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3.1.1
Monomers and Polymers
Analytical deep dive — question counts, mark distribution, mastery curves, command-word breakdowns, and examiner narrative analysis.
Questions
2
Total marks
8
Marks / Q
4.0
Accessibility
75.0%
Mastery
25.5%
Student strength
25.5%
01
At a glance
3.1.1 · Monomers and Polymers
8YRSYNTHESIS
3.1.1 (Monomers and Polymers) appeared in 2 of the 8 years between 2017 and 2024, contributing 2 questions and 8 marks across Papers 1, 2 and 3. KNOWLEDGE dominates the mark distribution at 100.0% of total marks. The accessibility–mastery gap sits at 49.5 percentage points (75.0% vs 25.5%) — most students reach partial credit, but full marks remain harder to secure. The largest single question observed is worth 5 marks, signalling that AQA expects complete hierarchical accounts in this sub-section. Mastery varied year-to-year, lowest in 2022 (13.0%) and highest in 2019 (38.0%).
Access–mastery gap
+50 pp
Lowest mastery
2022 · 13.0%
Highest mastery
2019 · 38.0%
02
Question type split
By marks · compound to dominant
8MARKS
8
marks
Knowledge100.0%8 marks
Application0.0%0 marks
Calculation0.0%0 marks
(by marks; compound rows assigned to dominant type):
03
Credit terms — quick reference
Mark scheme tier-locked
2TERMS
Tier 1 · Always credit
Tier 2 · Sometimes credit
polymer
Reject · Never credit
ester bond (for MP5); dimers/disaccharides/dipeptides as polymer examples; triglycerides (once)
04
Question patterns
Recurring formats & tariff structure
0PARAGRAPHS
05
Year-over-year presence
P1 + P3 · 2017–2024
8YEARS
| Year | Questions | Total marks | Mean accessibility | Mean mastery |
|---|---|---|---|---|
| 2017 | 0 | 0 | — COVID | — COVID |
| 2018 | 0 | 0 | — COVID | — COVID |
| 2019 | 1 | 5 | 80.0% | 38.0% |
| 2020 | 0 | 0 | — COVID | — COVID |
| 2021 | 0 | 0 | — COVID | — COVID |
| 2022 | 1 | 3 | 70.0% | 13.0% |
| 2023 | 0 | 0 | — COVID | — COVID |
| 2024 | 0 | 0 | — COVID | — COVID |
06
Mark scheme intelligence
2017–2024 mark scheme corpus
2TERMS
Tier 1 — frequently credited
| Term | Times credited | Years | Notes |
|---|---|---|---|
| polymer | 2 | 2019, 2022 |
Tier 2 — sometimes credited
| Term | Times credited | Years | Notes |
|---|---|---|---|
| ester bond (for MP5); dimers/disaccharides/dipeptides as polymer examples; triglycerides (once) | 1 | 2019 |
Marks in this sub-section are typically awarded for precise terminology and correct application of biological principles. Sequential mark schemes — where each mark requires building on the previous one — are common in multi-mark questions; stating the first step without progression rarely earns more than one mark. Calculation marks are typically split between method (correct setup and value extraction) and answer (accurate numerical result), allowing partial credit when arithmetic errors occur.
07
Where students lose marks
Examiner-anchored error patterns
1CASE STUDIES
Conceptual errors
- Disaccharides and dipeptides given as examples of polymers — the mark scheme requires structures containing many monomers; disaccharides and dipeptides contain only two, and this error was flagged as widespread in 2019 despite the question being one of the more successfully answered parts of Q10 (2019 P1 Q10.3)
- Bond formation or breakage not stated alongside the role of water — students correctly described water's role in condensation and hydrolysis but failed to articulate that condensation forms a bond and hydrolysis breaks one; both components are required for the mark points (2019 P1 Q10.3)
- Phospholipids not recognised as products of condensation reactions — the ester bond joining glycerol to fatty acids forms by condensation; in the 2022 table question, failing to tick the condensation row for phospholipid was a common source of lost marks (2022 P3 Q01.2)
Vocabulary errors
- "Ester bond" cited as the bond within a named polymer — rejected; glycosidic bonds link monosaccharides in polysaccharides, peptide bonds link amino acids in polypeptides, and phosphodiester bonds link nucleotides in polynucleotides; ester bonds apply to triglyceride synthesis and are not accepted as polymer bonds (2019 P1 Q10.3)
- Limited examiner data available for this category beyond the above.
Application errors
- Triglycerides cited as polymer examples — explicitly rejected at mark points 3 and 4; the question asked for polymers and their constituent monomers, and triglycerides are not polymers; this suggests students did not distinguish "biological macromolecule" from "polymer" (2019 P1 Q10.3)
- Condensation row in table not extended to phospholipids — students who correctly ticked condensation for DNA and proteins failed to apply the same logic to phospholipids; recognising that ester bond formation is also a condensation reaction was the specific discriminating step in 2022 P3 Q01.2
High-impact failures · examiner narrative
2022 P3 Q01.23 marks
Tested classification of biological molecules across three properties: contains peptide bonds, formed by condensation, and is a polymer. Only 13% scored all three marks, with 30.5% scoring zero. Row 1 (peptide bonds) was mostly correct; rows 2 and 3 discriminated severely. The failure concentrated on the condensation row: students correctly ticked condensation for DNA and proteins but missed the phospholipid, which is also a condensation product — the ester bond between glycerol and fatty acids forms with loss of water. The question exposed compartmentalised understanding of condensation: correctly applied to biopolymers but not extended to lipids.
08
Difficulty signals
Performance metric synthesis
50PP GAP
Mean accessibility
75.0%
Mean mastery
25.5%
Mean student strength
25.5%
The accessibility–mastery gap of 49.5 percentage points characterises this sub-section's difficulty profile. Most students reach partial credit; full marks remain harder to achieve. Within 3.1 (Biological molecules), 3.1.1 ranks 2 of 7 sub-sections by mean mastery (1 = hardest). Mean mastery was lowest in 2022 (13.0%) and highest in 2019 (38.0%).