Please write clearly in block capitals.
Centre number Candidate number
AS
Surname
Forename(s) BIOLOGY
Candidate signature
I declare this is my own work.
7401/2
Paper 2
AS
Mark scheme
BIOLOGY June 2026
Paper 2 Version: 1.0 Final
Thursday 21 May 2026 Morning Time allowed: 1 hour 30 minutes
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a ruler with millimetre measurements
• a scientific calculator. 1
2
Instructions
3
• Use black ink or black ball-point pen.
• Fill in the boxes at the top of this page. 4
• Answer all questions. 5
• You must answer the questions in the spaces provided. Do not write 6
outside the box around each page or on blank pages.
7
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s). 8
• Show all your working. 9
• Do all rough work in this book. Cross through any work you do not want
to be marked. TOTAL
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 75.
*jun *
IB/M/Jun26/G4003/V5 7401/2
, 2
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
Answer all questions in the spaces provided. box
Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
0 1 . 1 In the following passage, each numbered space can be filled with a biological term. standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
responses to questions and that every associate understands and applies it in the same correct way.
A gene is a sequence of bases in DNA that codes for the sequence of amino acids in As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
a polypeptide. A gene also codes for a functional (1) molecule. standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
A polypeptide folds into its secondary structure, held in place by (2) bonds
It must be stressed that a mark scheme is a working document, in many cases further developed and
which also occur in the tertiary structure. The tertiary structure of a protein can be expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
maintained by (3) bridges and (4) bonds. assessment remain constant, details will change, depending on the content of a particular examination
paper.
Write the correct biological term beside each number below so that it matches the
numbered space in the passage. No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
[2 marks] gender identity of others in their exam responses.
1 A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
2
3 Further copies of this mark scheme are available from
4
information
retains the on all its publications. However, registered schools/colleges for are permitted to copy material from this booklet for their own internal
use, with the following important exception: cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for
internal use within the centre.
and its licensors. All rights reserved.
*02*
2
IB/M/Jun26/7401/2
, 3
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
0 1 . 2 Enzymes are proteins that control the rate of reactions. box
Figure 1 shows the progress of a reaction without an enzyme. Mark scheme instructions to examiners
Figure 1
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
Draw a line on Figure 1 to show the progress of the same reaction with an enzyme. mark.
[2 marks]
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.
0 1 . 3 Formation of an enzyme-substrate complex increases the rate of reaction.
Explain how. 3. Marking points
[2 marks]
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.
6 However, responses considered to be neutral (often prefaced by ‘Ignore’ in the
‘Comments’ column of the mark scheme) are not penalised.
Turn over ►
*03*
3
IB/M/Jun26/7401/2
, 4
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
0 2 Cells from a garlic root can be used to observe mitosis. box
A student wrote a method for preparing a microscope slide of garlic root cells: 3.2 Marking procedure for calculations
Full marks can be given for a correct numerical answer, without any working shown.
1. Cut a section of garlic root and place it on a glass slide.
2. Add a drop of water to the slide. However, if the answer is incorrect, mark(s) can usually be gained by correct
3. Lay a cover slip on top of the section of root. substitution/working and this is shown in the ‘Comments’ column or by each stage of a
4. Observe the section of root under the microscope. longer calculation.
3.3 Interpretation of ‘it’
0 2 . 1 Suggest and explain two improvements to the method which are needed to obtain a
slide of cells suitable for observing mitosis. Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the
[4 marks] correct subject.
Improvement 1 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.
Explanation 1 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
Improvement 2
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.
Explanation 2
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.
*04*
4
IB/M/Jun26/7401/2
Centre number Candidate number
AS
Surname
Forename(s) BIOLOGY
Candidate signature
I declare this is my own work.
7401/2
Paper 2
AS
Mark scheme
BIOLOGY June 2026
Paper 2 Version: 1.0 Final
Thursday 21 May 2026 Morning Time allowed: 1 hour 30 minutes
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a ruler with millimetre measurements
• a scientific calculator. 1
2
Instructions
3
• Use black ink or black ball-point pen.
• Fill in the boxes at the top of this page. 4
• Answer all questions. 5
• You must answer the questions in the spaces provided. Do not write 6
outside the box around each page or on blank pages.
7
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s). 8
• Show all your working. 9
• Do all rough work in this book. Cross through any work you do not want
to be marked. TOTAL
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 75.
*jun *
IB/M/Jun26/G4003/V5 7401/2
, 2
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
Answer all questions in the spaces provided. box
Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
0 1 . 1 In the following passage, each numbered space can be filled with a biological term. standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
responses to questions and that every associate understands and applies it in the same correct way.
A gene is a sequence of bases in DNA that codes for the sequence of amino acids in As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
a polypeptide. A gene also codes for a functional (1) molecule. standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
A polypeptide folds into its secondary structure, held in place by (2) bonds
It must be stressed that a mark scheme is a working document, in many cases further developed and
which also occur in the tertiary structure. The tertiary structure of a protein can be expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
maintained by (3) bridges and (4) bonds. assessment remain constant, details will change, depending on the content of a particular examination
paper.
Write the correct biological term beside each number below so that it matches the
numbered space in the passage. No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
[2 marks] gender identity of others in their exam responses.
1 A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
2
3 Further copies of this mark scheme are available from
4
information
retains the on all its publications. However, registered schools/colleges for are permitted to copy material from this booklet for their own internal
use, with the following important exception: cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for
internal use within the centre.
and its licensors. All rights reserved.
*02*
2
IB/M/Jun26/7401/2
, 3
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
0 1 . 2 Enzymes are proteins that control the rate of reactions. box
Figure 1 shows the progress of a reaction without an enzyme. Mark scheme instructions to examiners
Figure 1
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
Draw a line on Figure 1 to show the progress of the same reaction with an enzyme. mark.
[2 marks]
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.
0 1 . 3 Formation of an enzyme-substrate complex increases the rate of reaction.
Explain how. 3. Marking points
[2 marks]
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.
6 However, responses considered to be neutral (often prefaced by ‘Ignore’ in the
‘Comments’ column of the mark scheme) are not penalised.
Turn over ►
*03*
3
IB/M/Jun26/7401/2
, 4
MARK SCHEME – AS BIOLOGY – 7401/2 – JUNE 2026
Do not write
outside the
0 2 Cells from a garlic root can be used to observe mitosis. box
A student wrote a method for preparing a microscope slide of garlic root cells: 3.2 Marking procedure for calculations
Full marks can be given for a correct numerical answer, without any working shown.
1. Cut a section of garlic root and place it on a glass slide.
2. Add a drop of water to the slide. However, if the answer is incorrect, mark(s) can usually be gained by correct
3. Lay a cover slip on top of the section of root. substitution/working and this is shown in the ‘Comments’ column or by each stage of a
4. Observe the section of root under the microscope. longer calculation.
3.3 Interpretation of ‘it’
0 2 . 1 Suggest and explain two improvements to the method which are needed to obtain a
slide of cells suitable for observing mitosis. Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the
[4 marks] correct subject.
Improvement 1 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.
Explanation 1 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
Improvement 2
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.
Explanation 2
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.
*04*
4
IB/M/Jun26/7401/2
