Biology 9700 · AS & A Level · Transport of oxygen and carbon dioxide

Transport of oxygen and carbon dioxide — practice question

In mammals, oxygen is carried by red blood cells within a system called double circulation. Most oxygen molecules travel as oxyhaemoglobin. In respiring tissues, oxygen leaves haemoglobin and diffuses into nearby cells.
(a)[2]

Explain what is meant by a closed double circulation.

(b)

Fig. 3.1 is a diagram showing the tertiary and quaternary structure of a haemoglobin molecule.

(c)[4]

Explain how the tertiary and quaternary protein structure of haemoglobin helps it transport oxygen.

(d)[2]

After a period at altitude, a person may become acclimatised. One feature of acclimatisation is an increase in the red blood cell count. Explain the importance of this increase in the red blood cell count.

(e)[3]

Before acclimatisation takes place, some people develop acute mountain sickness when they travel to high altitude areas. Acetazolamide is a non-competitive enzyme inhibitor used as a drug to prevent and treat acute mountain sickness. Explain the effect of a non-competitive inhibitor on the rate of enzyme activity.

(f)[3]

Using Fig. 3.3 as a reference, describe how carbon monoxide affects the cardiovascular system.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Blood stays in vessels and the heart (arteries, veins, capillaries)

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