BiologyMad A-Level Biology



Blood and Circulation Questions

1. The diagram shows some blood vessels in a muscle.

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(a) (i) Name two substances which are at a higher concentration in the blood at point A than in the blood at point D.

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(1)

(ii) The more active a muscle, the greater the blood flow through its capillaries. Explain the advantage of this.

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(2)

(b) (i) Explain why the amount of protein in the blood plasma does not fall when tissue fluid is formed at point B.

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(1)

(ii) Explain the role of the proteins in the blood plasma in returning fluid to the capillary at point C.

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(2)

(Total 6 marks)

2. (a) Explain why a vein is described as an organ.

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(1)

(b) The diagram shows a vein passing between two muscles.

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(i) When the muscles contract, the pressure of the blood in the part of the vein between valves A and B changes. Explain how this change in pressure, together with the action of the valves, helps the blood to flow to the heart

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(3)

(ii) Suggest how blood is returned to the heart when the muscles are not contracting

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(1)

3. (a) Explain why blood may be described as a tissue.

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(1)

(b) The diagram shows how the different types of cells found in human blood may be distinguished from each other.

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Name:

(i) Cell C; ....................................................................................................

(ii) Cell D. ....................................................................................................

(2)

(c) The drawing has been made from an electronmicro graph. It shows a red blood cell in a capillary from a human lung.

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(i) The diameter of the red blood cell is approximately the same as the diameter of the inside of the capillary. Suggest two ways in which this increases the efficiency with which oxygen diffuses from the alveoli into the red blood cell.

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(2)

(ii) The red blood cell is a uniform colour. The nucleus has patches of light and dark colour. Explain this difference in appearance.

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(2)

(Total 7 marks)

4. The diagram shows the relative thickness of components of the walls of some blood vessels.

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(a) Explain how the structure of the wall of an artery evens out the arterial blood flow.

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(2)

(b) The body responds to an increase in blood temperature by increasing the flow of blood through the capillaries in the skin. Use the information in the diagram to explain what brings about this increase in blood flow.

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(2)

(Total 4 marks)

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