bio letters

IB biology notes

LAST UPDATED: 31st March, 2026
11 topic notes left to go
topic notes should be done before May 2026 exams – sorry for not responding to your emails! I’m trying to balance this with my university finals so I hope to get around to writing these notes very soon

Question Bank

A4.1 Paper 1A
[MARKSCHEME]

B2.3 Paper 1A
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B1.1 Paper 1A
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C4.1 Paper 1A
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C4.2 Paper 1A
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C4.2 Paper 2
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Notes

A1.1 Water

A1.2 Nucleic acids

A2.2 Cell Structure

NEW

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.3 Muscle and motility

B4.1 Adaptation to environment

B4.2 Ecological niches

C1.1 Enzymes and metabolism
C1.2 Cell respiration
C1.3 Photosynthesis
C2.1 Chemical signalling
C2.2 Neural signalling
C3.1 Integration of body systems

[UPDATED]

C3.2 Defence against disease
C4.1 Populations and communities

C4.2 Transfer of energy and matter

D1.1 DNA replication
D1.2 Protein synthesis

D1.3 Mutation and gene editing

D2.2 Gene expression
D3.1 Reproduction
D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection