Please check the examination details below before entering your candidate information
Candidate surname Other names
Centre Number Candidate Number
Edexcel Level 3 GCE
Thursday 4 June 2026
Mark Scheme (Results) Afternoon (Time: 2 hours) Paper
reference 9BN0/01
Biology A (Salters Nuffield)
Advanced
Summer 2026 PAPER 1: The Natural Environment and
Species Survival
You must have: Total Marks
Calculator, HB pencil, ruler
Instructions
Edexcel Advanced Level in Biology A •• Use black ink or ball-point pen.
Fill in the boxes at the top of this page with your name,
(Salters Nuffield) centre number and candidate number.
9BN0/01 •• Answer all questions.
Show all your working out in calculations and include units where appropriate.
• Answer the questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 100.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
•• You may use a scientific calculator.
In questions marked with an asterisk (*), marks will be awarded for your ability to
structure your answer logically showing how the points that you make are related
or follow on from each other where appropriate.
Advice
•• Read each question carefully before you start to answer it.
Try to answer every question.
• Check your answers if you have time at the end.
Turn over
P79058A Education Ltd.
P:1/1/1/1/1/1/1/1/1/1/1/
*P79058A0136*
,Edexcel and BTEC Qualifications Answer ALL questions. Write your answers in the spaces provided.
Some questions must be answered with a cross in a box . If you change your mind about an
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
answer, put a line through the box and then mark your new answer with a cross .
Edexcel and BTEC qualifications are awarded by the UK’s
largest awarding body. We provide a wide range of qualifications 1 Cystic fibrosis (CF) is a disorder caused by a mutation in the gene for the
CFTR protein.
including academic, vocational, occupational and specific
programmes for employers. For further information visit our (a) The number of nucleotide base pairs present in the non-mutated form of the
qualifications websites at or . gene is 189 000.
Alternatively, you can get in touch with us using the details on our (i) Which of the following could result in a gene mutation?
contact us page at
1. insertion of an extra base
2. removal of one base
3. removal of three bases
(1)
A 1 and 2 only
B 2 and 3 only
helping people progress, everywhere
C 1, 2 and 3
aspires to be the world’s leading learning company. Our aim is to help everyone
D none of them
progress in their lives through education. We believe in every kind of learning, for all
kinds of people, wherever they are in the world. We’ve been involved in education for
(ii) Which is the maximum number of amino acids that can be present in the
over 150 years, and by working across 70 countries, in 100 languages, we have built an
CFTR protein coded for by the non-mutated gene?
international reputation for our commitment to high standards and raising achievement (1)
through innovation in education. Find out more about how we can help you and your
A 62 999
students at:
B 63 000
C 186 000
D 566 991
Summer 2026
Question Paper Log Number P79058A
Publication Code 9BN0_01_2606_MS
All the material in this publication is
2
*P79058A0236*
,General Marking Guidance (iii) Explain how the genetic code determines the maximum number of amino
acids in this protein.
(2)
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
• All candidates must receive the same treatment. Examiners must mark the first
candidate in exactly the same way as they mark the last. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• Mark schemes should be applied positively. Candidates must be rewarded for what
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
they have shown they can do rather than penalised for omissions.
• Examiners should mark according to the mark scheme not according to their . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
perception of where the grade boundaries may lie.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• There is no ceiling on achievement. All marks on the mark scheme should be used
appropriately. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• All the marks on the mark scheme are designed to be awarded. Examiners should . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
always award full marks if deserved, i.e. if the answer matches the mark scheme.
Examiners should also be prepared to award zero marks if the candidate’s response
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
is not worthy of credit according to the mark scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• Where some judgement is required, mark schemes will provide the principles by
(b) People with cystic fibrosis produce thick mucus.
which marks will be awarded and exemplification may be limited.
• When examiners are in doubt regarding the application of the mark scheme to a Explain how this thick mucus makes the digestion of food difficult.
(3)
candidate’s response, the team leader must be consulted.
• Crossed out work should be marked UNLESS the candidate has replaced it with an . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
alternative response.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
(Total for Question 1 = 7 marks)
3
*P79058A0336* Turn over
, Question Answer Mark
Number
1(a)(i) The only correct answer is – C
A is incorrect because all the options could result in a mutation
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
B is incorrect because all the options could result in a mutation
D is incorrect because all the options could result in a mutation
(1)
Question Answer Mark
Number
1(a)(ii) The only correct answer is – A
B is incorrect because this has not considered the use of one triplet for a stop codon
C is incorrect because this has not considered the triplet code nature of the gene
D is incorrect because this has multiplied by 3 instead of dividing
(1)
Question Answer Additional guidance Mark
number
1(a)(iii) An explanation that makes reference to two of the following: IGNORE descriptions of degenerate code
• { triplet code / three bases / one codon } codes for one
amino acid (1)
BLANK PAGE
• (genetic code is) non overlapping (1)
• stop codons do not result in the addition of an amino acid ALLOW stop codons do not code for an
/ the first amino acid (met / methionine ) is often removed amino acid
(1) (2)
4
*P79058A0436*
Candidate surname Other names
Centre Number Candidate Number
Edexcel Level 3 GCE
Thursday 4 June 2026
Mark Scheme (Results) Afternoon (Time: 2 hours) Paper
reference 9BN0/01
Biology A (Salters Nuffield)
Advanced
Summer 2026 PAPER 1: The Natural Environment and
Species Survival
You must have: Total Marks
Calculator, HB pencil, ruler
Instructions
Edexcel Advanced Level in Biology A •• Use black ink or ball-point pen.
Fill in the boxes at the top of this page with your name,
(Salters Nuffield) centre number and candidate number.
9BN0/01 •• Answer all questions.
Show all your working out in calculations and include units where appropriate.
• Answer the questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 100.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
•• You may use a scientific calculator.
In questions marked with an asterisk (*), marks will be awarded for your ability to
structure your answer logically showing how the points that you make are related
or follow on from each other where appropriate.
Advice
•• Read each question carefully before you start to answer it.
Try to answer every question.
• Check your answers if you have time at the end.
Turn over
P79058A Education Ltd.
P:1/1/1/1/1/1/1/1/1/1/1/
*P79058A0136*
,Edexcel and BTEC Qualifications Answer ALL questions. Write your answers in the spaces provided.
Some questions must be answered with a cross in a box . If you change your mind about an
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
answer, put a line through the box and then mark your new answer with a cross .
Edexcel and BTEC qualifications are awarded by the UK’s
largest awarding body. We provide a wide range of qualifications 1 Cystic fibrosis (CF) is a disorder caused by a mutation in the gene for the
CFTR protein.
including academic, vocational, occupational and specific
programmes for employers. For further information visit our (a) The number of nucleotide base pairs present in the non-mutated form of the
qualifications websites at or . gene is 189 000.
Alternatively, you can get in touch with us using the details on our (i) Which of the following could result in a gene mutation?
contact us page at
1. insertion of an extra base
2. removal of one base
3. removal of three bases
(1)
A 1 and 2 only
B 2 and 3 only
helping people progress, everywhere
C 1, 2 and 3
aspires to be the world’s leading learning company. Our aim is to help everyone
D none of them
progress in their lives through education. We believe in every kind of learning, for all
kinds of people, wherever they are in the world. We’ve been involved in education for
(ii) Which is the maximum number of amino acids that can be present in the
over 150 years, and by working across 70 countries, in 100 languages, we have built an
CFTR protein coded for by the non-mutated gene?
international reputation for our commitment to high standards and raising achievement (1)
through innovation in education. Find out more about how we can help you and your
A 62 999
students at:
B 63 000
C 186 000
D 566 991
Summer 2026
Question Paper Log Number P79058A
Publication Code 9BN0_01_2606_MS
All the material in this publication is
2
*P79058A0236*
,General Marking Guidance (iii) Explain how the genetic code determines the maximum number of amino
acids in this protein.
(2)
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
• All candidates must receive the same treatment. Examiners must mark the first
candidate in exactly the same way as they mark the last. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• Mark schemes should be applied positively. Candidates must be rewarded for what
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
they have shown they can do rather than penalised for omissions.
• Examiners should mark according to the mark scheme not according to their . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
perception of where the grade boundaries may lie.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• There is no ceiling on achievement. All marks on the mark scheme should be used
appropriately. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• All the marks on the mark scheme are designed to be awarded. Examiners should . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
always award full marks if deserved, i.e. if the answer matches the mark scheme.
Examiners should also be prepared to award zero marks if the candidate’s response
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
is not worthy of credit according to the mark scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
• Where some judgement is required, mark schemes will provide the principles by
(b) People with cystic fibrosis produce thick mucus.
which marks will be awarded and exemplification may be limited.
• When examiners are in doubt regarding the application of the mark scheme to a Explain how this thick mucus makes the digestion of food difficult.
(3)
candidate’s response, the team leader must be consulted.
• Crossed out work should be marked UNLESS the candidate has replaced it with an . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
alternative response.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . ... . ... . ... . ... . ... . ... . ... . ... . ...
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(Total for Question 1 = 7 marks)
3
*P79058A0336* Turn over
, Question Answer Mark
Number
1(a)(i) The only correct answer is – C
A is incorrect because all the options could result in a mutation
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
B is incorrect because all the options could result in a mutation
D is incorrect because all the options could result in a mutation
(1)
Question Answer Mark
Number
1(a)(ii) The only correct answer is – A
B is incorrect because this has not considered the use of one triplet for a stop codon
C is incorrect because this has not considered the triplet code nature of the gene
D is incorrect because this has multiplied by 3 instead of dividing
(1)
Question Answer Additional guidance Mark
number
1(a)(iii) An explanation that makes reference to two of the following: IGNORE descriptions of degenerate code
• { triplet code / three bases / one codon } codes for one
amino acid (1)
BLANK PAGE
• (genetic code is) non overlapping (1)
• stop codons do not result in the addition of an amino acid ALLOW stop codons do not code for an
/ the first amino acid (met / methionine ) is often removed amino acid
(1) (2)
4
*P79058A0436*
