BIOLOGY · Pearson Edexcel IGCSE
BIOLOGY/21
B / 2BR (Advanced Biology)
Biology · 2023 · Variant 1
Relative difficulty
Analysis source: Pearson Edexcel
Analysis aligned to the official syllabus and assessment design.
3.5 / 5
180
195 min
Structure and functions in living organisms (Transport and Gas Exchange)
Cohort performance
Session statistics from official examination reports
Total marks
180
Duration
195 min
Session difficulty
3.5 / 5
Key examiner messages
Top priorities from the principal examiner before you revise
In Paper 1B, high-scoring students secured easy marks on standard cell structure identification and genetic diagrams.
However, significant marks were lost in the osmosis and practical methodology sections.
Many struggled to explain the cellular impacts of water potential changes on red blood cells, frequently using incorrect terms like 'plasmolysed' (which is restricted to plant cells) instead of crenated or shrivelled.
In Paper 2B, the longer 5-mark evaluation on contraception and the 4-mark natural selection discussion on bioluminescence proved challenging.
Question difficulty map
How candidates performed on each question in this series
No data available in official reports
Assessment objectives
Skill and AO weighting from official examiner commentary
Skill weighting
Shows the skill mix this paper tested most heavily.
Recall & Understanding
Weight: 5100%Biological Experimental
Weight: 480%Interpretation
Weight: 240%Mathematical & Calculation
Weight: 120%
Method marks watchlist
Where working, steps, or method marks were commonly lost
Method marks
In calculation questions, failing to show step-by-step intermediate working. If the final numerical answer is incorrect, students lose all process marks that could have been saved with visible working.
Recurring mistakes across years
Themes examiners flag in multiple recent sessions for this subject
No data available in official reports
Question choice intelligence
Mean scores and popularity for optional questions (HKDSE electives)
No data available in official reports
Level exemplars
What candidate scripts at each grade level looked like
No data available in official reports
Grade & admission context
How marks relate to grade thresholds and entry standards
Report type
Examiner report — national grade boundaries and question-level commentary
Level 9
Approx. 81% of maximum mark
Level 8
Approx. 70% of maximum mark
Level 7
Approx. 59% of maximum mark
Level 6
Approx. 52% of maximum mark
Level 5
Approx. 44% of maximum mark
Level 4
Approx. 37% of maximum mark
Level 3
Approx. 31% of maximum mark
Level 2
Approx. 24% of maximum mark
Deep insights
What top candidates did
Techniques and approaches examiners rewarded in this series
No data available in official reports
Command word playbook
How to match each command word to the expected response style
Give reasons and link mechanism to outcome; each point needs a because/so chain.
State features in sequence or list observable properties — do not explain causes unless asked.
Show formula, substitution, and unit; method marks need visible working.
Match the expected response style for “State” questions.
Present multiple perspectives with evidence; balance breadth and depth.
Time traps
Sections where candidates spent disproportionate time relative to marks
Min per mark: 1.1
Min per mark: 1.1
Min per mark: 1.1
Syllabus traceability
Topics linked to questions and mark weighting in this session
Transport
24 marks this session
Inheritance
20 marks this session
Biological molecules
15 marks this session
Gas exchange
15 marks this session
MCQ trap analytics
Commonly chosen wrong options from examiner commentary
No data available in official reports
Topic heatmap across years
Mark concentration by topic and exam year for this subject
Mark intensity
Reproduction
Nutrition (Structure and functions in living organisms)
The organism in the environment
Reproduction (Reproduction and inheritance)
Transport
Transport (Structure and functions in living organisms)
Inheritance
Biological molecules
Difficulty trend
How session difficulty has shifted across recent years
Paper comparison
Marks and duration breakdown across papers in this session
Paper 1B:
Paper 2B:
Marks you can still earn
Where valid approaches outside the mark scheme may still gain credit
No data available in official reports
Practise what examiners flagged
Target weak topics from this report inside the Revui app
Transport
24 marks this session
Practise in RevuiInheritance
20 marks this session
Practise in RevuiBiological molecules
15 marks this session
Practise in RevuiGas exchange
15 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
In Paper 1B, high-scoring students secured easy marks on standard cell structure identification and genetic diagrams.
- 2Message
However, significant marks were lost in the osmosis and practical methodology sections.
- 3Message
Many struggled to explain the cellular impacts of water potential changes on red blood cells, frequently using incorrect terms like 'plasmolysed' (which is restricted to plant cells) instead of crenated or shrivelled.
- 4Message
In Paper 2B, the longer 5-mark evaluation on contraception and the 4-mark natural selection discussion on bioluminescence proved challenging.
- 5Method
In calculation questions, failing to show step-by-step intermediate working. If the final numerical answer is incorrect, students lose all process marks that co
Teacher briefing pack
One-page session summary for tutors and classroom review
2023 2023
Biology
In Paper 1B, high-scoring students secured easy marks on standard cell structure identification and genetic diagrams. However, significant marks were lost in the osmosis and practical methodology sections. Many struggled to explain the cellular impacts of water potential changes
In Paper 1B, high-scoring students secured easy marks on standard cell structure identification and genetic diagrams.
However, significant marks were lost in the osmosis and practical methodology sections.
Many struggled to explain the cellular impacts of water potential changes on red blood cells, frequently using incorrect terms like 'plasmolysed' (which is restricted to plant cells) instead of crenated or shrivelled.
- Total marks
- 180
- Duration
- 195 min
- Session difficulty
- 3.5 / 5
Session analysis
In Paper 1B, high-scoring students secured easy marks on standard cell structure identification and genetic diagrams. However, significant marks were lost in the osmosis and practical methodology sections. Many struggled to explain the cellular impacts of water potential changes on red blood cells, frequently using incorrect terms like 'plasmolysed' (which is restricted to plant cells) instead of crenated or shrivelled. In Paper 2B, the longer 5-mark evaluation on contraception and the 4-mark natural selection discussion on bioluminescence proved challenging. Candidates often failed to provide the necessary depth, choosing to write superficial statements rather than comparing specific parameters like efficacy, ease of use, or the requirement of clinical procedures.
Updated Jun 13, 2026
Paper breakdown
Paper 1B:
Paper 2B:
Top chapters
Exam structure insights
Marks by chapter
See where the marks were concentrated so revision time goes to the highest-value topics.
Mark accessibility
Estimate which marks were basic, mid-level, or high-difficulty.
75% within easy or medium reach
Command word frequency
Spot common command words so answers match the expected response style.
Question type mix
Compare the mark share of each paper section and question type.
Short Answer
(1-3 marks)
65·30·36%
Structured Explanation
65·15·36%
Extended / Experimental Write-up
40·8·22%
Multiple Choice
10·10·6%
Study ROI
Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.
Time vs marks
Compare marks with suggested time allocation to plan exam pacing.
Paper 1B Questions …
0.89 m/minPaper 1B Questions …
0.94 m/minPaper 2B Questions …
0.93 m/minTotal marks
119
Total time
130 min
Avg pace
0.92
Next-year prediction
Topics worth watching next year, with the reason shown directly below each bar.
Respiration (cellular, aerobic & anaerobic differences)
5%5%
Plant reproduction & Pollination
4%4%
The Carbon Cycle & Greenhouse Gases
4%4%
Examiner notes & key calculations
- Command Word Confusion: Many candidates described trends where they were explicitly asked to explain them, resulting in zero marks for those sections.
- Vague Scientific Terminology: Using broad terms like 'nutrients' instead of specifying 'nitrates' or 'magnesium' frequently led to lost marks.
- Calculation Errors: Failing to convert units correctly (e.g., μm \mu\text{m} μm to mm \text{mm} mm) and not displaying intermediate steps resulted in a loss of process marks.
- Photosynthesis vs. Respiration Misconceptions: A recurring examiner comment highlighted that many students incorrectly believe plants only begin to respire when it becomes dark. Respiration is a continuous, life-sustaining process occurring in both light and dark conditions.
Exam tips
Paper format
- Duration
- 1h 15min
- Total marks
- 70
- Weighting
- 38.9%
- Question types
- Comprehension Passage, Structured and Short Answer, Practical / Experimental Design, Mathematical / Calculation
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.