A LevelBiologyCIEExam Questions8. Transport in Mammals8.2 Transport of Oxygen & Carbon Dioxide

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First exams 2025

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Transport of Oxygen & Carbon Dioxide (CIE A Level Biology)

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8.2 Transport of Oxygen & Carbon Dioxide

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8.2 Transport of Oxygen & Carbon Dioxide

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11 mark

As blood passes through the capillaries of the lungs the uptake of oxygen is maximised.

Which of the statements below explain how this happens?

  • The dissociation of carbon dioxide from carboxyhaemoglobin allows more haemoglobin to be available for oxygen binding.

  • The binding of the first oxygen molecule to haemoglobin decreases the affinity of the molecule for binding other oxygen molecules.

  • Oxyhaemoglobin formation increases the capacity of red blood cells to transport oxygen.

  • Each haemoglobin molecule can temporarily bind to four oxygen atoms.

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21 mark

Carbonic anhydrase catalyses a reaction involved in the transport of carbon dioxide.

What happens after this reaction has taken place?

  • The formation of carbon dioxide from carbonic acid

  • The formation of oxyhaemoglobin from haemoglobin and oxygen

  • The dissociation of oxyhaemoglobin to haemoglobin and oxygen

  • The formation of carbaminohaemoglobin to haemoglobin and oxygen

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31 mark

Which of the following is a correct statement about the transport of carbon dioxide by blood?

1 Carbon dioxide dissociates forming hydrogen ions that combine with haemoglobin to form carbaminoglobin.
2 Carbon dioxide diffuses from respiring cells to red blood cells and reacts with water.
3 The enzyme carbonic anhydrase catalyses the formation of carbonic acid in red blood cells.

  • 1, 2 and 3

  • 1 and 3

  • 1 and 2

  • 2 and 3

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41 mark

Which of the following could be a result of lower concentrations of carbonic anhydrase?

  • Less oxygen is released from oxyhaemoglobin in respiring tissue.

  • The pH of the blood will be lowered.

  • Carbaminohaemoglobin concentrations will decrease.

  • The rate of dissociation of carbonic acid is increased.

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51 mark

Which of the following reactions will take place in the blood of a capillary next to an alveolus in the lungs?

1

H2O + CO2 → H2CO3

2

Hb + 4O2 → HbO8

3

HHb + 4O2 → HbO8 + H+

  • 1 only

  • 2 only 

  • 1 and 2

  • 2 and 3

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61 mark

Which of the following can be carried out by a mature red blood cell?

  • Protein synthesis

  • Cell division

  • Phagocytosis

  • Active transport

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71 mark

Haemoglobin can bind to carbon dioxide, oxygen and carbon monoxide.

Which of the following statements about the binding sites on a haemoglobin molecule is correct?

  • Carbon dioxide and carbon monoxide bind to one site, oxygen binds to a different site.

  • Carbon monoxide and oxygen bind to one site, carbon dioxide binds to a different site.

  • Carbon dioxide and oxygen bind to one site, carbon monoxide binds to a different site.

  • Carbon dioxide, carbon monoxide and oxygen all bind to different sites.

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81 mark

The properties of haemoglobin change as a result of the Bohr effect.

Which row of the table below correctly describes these changes?

  affinity for oxygen by haemoglobin oxygen dissociates from haemoglobin
A lower less readily
B lower more readily
C higher less readily
D higher more readily

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    91 mark

    Carbonic anhydrase is an enzyme.

    What is produced as a result of the action of carbonic anhydrase?

    • Oxyhaemoglobin

    • Carbaminohaemoglobin

    • Haemoglobinic acid

    • Hydrogen carbonate ions

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    101 mark

    The Bohr effect describes a relationship between haemoglobin, oxygen and carbon dioxide.

    Which statement best describes this effect?

    • In low partial pressure of oxygen and high partial pressure of carbon dioxide, the affinity of haemoglobin for oxygen decreases.

    • In high partial pressure of oxygen and high partial pressure of carbon dioxide, the affinity of haemoglobin for oxygen increases.

    • In low partial pressure of oxygen and low partial pressure of carbon dioxide, the affinity of haemoglobin for oxygen is unchanged.

    • In high partial pressure of oxygen and low partial pressure of carbon dioxide, the affinity of haemoglobin for oxygen decreases.

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    11 mark

    The percentage saturation of haemoglobin with oxygen changes at different partial pressures of oxygen. 

    The graph below shows this change in two different concentrations of carbon dioxide.

    q11-cie-8-2

    What of the following would be a correct effect of increasing the carbon dioxide concentration?

    • It increases the dissociation of oxygen from haemoglobin in respiring tissues

    • It increases the affinity of haemoglobin for oxygen at respiring tissues.

    • It increases the inhibition of carbonic anhydrase enzyme in red blood cells.

    • It increases the dissociation of haemoglobinic acid inside red blood cells.

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    21 mark

    Oxygen is displaced from oxyhaemoglobin.

    Which of the following substances will encourage this displacement?

    1 hydrogen ions
    2 hydrogen carbonate ions
    3 carbon monoxide  
    4 carbon dioxide

    • 1 and 2

    • 1 and 3

    • 2 and 3

    • 2 and 4

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    31 mark

    When carbon dioxide levels increase in human blood, the oxyhaemoglobin dissociation curve shifts to the right.

    Which of the following statements explains this effect?

    • Diffusion of carbon dioxide between the alveoli and the blood is more rapid

    • Increasing the H+ concentration decreases haemoglobin affinity for oxygen

    • Carbon dioxide is more soluble than oxygen and displaces it

    • An increase in carbon dioxide concentration increases the ventilation rate

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    41 mark

    The photograph below shows a type of blood cell.

    screenshot-2023-05-13-171459

    Which of the following statements about these cells are correct?

         1      Water passes in and out of these cells by osmosis.

         2      Oxygen diffuses through the phospholipid bilayer.

         3     Sodium ions diffuse through the phospholipid bilayer.

    • 1 and 2

    • 1 and 3

    • 2 and 3

    • 1, 2 and 3

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    51 mark

    Different animals have differing percentage saturation of haemoglobin at the same partial pressures. 

    The graph below shows this difference between a human and vertebrate Y. The partial pressure of CO2 remains constant at 1.0 kPa and the temperature constant at 25 ËšC.

    q15-cie-8-2

    Which of the following conclusions is supported by the data in the graph?

    • Haemoglobin does not become fully saturated in the lungs of vertebrate Y.

    • The Bohr effect in the haemoglobin of vertebrate Y is greater than in human haemoglobin.

    • Oxygen is more easily released from haemoglobin in the muscle of vertebrate Y than in human muscle.

    • At the temperature of 25 °C the affinity of haemoglobin for oxygen increases more in humans than in vertebrate Y.

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    61 mark

    The graph below shows the oxygen dissociation curve for human haemoglobin.

    q16-cie-8-2

     What range of partial pressures of oxygen would be found in pulmonary arteries?

    • from 0 to 2 kPa

    • from 2 to 6 kPa

    • from 6 to 8 kPa

    • from 8 to 12 kPa

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    71 mark

    The graph below is the oxygen dissociation curve for human haemoglobin in different concentrations of carbon dioxide.

    Which letter represents the oxygen concentration of red blood cells as they leave a resting muscle?

    cQgRwgM5_q17-cie-8-2

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      81 mark

      The following are reactions that take place in blood.

      1 HbO8 → Hb + 4O2
      2 HbO8 + H+ → HHb + 4O2     
      3 HCO3- + H+ → H2CO3
      4 H2O + CO2 → H2CO3

      Which of these will take place in blood passing through active tissues?

      • 1, 3 and 4

      • 1, 2 and 3

      • 2 and 3

      • 1, 2 and 4

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      91 mark

      The graph shows the oxygen dissociation curves for human haemoglobin in three different concentrations of carbon dioxide.

      q-19-cie-8-2

      What is the effect of carbon dioxide on haemoglobin?

      • It makes it more efficient at taking up oxygen and also more efficient at releasing it

      • It makes it more efficient at taking up oxygen and less efficient at releasing it

      • It makes it less efficient at taking up oxygen and also less efficient at releasing it.

      • It makes it less efficient at taking up oxygen and more efficient at releasing it

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      101 mark

      The graph below shows the oxygen dissociation curve for human haemoglobin.

      q20-cie-82

      Which letter shows the range of partial pressures that produce the greatest change of percentage saturation of haemoglobin per oxygen unit tension?

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        11 mark

        The graph shows the oxygen dissociation curves for human haemoglobin at two different pHs.

        screenshot-2023-05-13-192858

        Which curve shows the lowest pH and in which tissue might have this data been collected?

          lower pH Tissue
        A curve 2 active muscle
        B curve 2 resting muscle
        C curve 1 active muscle
        D curve 1 resting muscle

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          21 mark

          The diagram shows the transportation of carbon dioxide by red blood cells.diagram-8

          Which row shows the correct compounds at each stage?

           

          1

          2

          3

          4

          A

          carbamino-haemoglobin

          haemoglobic acid

          hydrogen ions

          hydrogen carbonate ions

          B

          carbonic anhydrase

          carbonic acid

          hydrogen carbonate ions

          hydrogen ions

          C

          carbamino-haemoglobin

          carbonic anhydrase

          carbonic acid

          carbon dioxide

          D

          carbonic anhydrase

          carbonic acid

          hydrogen ions

          hydrogen carbonate ions

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            31 mark

            The diagram shows a red blood cell with the concentration of ions, in mmol dm-3, inside and outside the cell.

            screenshot-2023-05-13-194302

             

            Which row shows the correct direction of active transport?

              into cell out of cell
            A Cl- K+
            B Na+ Cl-
            C Na+ K+
            D K+ Na+

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              41 mark

              The graph below shows the oxygen dissociation curves for human haemoglobin and myoglobin.

              screenshot-2023-05-13-194748

              Which statement correctly compares myoglobin and haemoglobin at a partial pressure of oxygen of 2 kPa?

              • Haemoglobin has a lower affinity for oxygen than myoglobin.

              • Haemoglobin combines with more oxygen than myoglobin.

              • Haemoglobin has a saturation of 20% when myoglobin is fully saturated.

              • Haemoglobin combines with oxygen when myoglobin releases oxygen.

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              51 mark

              The graph below shows the oxygen dissociation curves for haemoglobin in three different animals.

              screenshot-2023-05-13-195319

              Which of the haemoglobins R, S or T would be present in each of the animals shown in the list below?

              1

              An adult human.

              2

              A fish living in water that has a very low oxygen concentration.

              3

              A very active mammal whose tissues have a much higher rate of respiration than an adult human.
                1 2 3
              A T S R
              B S T R
              C S R T
              D R S T

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                61 mark

                Active muscles have a higher respiration rate than resting muscles. The graph below shows the oxygen dissociation curves for haemoglobin for resting muscle and active muscle.

                • W and X are at the partial pressures of oxygen found in the lungs
                • Y and Z are at the partial pressures of oxygen found in either a resting muscle or an active muscle

                screenshot-2023-05-13-195629

                Which of the following statements are correct?

                1

                The % saturation at X minus the % saturation at Y represents the amount of oxygen delivered to a resting muscle.

                2

                The % saturation at W minus the % saturation at X represents the amount of oxygen delivered to an active muscle.

                3

                The % saturation at X represents the amount of oxygen carried to an active muscle.

                4

                The % saturation at Z represents the amount of oxygen required by a resting muscle.

                5

                The % saturation at W minus the % saturation at Y represents the amount oxygen delivered to a resting muscle

                • 1 and 3

                • 1 and 4

                • 2 only

                • 5 only

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                71 mark

                The graph below shows the oxygen dissociation curves for haemoglobin at different partial pressures of carbon dioxide.

                screenshot-2023-05-13-200136

                Which of the following shows the correct percentage change in percentage saturation of haemoglobin at a partial pressure of 6 kPa between the partial pressures of carbon dioxide from 1.0 kPa and 1.5 kPa?

                • 46%

                • 20%

                • -20%

                • -26%

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                81 mark

                The graph shows the Bohr effect

                screenshot-2023-05-13-200550

                 

                Which of the following explains the shift from S to T?

                • Increased concentration of carbon dioxide and low pH.

                • Increased concentration of carbon dioxide and high pH.

                • Decreased concentration of carbon dioxide and low pH.

                • Decreased concentration of carbon dioxide and high pH.

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                91 mark

                The partial pressure of oxygen decreases as altitude increases from sea level.

                Which row of the table below correctly describes the reason for the response of the body at high altitude?

                 

                description

                reason

                A

                red blood cells have genes switched on

                so red blood cells produce more haemoglobin

                B

                oxygen dissociation curve shifts to the right

                to compensate for an increase in oxygen unloading in tissues

                C

                percentage saturation of haemoglobin with oxygen in lungs decreases

                so more red blood cells are produced to carry more haemoglobin

                D

                more red blood cells

                because haemoglobin breaks down more rapidly

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                  101 mark

                  The following events happen when carbon dioxide enters an erythrocyte in a capillary.

                  1

                  Hydrogen carbonate ions diffuse into the plasma from the erythrocyte.

                  2

                  Dissociation of carbonic acid.

                  3

                  Carbon dioxide reacts with water forming carbonic acid.

                  4

                  Chloride ions diffuse into erythrocytes from plasma.

                  Which row in the table below shows the correct sequence of events?

                   

                  first step              →                   →                 last step

                  A

                  2

                  4

                  1

                  3

                  B

                  3

                  2

                  1

                  4

                  C

                  3

                  1

                  4

                  2

                  D

                  2

                  3

                  4

                  1

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