Question Marking Guidance Mark Comments
01.1 1. Select at random;
2. Large sample/number (of snails)/>10; 2 1. Accept description of random
... [Show More] technique
2. Ignore ‘many’
01.2 Mean and standard deviation; 1 Accept 2 correct statistical values for 1 mark
Accept any order
Accept average for mean
Accept standard error for standard deviation
Accept interquartile range
01.3
(Littorina -) genus and
(littorea -) species; 1 Accept phonetic spelling
Accept genera
01.4 1. No (significant) difference between (mean) height (in these populations);
2. (Students) t-test; 2 Accept suitable null hypothesis
TOTAL 6
5
Question Marking Guidance Mark Comments
02.1
1. Condensation (reaction)/loss of water;
2. (Between) phosphate and deoxyribose;
3. (Catalysed by) DNA polymerase; 2 max 3. Reject if DNA polymerase joins AT/GC OR complementary nucleotides/bases OR forms hydrogen bonds
02.2 Correct answer for 2 marks = 70;; Accept for 1 mark,
A = 42 and T = 42
OR
420 (total bases in gene)
OR
210 (bases in template strand) 2
02.3 Histone; 1
02.4 1. DNA helicase;
2. Breaks hydrogen bonds between base pairs/ AT and GC/complementary bases
OR
Breaks hydrogen bonds between polynucleotide strands; 2
2. Reject hydrolysis of hydrogen bonds
TOTAL 7
6
Question Marking Guidance Mark Comments
03.1
1. Muscle contracts;
2. Constricts/narrows arteriole/lumen; 2 2. Accept decreases for constricts/narrows
2. Accept vasoconstriction for 1 mark
03.2
(Ventricles and arteries)
1. Ventricle (muscles) relaxed
OR
Arteries recoiled;
2. No (blood) backflow (into ventricles)
OR
No blood movement to/in/from arteries; (Atria and ventricles)
3. Atria (muscle) contracted;
4. Blood movement from atria (into ventricles); 4 Accept references to ventricle, artery or atrium (singular)
1. Accept no muscle activity
OR
Diastole
OR
Arteries smoothing blood flow
2. and 4. Accept flow/pumped for movement
03.3 Vena cava; 1
03.4 2 marks for correct answer = 130 (beats min−1);;
1 mark for correct stroke volume = 104 2
TOTAL 9
7
Question Marking Guidance Mark Comments
04.1
Measure temperature (in tube) at intervals and use appropriate corrective measure (if temperature has fluctuated); 1 Accept use thermometer/probe/ equivalent device for measure temperature
04.2 1. Length and diameter
OR
Surface area
OR
Volume
OR
Mass/weight (of cylinders);
2. Time in solution; 2 1. Ignore shape/size
2. Ignore ‘time’ if unqualified [Show Less]