A-LEVEL BIOLOGY MARK SCHEME
Practice Paper 2 Maximum marks: 91
View detailed guidance on the conclusions you can draw from your students' performance in
these papers on the MERiT welcome page. Understand how your students compare with
others and target revision effectively by entering marks into MERiT.
1 (a) Prevents oxygen being taken up / entering / being absorbed; 1
Accept: any idea of no contact with oxygen.
Neutral: for anaerobic respiration / anaerobic conditions.
Neutral: prevents entry of air.
Reject: prevents entry of oxygen and another named gas.
(b) (i) 0..016 = 2 marks;; 2
0....08 = 1 mark
/ 0.62 = 1 mark
(ii) Glucose decreases / is a limiting factor / increase in ethanol / yeast / 1
cells die / toxins build up;
Accept: glucose is used up.
(iii) 1. (Stays the) same / level / (relatively) constant; 2
2. Same volume / amount of oxygen uptake and carbon dioxide release;
Note: if m.p.1 is awarded m.p 2 can be obtained without
referring to ‘same volume / amount’.
(c) 1. Oxygen is final / terminal (electron) acceptor / oxygen combines 2
with electrons and protons;
2. Oxidative phosphorylation / electron transport chain provides (most) ATP
/ only glycolysis occurs without oxygen / no Krebs / no link reaction;
[Total 8 marks]
2 (a) 1. (In myelinated) action potential / depolarisation only at node(s); 3
2. (In myelinated, nerve impulse) jumps from node to node / saltatory;
3. (In myelinated) action potential / impulse does not travel along whole length;
The question is about speed of transmission, not repolarisation
or related matters
Accept converse for non-myelinated
(b) 1. Probability of obtaining this difference by chance; 2 max
Reject ‘results’ once only/ This statement often split round 2.
2. Is less than 5% / less than 0.05 / less than one in twenty;
Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047
Accept correct greater than 95% / greater than 0.95 arguments
3. Difference is significant;
1 max for 'the probability that the results are due to chance is
less than 5%'
This document is licensed to Haggerston School - MB260045
, (c) 1. (All) dementia results lower (than control group) / 4 max
non-dementia result higher;
2. No overlap in SDs so differences are (possibly) significant;
Neutral results
Accept not due to chance / statistically significant
In this context, accept references to standard deviation
3. Dementia may be due to other factors / not only due to a lack of myelin;
Accept suitable named factor e.g. genetic
4. (Because) big / significant differences in myelin in different dementia;
Not just ‘different’
5. Only small sample sizes / only one study / more data required;
[Total 9 marks]
3 (a) 1. Causes sodium ion channels to open; 2
1. Reject if wrong sequence of events
2. Sodium ions enter (cell and cause depolarisation);
Reject sodium on its own only once
(b) 1. (If not removed) keeps binding (to receptors); 2
Accept answers as should happen
2. Keeps causing action potentials / depolarisation (in post-synaptic membrane);
2. Accept keeps Na + channels open(ing)
(c) 1. Movement in all groups (about) same before MDMA; 3 max
2. MDMA increases movement in Group L;
2. Accept normal mice for L
3. Group K shows MDMA causes movement;
3. Accept K is a control
4. No / little increase in mice without receptor / Group M;
[Total 7 marks]
4 (a) Treatment requires person receiving insulin (in some way); 1
Accept descriptions e.g. insulin injection
Reward idea that insulin must be received, not that it isn’t being
produced
(b) 1. No / fewer / abnormal receptors on (cell) membrane; 3 max
2. (So) fewer (glucose) transport proteins;
3. (So) no glucose can enter (cells);
4. (So) less glucose converted to glycogen;
Accept no / fewer enzymes (for this conversion) are activated
5. (So, without treatment) blood glucose concentration not lowered when
high / above normal;
Accept converse
(c) 1. Movement uses muscles; 2 max
2. Movement increases (rate of) respiration;
3. Respiration uses glucose / respiration reduces blood glucose concentration;
This document is licensed to Haggerston School - MB260045
Practice Paper 2 Maximum marks: 91
View detailed guidance on the conclusions you can draw from your students' performance in
these papers on the MERiT welcome page. Understand how your students compare with
others and target revision effectively by entering marks into MERiT.
1 (a) Prevents oxygen being taken up / entering / being absorbed; 1
Accept: any idea of no contact with oxygen.
Neutral: for anaerobic respiration / anaerobic conditions.
Neutral: prevents entry of air.
Reject: prevents entry of oxygen and another named gas.
(b) (i) 0..016 = 2 marks;; 2
0....08 = 1 mark
/ 0.62 = 1 mark
(ii) Glucose decreases / is a limiting factor / increase in ethanol / yeast / 1
cells die / toxins build up;
Accept: glucose is used up.
(iii) 1. (Stays the) same / level / (relatively) constant; 2
2. Same volume / amount of oxygen uptake and carbon dioxide release;
Note: if m.p.1 is awarded m.p 2 can be obtained without
referring to ‘same volume / amount’.
(c) 1. Oxygen is final / terminal (electron) acceptor / oxygen combines 2
with electrons and protons;
2. Oxidative phosphorylation / electron transport chain provides (most) ATP
/ only glycolysis occurs without oxygen / no Krebs / no link reaction;
[Total 8 marks]
2 (a) 1. (In myelinated) action potential / depolarisation only at node(s); 3
2. (In myelinated, nerve impulse) jumps from node to node / saltatory;
3. (In myelinated) action potential / impulse does not travel along whole length;
The question is about speed of transmission, not repolarisation
or related matters
Accept converse for non-myelinated
(b) 1. Probability of obtaining this difference by chance; 2 max
Reject ‘results’ once only/ This statement often split round 2.
2. Is less than 5% / less than 0.05 / less than one in twenty;
Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047
Accept correct greater than 95% / greater than 0.95 arguments
3. Difference is significant;
1 max for 'the probability that the results are due to chance is
less than 5%'
This document is licensed to Haggerston School - MB260045
, (c) 1. (All) dementia results lower (than control group) / 4 max
non-dementia result higher;
2. No overlap in SDs so differences are (possibly) significant;
Neutral results
Accept not due to chance / statistically significant
In this context, accept references to standard deviation
3. Dementia may be due to other factors / not only due to a lack of myelin;
Accept suitable named factor e.g. genetic
4. (Because) big / significant differences in myelin in different dementia;
Not just ‘different’
5. Only small sample sizes / only one study / more data required;
[Total 9 marks]
3 (a) 1. Causes sodium ion channels to open; 2
1. Reject if wrong sequence of events
2. Sodium ions enter (cell and cause depolarisation);
Reject sodium on its own only once
(b) 1. (If not removed) keeps binding (to receptors); 2
Accept answers as should happen
2. Keeps causing action potentials / depolarisation (in post-synaptic membrane);
2. Accept keeps Na + channels open(ing)
(c) 1. Movement in all groups (about) same before MDMA; 3 max
2. MDMA increases movement in Group L;
2. Accept normal mice for L
3. Group K shows MDMA causes movement;
3. Accept K is a control
4. No / little increase in mice without receptor / Group M;
[Total 7 marks]
4 (a) Treatment requires person receiving insulin (in some way); 1
Accept descriptions e.g. insulin injection
Reward idea that insulin must be received, not that it isn’t being
produced
(b) 1. No / fewer / abnormal receptors on (cell) membrane; 3 max
2. (So) fewer (glucose) transport proteins;
3. (So) no glucose can enter (cells);
4. (So) less glucose converted to glycogen;
Accept no / fewer enzymes (for this conversion) are activated
5. (So, without treatment) blood glucose concentration not lowered when
high / above normal;
Accept converse
(c) 1. Movement uses muscles; 2 max
2. Movement increases (rate of) respiration;
3. Respiration uses glucose / respiration reduces blood glucose concentration;
This document is licensed to Haggerston School - MB260045
