Mark Scheme (Results)
January 2025
Pearson Edexcel International Advanced Level
In Biology (WBI15)
Paper 01 Respiration, Internal Environment,
Coordination, and Gene Technology
,Edexcel and BTEC Qualifications
Edexcel and BTEC qualifications are awarded by Pearson, the UK’s largest awarding body. We
provide a wide range of qualifications including academic, vocational, occupational and specific
programmes for employers. For further information visit our qualifications websites at
www.edexcel.com or www.btec.co.uk. Alternatively, you can get in touch with us using the
details on our contact us page at www.edexcel.com/contactus.
Pearson: helping people progress, everywhere
Pearson aspires to be the world’s leading learning company. Our aim is to help everyone
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 over 150 years,
and by working across 70 countries, in 100 languages, we have built an international reputation
for our commitment to high standards and raising achievement through innovation in
education. Find out more about how we can help you and your students at:
www.pearson.com/uk
January 2025
Question paper log number P78446A
Publications Code WBI15_01_2501_MS
All the material in this publication is copyright
© Pearson Education Ltd 2025
,General Marking Guidance
• 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 which marks will be awarded and exemplification may
be limited.
• When examiners are in doubt regarding the application of the mark
scheme to a 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
, Question Answer Additional guidance Mark
number
1(a)(i) An answer that includes the following points:
• correct peptide bond (1) (2)
• water molecule (1) ACCEPT the H going down from N
ACCEPT symbol or drawn e.g. H-0-H
Question Answer Additional guidance Mark
number
1(a)(ii)
A is the correct answer
(1)
B is not correct as decarboxylation does not join two amino
acids together it removes a carboxyl group
C is not correct as hydrolysis does not join two amino acids
together it is where water is used to break down chemical
bonds
D is not correct as phosphorylation does not join two amino
acids together it attaches a phosphate group to a molecule
January 2025
Pearson Edexcel International Advanced Level
In Biology (WBI15)
Paper 01 Respiration, Internal Environment,
Coordination, and Gene Technology
,Edexcel and BTEC Qualifications
Edexcel and BTEC qualifications are awarded by Pearson, the UK’s largest awarding body. We
provide a wide range of qualifications including academic, vocational, occupational and specific
programmes for employers. For further information visit our qualifications websites at
www.edexcel.com or www.btec.co.uk. Alternatively, you can get in touch with us using the
details on our contact us page at www.edexcel.com/contactus.
Pearson: helping people progress, everywhere
Pearson aspires to be the world’s leading learning company. Our aim is to help everyone
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 over 150 years,
and by working across 70 countries, in 100 languages, we have built an international reputation
for our commitment to high standards and raising achievement through innovation in
education. Find out more about how we can help you and your students at:
www.pearson.com/uk
January 2025
Question paper log number P78446A
Publications Code WBI15_01_2501_MS
All the material in this publication is copyright
© Pearson Education Ltd 2025
,General Marking Guidance
• 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 which marks will be awarded and exemplification may
be limited.
• When examiners are in doubt regarding the application of the mark
scheme to a 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
, Question Answer Additional guidance Mark
number
1(a)(i) An answer that includes the following points:
• correct peptide bond (1) (2)
• water molecule (1) ACCEPT the H going down from N
ACCEPT symbol or drawn e.g. H-0-H
Question Answer Additional guidance Mark
number
1(a)(ii)
A is the correct answer
(1)
B is not correct as decarboxylation does not join two amino
acids together it removes a carboxyl group
C is not correct as hydrolysis does not join two amino acids
together it is where water is used to break down chemical
bonds
D is not correct as phosphorylation does not join two amino
acids together it attaches a phosphate group to a molecule
