ALEVELPAPERZZ2024
A-level
BIOLOGY
7402/3
Paper 3
Mark scheme
June 2024
Version: 1.0 Final
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Mark scheme instructions to examiners
1. General
The mark scheme for each question shows:
• the marks available for each part of the question
• the total marks available for the question
• the typical answer or answers which are expected
• extra information to help the examiner make his or her judgement and help to delineate what is
acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in
which a mark or marks may be awarded.
The extra information in the ‘Comments’ column is aligned to the appropriate answer in the left-
hand part of the mark scheme and should only be applied to that item in the mark scheme.
At the beginning of a part of a question a reminder may be given, for example: where
consequential marking needs to be considered in a calculation; or the answer may be on the
diagram or at a different place on the script.
In general the right-hand side of the mark scheme is there to provide those extra details which
confuse the main part of the mark scheme yet may be helpful in ensuring that marking is
straightforward and consistent.
2. Emboldening
2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is
used, with the number of marks emboldened. Each of the following bullet points is a
potential mark.
2.2 A bold and is used to indicate that both parts of the answer are required to award the
mark.
2.3 Alternative answers acceptable for the same mark are indicated by the use of OR.
Different terms in the mark scheme are shown by a / ; eg allow smooth / free movement.
3. Marking points
3.1 Marking of lists
This applies to questions requiring a set number of responses, but for which students
have provided extra responses. The general principle to be followed in such a situation is
that ‘right + wrong = wrong’.
Each error / contradiction negates each correct response. So, if the number of errors /
contradictions equals or exceeds the number of marks available for the question, no
marks can be awarded.
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the
‘Comments’ column of the mark scheme) are not penalised.
3
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
3.2 Marking procedure for calculations
Full marks can be given for a correct numerical answer, without any working shown.
However, if the answer is incorrect, mark(s) can usually be gained by correct substitution /
working and this is shown in the ‘Comments’ column or by each stage of a longer
calculation.
3.3 Interpretation of ‘it’
Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the
correct subject.
3.4 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are most likely to be restricted to calculation
questions and should be shown by the abbreviation ECF or consequential in the mark
scheme.
An arithmetic error should be penalised for one mark only unless otherwise amplified in
the mark scheme. Arithmetic errors may arise from a slip in a calculation or from an
incorrect transfer of a numerical value from data given in a question.
3.5 Phonetic spelling
The phonetic spelling of correct scientific terminology should be credited unless there is a
possible confusion with another technical term.
3.6 Brackets
(…..) are used to indicate information which is not essential for the mark to be awarded
but is included to help the examiner identify the sense of the answer required.
3.7 Ignore/Insufficient/Do not allow
Ignore or insufficient is used when the information given is irrelevant to the question or not
enough to gain the marking point. Any further correct amplification could gain the marking
point.
Do not allow means that this is a wrong answer which, even if the correct answer is
given, will still mean that the mark is not awarded.
4
,ALEVELPAPERZZ2024 MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Question Marking Guidance Mark Comments
1. (Cell-surface) membrane 6 correct = 3 marks
2. Protein 4–5 correct = 2 marks
3. Antigen 2–3 correct = 1 mark
4. Plasma 0–1 correct = 0 marks
5. Active 2. Accept immunoglobulin
3 max or glycoprotein
01.1 6. Herd;;; (3 x 2. Ignore tertiary
AO1) 2. Ignore polypeptide
3. Accept
complementary/specific
3. Ignore identical
5. Ignore artificial
5. Ignore primary
Question Marking Guidance Mark Comments
1. (High rate of) mutation; 1. Accept antigenic
variability OR
2. (High) genetic diversity; descriptions of
antigenic variability
3. HIV in cells could (still) spread infection;
4. HIV (DNA) embeds/inserts itself in host
DNA;
5. Lack of funding/money (for
research/development); 1 max
01.2 (1 x 6. Accept ‘HIV
6. HIV causes fewer T cells, so immune AO2) destroys/kills T cells’
response (to the vaccine) does not happen; for ‘HIV causes
reduced T cells’
6. Accept ‘so B cells not
activated’ for ‘so
immune response (to
the vaccine) does not
happen
6. Ignore immune cells
destroyed
5
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Question Marking Guidance Mark Comments
(Ciprofloxacin) 1. Ignore any
prefixes to RNA
1. (HIV) has RNA 1. Reject references
to single stranded
OR DNA
(HIV) does not have DNA;
(Penicillin) 2
01.3 (2 x
2. (HIV) has no cell wall AO2) 2. Reject any
references to
OR incorrect viral
structures, eg
(HIV) does not contain murein; viruses have a cell
membrane OR a
cell wall made of
chitin
6
A-level
BIOLOGY
7402/3
Paper 3
Mark scheme
June 2024
Version: 1.0 Final
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Mark scheme instructions to examiners
1. General
The mark scheme for each question shows:
• the marks available for each part of the question
• the total marks available for the question
• the typical answer or answers which are expected
• extra information to help the examiner make his or her judgement and help to delineate what is
acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in
which a mark or marks may be awarded.
The extra information in the ‘Comments’ column is aligned to the appropriate answer in the left-
hand part of the mark scheme and should only be applied to that item in the mark scheme.
At the beginning of a part of a question a reminder may be given, for example: where
consequential marking needs to be considered in a calculation; or the answer may be on the
diagram or at a different place on the script.
In general the right-hand side of the mark scheme is there to provide those extra details which
confuse the main part of the mark scheme yet may be helpful in ensuring that marking is
straightforward and consistent.
2. Emboldening
2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is
used, with the number of marks emboldened. Each of the following bullet points is a
potential mark.
2.2 A bold and is used to indicate that both parts of the answer are required to award the
mark.
2.3 Alternative answers acceptable for the same mark are indicated by the use of OR.
Different terms in the mark scheme are shown by a / ; eg allow smooth / free movement.
3. Marking points
3.1 Marking of lists
This applies to questions requiring a set number of responses, but for which students
have provided extra responses. The general principle to be followed in such a situation is
that ‘right + wrong = wrong’.
Each error / contradiction negates each correct response. So, if the number of errors /
contradictions equals or exceeds the number of marks available for the question, no
marks can be awarded.
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the
‘Comments’ column of the mark scheme) are not penalised.
3
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
3.2 Marking procedure for calculations
Full marks can be given for a correct numerical answer, without any working shown.
However, if the answer is incorrect, mark(s) can usually be gained by correct substitution /
working and this is shown in the ‘Comments’ column or by each stage of a longer
calculation.
3.3 Interpretation of ‘it’
Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the
correct subject.
3.4 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are most likely to be restricted to calculation
questions and should be shown by the abbreviation ECF or consequential in the mark
scheme.
An arithmetic error should be penalised for one mark only unless otherwise amplified in
the mark scheme. Arithmetic errors may arise from a slip in a calculation or from an
incorrect transfer of a numerical value from data given in a question.
3.5 Phonetic spelling
The phonetic spelling of correct scientific terminology should be credited unless there is a
possible confusion with another technical term.
3.6 Brackets
(…..) are used to indicate information which is not essential for the mark to be awarded
but is included to help the examiner identify the sense of the answer required.
3.7 Ignore/Insufficient/Do not allow
Ignore or insufficient is used when the information given is irrelevant to the question or not
enough to gain the marking point. Any further correct amplification could gain the marking
point.
Do not allow means that this is a wrong answer which, even if the correct answer is
given, will still mean that the mark is not awarded.
4
,ALEVELPAPERZZ2024 MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Question Marking Guidance Mark Comments
1. (Cell-surface) membrane 6 correct = 3 marks
2. Protein 4–5 correct = 2 marks
3. Antigen 2–3 correct = 1 mark
4. Plasma 0–1 correct = 0 marks
5. Active 2. Accept immunoglobulin
3 max or glycoprotein
01.1 6. Herd;;; (3 x 2. Ignore tertiary
AO1) 2. Ignore polypeptide
3. Accept
complementary/specific
3. Ignore identical
5. Ignore artificial
5. Ignore primary
Question Marking Guidance Mark Comments
1. (High rate of) mutation; 1. Accept antigenic
variability OR
2. (High) genetic diversity; descriptions of
antigenic variability
3. HIV in cells could (still) spread infection;
4. HIV (DNA) embeds/inserts itself in host
DNA;
5. Lack of funding/money (for
research/development); 1 max
01.2 (1 x 6. Accept ‘HIV
6. HIV causes fewer T cells, so immune AO2) destroys/kills T cells’
response (to the vaccine) does not happen; for ‘HIV causes
reduced T cells’
6. Accept ‘so B cells not
activated’ for ‘so
immune response (to
the vaccine) does not
happen
6. Ignore immune cells
destroyed
5
, MARK SCHEME – A-LEVEL BIOLOGY – 7402/3 – JUNE 2024
Question Marking Guidance Mark Comments
(Ciprofloxacin) 1. Ignore any
prefixes to RNA
1. (HIV) has RNA 1. Reject references
to single stranded
OR DNA
(HIV) does not have DNA;
(Penicillin) 2
01.3 (2 x
2. (HIV) has no cell wall AO2) 2. Reject any
references to
OR incorrect viral
structures, eg
(HIV) does not contain murein; viruses have a cell
membrane OR a
cell wall made of
chitin
6
