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.