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Date November 2010 Marks available 6 Reference code 10N.3.HL.TZ0.15
Level Higher level Paper Paper 3 Time zone TZ0
Command term Explain Question number 15 Adapted from N/A

Question

Explain the oxygen dissociation curves of adult hemoglobin, fetal hemoglobin and myoglobin.

Markscheme

adult hemoglobin: [2 max]

a. rapid saturation of oxygen in the lungs;

b. rapid dissociation of oxygen as the oxygen concentration decreases;

c. oxygen released in the tissues where needed;

fetal hemoglobin: [2 max]

d. fetal hemoglobin curve to the left of adult hemoglobin;

e. higher affinity for oxygen than adult hemoglobin;

f. oxygen moves from adult hemoglobin to fetal hemoglobin;

myoglobin: [2 max]

g. myoglobin to the left of fetal hemoglobin;

h. higher affinity for oxygen than adult hemoglobin;

i. only releases oxygen at very low oxygen concentrations/in tissues;

j. oxygen reserve;

Examiners report

There were some very complete answers and some very weak ones. Many talked about Bohr shift instead of explaining the graphs.

Syllabus sections

Option D: Human physiology » Option D: Human physiology (Additional higher level topics) » D.6 Transport of respiratory gases
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