Biology 9700 · AS & A Level · The gas exchange system
The gas exchange system — practice question
Pneumonia is a serious disease of the lungs that can disrupt gas exchange. A person who has pneumonia may be attached to an ECMO machine. This machine carries out the gas exchange roles of the lungs. A cannula (tube) is inserted into the right atrium and carries blood to the ECMO machine. Inside the ECMO machine, the blood is sent first to an artificial pump and then to an oxygenator, where gas exchange takes place. The blood is then warmed and returned by a second cannula to the vena cava.
(a)[1]
Complete Fig. 5.1 to show the way the ECMO machine is joined to the right atrium and to the vena cava. Show each cannula using a single line.
(b(i))[1]
State the name of a structure in the gas exchange system that performs the same role as the partially permeable membrane of the oxygenator.
(b(ii))[3]
In the oxygenator, blood and oxygen-enriched air move in opposite directions. Suggest and explain how the oxygenator carries out the gas exchange functions that are normally performed by the lungs.
(c)[3]
Fig. 5.2 is a photomicrograph of a transverse section of part of the human aorta. Explain how the structure of the tunica media in Fig. 5.2 differs from the structure of the tunica media in a muscular artery and link the difference to the function of the aorta.
(d(i))[1]
Explain why the physiology of $C.\,latirostris$ needs carbonic anhydrase.
(d(ii))[1]
Explain why the physiology of $C.\,latirostris$ does not need the chloride shift.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Blood flow is shown correctly from right atrium through pump and back to vena cava” …