What IAL Biology Units 1–3 actually test
1857 question parts across 3 papers — 4200 marks — classified by topic. Revise in this order.
Unit 1 in two minutes — the topics that come up every series.
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Unit 1: Molecules, Diet, Transport and Health (WBI11/01)
20 papers · 733 question parts · 1600 marks
- Cardiovascular disease and its treatment 20.1%
- Genetics 17.0%
- The heart and circulation 10.3%
- Haemoglobin and blood clotting 10.1%
- Water and carbohydrates 8.4%
- Lipids and proteins 7.4%
- Movement across the membrane 6.1%
- Biological membranes 5.9%
Cardiovascular disease and its treatment, Genetics and The heart and circulation carry 47% of the marks.
Unit 2: Cells, Development, Biodiversity and Conservation (WBI12/01)
20 papers · 741 question parts · 1312 marks
- Meiosis & fertilisation 21.0%
- Plant tissues 20.3%
- Cells & protein trafficking 15.9%
- Mitosis 8.8%
- Variation & biodiversity 8.1%
- Drug testing 7.6%
- Conservation 6.2%
- Classification 4.8%
Meiosis & fertilisation, Plant tissues and Cells & protein trafficking carry 57% of the marks.
Unit 3: Practical Skills in Biology I (WBI13/01)
20 papers · 383 question parts
Practical-skills paper — questions are not tied to chapters. Most common command words: Describe (71), Explain (58), Calculate (50), State (33). 25% of parts are high-difficulty.
Command words, most to least common
Explain (409), Calculate (213), Describe (206), Multiple choice (154), Suggest (135), State (110).
"Explain" and "Describe" questions are where marks are lost — the answer is right but not in mark-scheme words. Every question in the solved papers is written in those words.
About this analysis. Mr Hosni's team classified every question part of Unit 1: Molecules, Diet, Transport and Health (WBI11/01) (20 papers, 733 parts); Unit 2: Cells, Development, Biodiversity and Conservation (WBI12/01) (20 papers, 741 parts); Unit 3: Practical Skills in Biology I (WBI13/01) (20 papers, 383 parts) by topic, command word and difficulty. Percentages are shares of the marks available across all papers. The same classification drives the By-Topic mode of the Chem Bio solved-papers plugin, where each question opens to a full model answer. Updated after each new series.
