INTERNATIONAL AS
BIOLOGY (9610)
BL02
Unit 2 Biological Systems and Disease
Mark scheme
January 2023
Version: 1.0 Final
*231XBL02/MS*
, MARK SCHEME – INTERNATIONAL AS BIOLOGY – BL02 – JANUARY 2023
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
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.
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
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
It must be stressed that a mark scheme is a working document, in many cases further developed and
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
assessment remain constant, details will change, depending on the content of a particular examination
paper.
Further copies of this mark scheme are available from oxfordaqaexams.org.uk
Copyright information
OxfordAQA retains the copyright on all its publications. However, registered schools/colleges for OxfordAQA are permitted to copy material from this booklet for
their own internal use, with the following important exception: OxfordAQA cannot give permission to schools/colleges to photocopy any material that is
acknowledged to a third party even for internal use within the centre.
Copyright © 2023 Oxford International AQA Examinations and its licensors. All rights reserved.
2
, MARK SCHEME – INTERNATIONAL AS BIOLOGY – BL02 – JANUARY 2023
Question Marking guidance Mark Comments
01.1 Ser, Arg, Leu, Tyr; 1 All amino acids needed in the correct order
Question Marking guidance Mark Comments
01.2 1. Substitution of one base for another / described – eg 3rd triplet 2 1. Ignore reference to codons
change from G → C;
2. Still codes for same amino acid / for Leu; 2. Reject same amino acid formed or produced.
Question Marking guidance Mark Comments
01.3 1. Gly replaces Arg / change in amino acid (sequence)/primary 3
structure;
2. Change in hydrogen/ionic bonds 2. Reject peptide bonds
OR
Change in tertiary structure;
3. Substrate cannot fit/enter/bind/attach to active site
OR
Substrate is no longer a complementary shape to the
active site/no enzyme-substrate complexes form can form;
3
BIOLOGY (9610)
BL02
Unit 2 Biological Systems and Disease
Mark scheme
January 2023
Version: 1.0 Final
*231XBL02/MS*
, MARK SCHEME – INTERNATIONAL AS BIOLOGY – BL02 – JANUARY 2023
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
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.
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
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
It must be stressed that a mark scheme is a working document, in many cases further developed and
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
assessment remain constant, details will change, depending on the content of a particular examination
paper.
Further copies of this mark scheme are available from oxfordaqaexams.org.uk
Copyright information
OxfordAQA retains the copyright on all its publications. However, registered schools/colleges for OxfordAQA are permitted to copy material from this booklet for
their own internal use, with the following important exception: OxfordAQA cannot give permission to schools/colleges to photocopy any material that is
acknowledged to a third party even for internal use within the centre.
Copyright © 2023 Oxford International AQA Examinations and its licensors. All rights reserved.
2
, MARK SCHEME – INTERNATIONAL AS BIOLOGY – BL02 – JANUARY 2023
Question Marking guidance Mark Comments
01.1 Ser, Arg, Leu, Tyr; 1 All amino acids needed in the correct order
Question Marking guidance Mark Comments
01.2 1. Substitution of one base for another / described – eg 3rd triplet 2 1. Ignore reference to codons
change from G → C;
2. Still codes for same amino acid / for Leu; 2. Reject same amino acid formed or produced.
Question Marking guidance Mark Comments
01.3 1. Gly replaces Arg / change in amino acid (sequence)/primary 3
structure;
2. Change in hydrogen/ionic bonds 2. Reject peptide bonds
OR
Change in tertiary structure;
3. Substrate cannot fit/enter/bind/attach to active site
OR
Substrate is no longer a complementary shape to the
active site/no enzyme-substrate complexes form can form;
3
