Page 1 of 12
, Mark schemes
1
One mark for each correct row
3
(b) 16;
1
(c) 1. Higher affinity / loads more oxygen at low / same / high partial pressure / pO2;
2. (Therefore) oxygen moves from mother / to fetus;
2
(d) 1. Low affinity / oxygen dissociates;
Assume ‘it’ is adult haemoglobin
1. Accept: converse if ‘fetal haemoglobin’ is clearly stated
2. (Oxygen) to respiring tissues / muscles / cells;
2. Q: Neutral ‘respirate’
2
(e) Enough adult Hb produced / enough oxygen released / idea that curves / affinities /
Hb are similar / more red blood cells produced;
Neutral: ‘adult Hb is also produced’ as in the question stem
Reject: curves / affinities / Hb are the same
1
[9]
(a) High(er) affinity for oxygen / absorbs / loads more oxygen;
2
At lower partial pressure (of oxygen) / lower pO2;
Accept: Loads oxygen ‘quicker’, ‘more readily’, ‘higher saturation’,
use of figures from graph for first point.
Neutral: References to unloading.
2
Page 2 of 12
, Mark schemes
1
One mark for each correct row
3
(b) 16;
1
(c) 1. Higher affinity / loads more oxygen at low / same / high partial pressure / pO2;
2. (Therefore) oxygen moves from mother / to fetus;
2
(d) 1. Low affinity / oxygen dissociates;
Assume ‘it’ is adult haemoglobin
1. Accept: converse if ‘fetal haemoglobin’ is clearly stated
2. (Oxygen) to respiring tissues / muscles / cells;
2. Q: Neutral ‘respirate’
2
(e) Enough adult Hb produced / enough oxygen released / idea that curves / affinities /
Hb are similar / more red blood cells produced;
Neutral: ‘adult Hb is also produced’ as in the question stem
Reject: curves / affinities / Hb are the same
1
[9]
(a) High(er) affinity for oxygen / absorbs / loads more oxygen;
2
At lower partial pressure (of oxygen) / lower pO2;
Accept: Loads oxygen ‘quicker’, ‘more readily’, ‘higher saturation’,
use of figures from graph for first point.
Neutral: References to unloading.
2
Page 2 of 12
