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A1.1 Water

A1.2 Nucleic acids

A2.1 Origins of cells (HL)

A2.2 Cell structure

A2.3 Viruses (HL)

A3.1 Diversity of organisms

A3.2 Classification and cladistics (HL)

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes and membrane transport

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B3.3 Muscle and motility (HL)

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 (HL)

C2.2 Neural signalling

C3.1 Integration of body systems

C3.2 Defense against disease

C4.1 Populations and communities

C4.2 Transfer of energy and matter

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutations and gene editing

D2.1 Cell and nuclear division

D2.2 Gene expression (HL)

D2.3 Water potential

D3.1 Reproduction

D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Sustainability and change

D4.3 Climate change

IB Biology Topic A3.2: Classification and Cladistics Lessons

Written by IB Experts

This lesson delivers structured, step-by-step lessons that guide students through every part of the IB Biology syllabus for A3.2 Classification and cladistics (HL). These lessons simplify complex ideas like molecular biology, evolutionary mechanisms, and homeostasis, while worked examples show how to approach IB-style questions.

Designed for both HL and SL learners, RevisionDojo lessons ensure students not only understand the theory but also know how to apply it in IB Paper exam situations.

With clear explanations, active learning checks, and a syllabus-first design, RevisionDojo makes revision less overwhelming and more effective.

A3.2.1 Need for classification of organisms (HL)

A3.2.2 Difficulties classifying organisms into the traditional hierarchy of taxa (HL)

A3.2.3 Advantages of classification corresponding to evolutionary relationships (HL)

A3.2.4 Clades as groups of organisms with common ancestry and shared characteristics (HL)

A3.2.5 Gradual accumulation of sequence differences (HL)

A3.2.6 Base sequences of genes or amino acid sequences of proteins (HL)

A3.2.7 Analysing cladograms (HL)

A3.2.8 Using cladistics to investigate evolutionary relationships (HL)

A3.2.9 Classification of all organisms using evidence from rRNA base sequences (HL)

IB Biology Topic A3.2: Classification and Cladistics Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

IB Biology Topic A3.2: Classification and Cladistics Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

Lessons for A3.2 Classification and cladistics (HL) - IB

IB Biology Topic A3.2: Classification and Cladistics Lessons