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Exam questions · Biology · The Circulatory System

Blood

  • 7 exam questions
  • 18 marks
  • 8 quick checks
  1. 1 State [1 mark]

    Name the part of the blood that carries oxygen.

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    Model answer

    Red blood cells (haemoglobin in the red blood cells).

    Mark scheme

    • Red blood cells — 1 mark
  2. 2 Name [3 marks]

    Figure 1 shows some of the components of blood. Name the parts labelled A, B and C.

    A drop of blood with three parts marked A, B and C.
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    Model answer

    A is a red blood cell. B is a white blood cell. C is a platelet.

    Mark scheme

    • A: red blood cell — 1 mark
    • B: white blood cell — 1 mark
    • C: platelet — 1 mark
  3. 3 State [2 marks]

    Name two substances carried in the plasma, and state where each one is carried to.

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    Model answer

    Carbon dioxide is carried to the lungs. Urea is carried to the kidneys. Accept glucose carried to the body cells, or hormones carried to their target organs.

    Mark scheme

    • A named substance — 1 mark
    • Its correct destination — 1 mark
  4. 4 Explain [3 marks]

    Explain how a red blood cell is adapted to carry oxygen.

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    Model answer

    It contains haemoglobin, which joins with oxygen. It has no nucleus, so there is more room for haemoglobin. Its biconcave shape gives a large surface area for oxygen to diffuse in and out.

    Mark scheme

    • Contains haemoglobin — 1 mark
    • No nucleus so more room for haemoglobin — 1 mark
    • Biconcave shape gives a large surface area — 1 mark
  5. 5 Describe [2 marks]

    Describe the function of platelets.

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    Model answer

    Platelets help the blood to clot at a wound. The clot forms a scab that stops the bleeding and prevents microorganisms entering.

    Mark scheme

    • Help the blood to clot — 1 mark
    • Stops blood loss / stops pathogens getting in — 1 mark
  6. 6 Describe [3 marks]

    A photograph of blood shows many small round cells, a few much larger cells with a dark purple centre, and some tiny fragments. Describe how you can identify each of these using what you know about blood cells.

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    Model answer

    The many small round cells with no nucleus are red blood cells. The few larger cells with a dark stained nucleus are white blood cells. The tiny fragments with no nucleus are platelets.

    Mark scheme

    • Small round cells with no nucleus are red blood cells — 1 mark
    • Larger cells with a nucleus are white blood cells — 1 mark
    • Tiny fragments are platelets — 1 mark
  7. 7 Evaluate [4 marks]

    Blood transfusions use blood products from donors. Evaluate the risks and benefits of using blood products.

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    Model answer

    A transfusion can save the life of a person who has lost a lot of blood or who has a blood disorder. However, there are risks. The donor blood could be infected with a pathogen, although screening reduces this risk. If the blood group is not matched, the patient can have a serious reaction. Some patients may have an allergic reaction. On balance the benefits usually outweigh the risks because blood is screened and matched.

    Mark scheme

    • Benefit: saves life / replaces lost blood — 1 mark
    • Risk: infection from donor blood — 1 mark
    • Risk: mismatched blood group / allergic reaction — 1 mark
    • A conclusion weighing risks and benefits — 1 mark

Quick check

  1. 1

    Which part of the blood carries oxygen?

    1. APlasma
    2. BRed blood cells
    3. CWhite blood cells
    4. DPlatelets
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    B: Red blood cells

    Red blood cells contain haemoglobin, which joins with oxygen.

  2. 2

    Which part of the blood helps it to clot?

    1. APlasma
    2. BRed blood cells
    3. CWhite blood cells
    4. DPlatelets
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    D: Platelets

    Platelets are cell fragments that help blood clot at a wound.

  3. 3

    Which blood cell has a nucleus?

    1. ARed blood cell
    2. BPlatelet
    3. CWhite blood cell
    4. DNone of them
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    C: White blood cell

    White blood cells have a nucleus. Red blood cells and platelets do not.

  4. 4

    What is carried in the plasma from the liver to the kidneys?

    1. AUrea
    2. BOxygen
    3. CPlatelets
    4. DHaemoglobin
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    A: Urea

    Urea is made in the liver and carried in the plasma to the kidneys.

  5. 5

    Why do red blood cells have no nucleus?

    1. ATo make them heavier
    2. BTo make more room for haemoglobin
    3. CTo help them divide
    4. DTo make them larger
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    B: To make more room for haemoglobin

    It leaves more room for haemoglobin, so the cell can carry more oxygen.

  6. 6

    What is the red pigment in red blood cells?

    1. AChlorophyll
    2. BPlasma
    3. CHaemoglobin
    4. DAntibody
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    C: Haemoglobin

    Haemoglobin joins with oxygen in the lungs and releases it in the tissues.

  7. 7

    What do phagocytes do?

    1. ACarry oxygen
    2. BMake platelets
    3. CCarry carbon dioxide
    4. DEngulf pathogens
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    D: Engulf pathogens

    Phagocytes are white blood cells that engulf and digest pathogens.

  8. 8

    Which component of blood is a fragment of a cell?

    1. APlatelets
    2. BRed blood cells
    3. CWhite blood cells
    4. DPlasma
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    A: Platelets

    Platelets are small fragments of cells with no nucleus.