocytes will provide the next line of defence.

                                  Outline the way in which phagocytes provide defence against micro-organisms.

                                  [4 marks]

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                                    Key Concepts
                                    White Blood Cells

                                    Question 5c

                                    Marks: 5
                                    c)

                                    An HIV infection will eventually progress into AIDS.

                                    Outline the development of AIDS from an HIV infection.

                                    [5 marks]

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