Mark Scheme (Results)
2025 Predicted Paper
Pearson Edexcel Level 3 GCE
Edexcel AL Biology Marking Scheme 3B 2025 Predicted
PAPER 3 Advanced Level
1
, Edexcel AL Biology Marking Scheme 3B 2025 Predicted
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.
2
,Edexcel AL Biology Marking Scheme 3B 2025 Predicted
3
, Edexcel AL Biology Marking Scheme 3B 2025 Predicted
Comprehensive Mark Scheme
Question 1
(a) In photosynthesis, which molecule acts as the primary electron donor
in the light-dependent reactions? (1)
• Options:
a. NADP⁺
b. Water (H₂O)
c. Oxygen (O₂)
d. Glucose
Marking Scheme:
• Answer: b. Water (H₂O) (1 mark)
• Explanation: Water acts as the primary electron donor in the light-
dependent reactions of photosynthesis. During photolysis, water molecules
are split by the energy from sunlight, producing electrons, protons, and
oxygen. These electrons are transferred to photosystem II to replenish those
lost during the excitation process.
• Theory Needed: Students must understand the Z-scheme of photosynthesis,
photolysis, and the role of water in photosystems.
• Pattern Analysis (2015-2023): This type of question frequently appears
as a straightforward multiple-choice or short-answer question, testing basic
concepts of photosynthesis.
• How to Approach: Recall the process of the light-dependent reactions and
the origin of electrons used in photosystems.
• TLDR: Water is the source of electrons in the light-dependent reactions.
4
2025 Predicted Paper
Pearson Edexcel Level 3 GCE
Edexcel AL Biology Marking Scheme 3B 2025 Predicted
PAPER 3 Advanced Level
1
, Edexcel AL Biology Marking Scheme 3B 2025 Predicted
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.
2
,Edexcel AL Biology Marking Scheme 3B 2025 Predicted
3
, Edexcel AL Biology Marking Scheme 3B 2025 Predicted
Comprehensive Mark Scheme
Question 1
(a) In photosynthesis, which molecule acts as the primary electron donor
in the light-dependent reactions? (1)
• Options:
a. NADP⁺
b. Water (H₂O)
c. Oxygen (O₂)
d. Glucose
Marking Scheme:
• Answer: b. Water (H₂O) (1 mark)
• Explanation: Water acts as the primary electron donor in the light-
dependent reactions of photosynthesis. During photolysis, water molecules
are split by the energy from sunlight, producing electrons, protons, and
oxygen. These electrons are transferred to photosystem II to replenish those
lost during the excitation process.
• Theory Needed: Students must understand the Z-scheme of photosynthesis,
photolysis, and the role of water in photosystems.
• Pattern Analysis (2015-2023): This type of question frequently appears
as a straightforward multiple-choice or short-answer question, testing basic
concepts of photosynthesis.
• How to Approach: Recall the process of the light-dependent reactions and
the origin of electrons used in photosystems.
• TLDR: Water is the source of electrons in the light-dependent reactions.
4
