Question Marking Guidance Mark Comments
1. (Reference to) hydrolysis of peptide bonds;
2. Endopeptidase act in the middle of protein/polypeptide
OR
Endopeptidase produces short(er) polypeptides/ increase number of
...
Question Marking Guidance Mark Comments
1. (Reference to) hydrolysis of peptide bonds;
2. Endopeptidase act in the middle of protein/polypeptide
OR
Endopeptidase produces short(er) polypeptides/ increase number of ends;
3. Exopeptidases act at end of protein/polypeptide
OR
Exopeptidase produces dipeptides/amino acids;
4. Dipeptidase acts on dipeptide/between two amino acids
OR
Dipeptidase produces (single) amino acids; 4 Accept chain/chain of amino acids/peptide for polypeptide
Accept digest/breakdown/ break for ‘act’
01.1 Mark points 2, 3 and 4 reject answers where substrate or product is incorrect eg ‘Endopeptidase produces dipeptides’
Ignore references to source and location of enzymes
1. No significant difference (in protein absorption);
2. (because ± 2) SDs overlap;
3. (So mean) percentage absorbed not affected by percentage in diet;
4. Amount of protein (in diet) is not a limiting factor
OR
Something else is limiting factor eg amount of protease;
5. (But) small range of protein in diet
OR
(Should) Investigate wider range; 3 max Ignore reference to ‘significance’ unless qualified, eg ‘difference’
01.2 2. Accept error bar for SD
01.3 1. More/remaining/undigested (protein) broken down;
2. (So more) amino acids absorbed;
3. (Because) protein/food passes again through stomach/ileum; 3 1. Accept all (protein) broken down
TOTAL 10
Question Marking Guidance Mark Comments
02.1
1. Increases/more oxygen dissociation/unloading
OR
Deceases haemoglobin’s affinity for O2;
2. (By) decreasing (blood) pH/increasing acidity; 2 1. Accept more readily
1. Accept releases more O2
2. Reject if reference made to active site
1. High(er) affinity for O2 (than haemoglobin)
OR 2 1. Accept holds O2 at lower ppO2
Dissociates oxygen less readily
OR
Associates more readily;
02.2 2. Allows (aerobic) respiration when diving/at 2. Accept acts as an
low(er) pO2
OR oxygen store
Provides oxygen when haemoglobin unloaded
OR
Delays anaerobic respiration/lactate production;
02.3 Correct answer for 2 marks
10.8 to 11 (mins)
OR
10 minutes and 48 seconds = 2 marks;;
Accept for 1 mark,
10.48 minutes
OR
Reference to 2057.7 to 2058 (10 700 ÷ 5.2, time oxygen would last if its mass was 1 kg)
OR
Reference to 56 to 56.3 (10700 ÷ 190, oxygen in 1 kg of seal)
OR
Reference to 988 (5.2 x 190, oxygen used min-1 by the seal)
OR
Incorrect answer with correct answer shown in working 2
..................................................................CONTINUED................................................
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