Transport in humans 29 a b and d are wrong because

Transport in humans
29. A
B and D are wrong because smooth muscle is used to maintain pressure not
to withstand it
C is wrong because endothelium is a one cell-thick layer so it does not help
withstand pressure
30. C
31. A
32. D
Remember that haem group has higher affinity for carbon monoxide and
hydrogen ions than oxygen
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Transport in humans
29. A
30. C
31. D
A is wrong because the dissociation curve is always sigmoid
B is wrong because when carbon dioxide increases, percentage saturation of
haemoglobin will decrease
32. D
As the valve opening is small, the left ventricle would have to push the blood
harder to deliver it to all body parts which causes the left ventricle to have
more muscle which prevents complete relaxation
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Transport in humans
27. B
3 is wrong because it happens in reverse H
2
CO
3
dissociates to H
+
and HCO
-
3
28. C
29. C
30. A
if the SAN was malfunctioning then also the atria would have a slower rate of
contraction so 3 is wrong
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Transport in humans
28. B
29. C
the defect would mix deoxygenated and oxygenated blood which decreases
oxygen saturation
30. A
Remember that carbaminohaemoglobin is not formed in the plasma but
inside RBC's
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Transport in humans
29. D
30. A
31. A
Remember that arteries' lumen is round while veins' lumen is oval
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Transport in humans
26. B
27. A
28. C
Repeated idea
29. D
The hole allow oxygenated and deoxygenated blood to mix, decreasing the
amount of oxygen reached to respiring tissues through the aorta
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Transport in humans
24. D
Remember that the pulmonary vein is the only vein that carries oxygenated
blood
25. C
26. C
Remember that carbonic anhydrase catalyses the reaction between carbon
dioxide and water producing carbonic acid which dissociates into hydrogen
ions and hydrogencarbonate ions
27. C
28. D
Remember that SAN is what starts the wave of excitation that causes atrial
systole
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Transport in humans
29. D
all three elements are present in the wall of arterioles; however, the question
asked about the one that would allow controlling the pressure, only muscles
can do that by changing the diameter
30. B
31. D
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Transport in humans
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282
Cell structure
Gaseous
exchange

Gaseous exchange
November 2002
29 - Not found in the new syllabus .
30- B
Lung volume is not effective in this case but the ventilation rate which is equal
to tidal volume x breathing rate.
31- B
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Gaseous exchange
June 2003
7-D
Measure the shortest distance between the cell surface of RBC and the inner
cell surface membrane of the epithelial cell of the alveolus divided by 5000.