0%

DP IB Biology: HL

Topic Questions

Home / IB / Biology: HL / DP / Topic Questions / 6. Human Physiology / 6.2 The Blood System / Structured Questions: Paper 2


6.2 The Blood System

Question 1a

Marks: 2
a)

Based on your knowledge of diffusion, explain why multicellular organisms need a specialised transport system.

[2 marks]

    Assess your score
      

    Question 1b

    Marks: 2
    b)

    The following table shows the volume of blood present in the left ventricle of a person at different times over the course of one second.

    Time / s Volume of blood in left ventricle / cm3
    0.0 105
    0.1 117
    0.2 89
    0.3 63
    0.4 45
    0.5 55
    0.6 87
    0.7 105
    0.8 119
    0.9 90
    1.0 62

    Use the information in the table to calculate the heart rate (beats min-1) of this person. Show your working.

    [2 marks]

      Assess your score
        
      Key Concepts
      Cardiac Cycle

      Question 1c

      Marks: 2
      c)

      During ventricular systole, the muscular wall of the ventricles contract.

      i)

      Based on the information provided in the table in part a), determine during which time interval(s) the heart was in ventricular systole.

      [1 mark]

      ii)

      Explain your answer in part i).

      [1 mark]

        Assess your score
          
        Key Concepts
        Cardiac Cycle

        Question 2a

        Marks: 3
        a)

        A group of students investigated the effect of a person's fitness level on the heart rate before, during and after exercising. They measured the resting heart rate of an unfit person leading a sedentary lifestyle and that of a trained athlete. After monitoring their resting heart rate for 10 minutes, both participants were asked to run for a period of 10 minutes. Their heart rates were monitored during this time by a heart rate monitor that was attached to their wrists. After exercising, their heart rates were monitored for a period of 40 minutes.

        The results of this investigation is shown in the following graph.

        Y8Z2iXwH_h-2a

         Contrast the results of the two participants.

        [3 marks]

          Assess your score
            

          Question 2b

          Marks: 3
          b)

          Explain the mechanisms that caused the change in heart rate that was observed after the exercise ended.

          [3 marks]

            Assess your score
              

            Question 2c

            Marks: 3
            c)

            The group of students concluded that an increased fitness level enables the heart to recover more quickly after exercise.

            Evaluate the conclusion of the students.

            [3 marks]

              Assess your score
                

              Question 3a

              Marks: 2
              a)

              Ebstein's anomaly is a birth defect where the tricuspid valve is displaced from its normal position between the right atrium and ventricle. This defect will often cause the valve to not function properly. Babies born with Ebstein's anomaly will require surgery to correct the defect.

              The following diagram compares the structure of a normal heart with the heart of a person born with Ebstein's anomaly.h-3a-1

              Explain the effect that a faulty heart valve may have on the flow of blood through the right side of the heart.

              [2 marks]

                Assess your score
                  

                Question 3b

                Marks: 2
                b)

                Babies born with Ebstein's anomaly will often develop an enlarged heart and swollen limbs once they reach adulthood.

                Based on the information provided in part a), suggest a reason for each of these symptoms.

                [2 marks]

                  Assess your score
                    

                  Question 3c

                  Marks: 2
                  c)

                  Tricuspid valve surgery is a very effective way to treat patients born with Ebstein's anomaly and restore heart function back to normal. One way to measure the effectiveness of this treatment is to investigate the increase in cardiac output before and after surgery.

                  Cardiac output is the amount of blood that the heart pumps per minute.

                  A patient born with Ebstein's anomaly has a mean heart rate of 78 beats per minute and with every heart beat, 45 cm3 of blood leaves the heart.

                  Calculate the cardiac output (dm3min-1) of this patient. Show your working.

                  [2 marks]

                    Assess your score
                      

                    Question 3d

                    Marks: 1
                    d)

                    After the surgery, the cardiac output of the patient from part c) increased by 25%.

                    Calculate the cardiac output (dm3min-1) after surgery.

                    [1 mark]

                      Assess your score
                        

                      Question 4a

                      Marks: 2
                      a)

                      Carnitine is a chemical that plays an essential role in energy metabolism by transporting long-chain fatty acids into mitochondria in cells where they are then oxidised. It is often used as a supplement by athletes to enhance their athletic performance and to aid in weight loss.

                      Recent studies have linked the prolonged use of carnitine supplements with increased levels of trimethylamine N-oxide (TMAO) in the bloodstream. TMAOs can trigger inflammatory and immune responses in the body, as well as elevated blood glucose levels.

                      Based on the information provided, explain why increased TMAO levels could increase the risk of suffering a heart attack.

                      [2 marks]

                        Assess your score
                          
                        Key Concepts
                        Atherosclerosis

                        Question 4b

                        Marks: 1
                        b)

                        Scientists investigated the effect of carnitine in the diet on the plasma concentration of TMAO in mice. Four groups, consisting of ten mice each, were fed one of four possible diets.

                        • Diet 1 - a normal mouse diet with natural carnitine levels 
                        • Diet 2 - a normal mouse diet with added carnitine
                        • Diet 3 - a low carnitine mouse diet
                        • Diet 4 - a normal mouse diet with added carnitine and antibiotics

                        The TMAO levels in the bloodstream of the mice were measured over time and a mean for each group was calculated.

                        Suggest a possible hypothesis for this investigation.

                        [1 mark]

                          Assess your score
                            
                          Key Concepts
                          Atherosclerosis

                          Question 4c

                          Marks: 1
                          c)

                          The results of the investigation described at part b) are shown in the following graph.

                          RkEvF74L_h-4c

                          Explain the results from the group that followed diet 4.

                          [1 mark]

                            Assess your score
                              
                            Key Concepts
                            Atherosclerosis

                            Question 4d

                            Marks: 3
                            d)

                            The scientists concluded that a diet high in carnitine will increase levels of TMAO in the bloodstream in humans.

                            Evaluate this conclusion.

                            [3 marks]

                              Assess your score
                                
                              Key Concepts
                              Atherosclerosis

                              Question 5a

                              Marks: 3

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

                              a)

                              The sinoatrial node (SAN) is considered to be the pacemaker of the heart.

                              Explain this statement.

                              [3 marks]

                                Assess your score
                                  
                                Key Concepts
                                Sinoatrial Node

                                Question 5b

                                Marks: 7
                                b)

                                Outline the pressure changes that occur during one cardiac cycle and the effect this has on the valves in the heart.

                                [7 marks]

                                  Assess your score