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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 A3.1: Diversity of Organisms 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 A3.1 Diversity of organisms. 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.

A3.1.1 Variation between organisms as a defining feature of life

A3.1.2 Species as groups of organisms with shared traits

A3.1.3 Binomial system for naming organisms

A3.1.4 Biological species concept

A3.1.5 Difficulties distinguishing between populations and species

A3.1.6 Diversity in chromosome numbers of plant and animal species

A3.1.7 Karyotyping and karyograms

A3.1.8 Unity and diversity of genomes within species

A3.1.9 Diversity of eukaryote genomes

A3.1.10 Comparison of genome sizes

A3.1.11 Current and potential future uses of whole genome sequencing

A3.1.12 Difficulties applying the biological species concept (HL)

A3.1.13 Chromosome number as a shared trait within a species (HL)

A3.1.14 Engagement with local plant or animal species to develop a dichotomous key (HL)

A3.1.15 Identification of species from environmental DNA in a habitat using barcodes (HL)

IB Biology Topic A3.1: Diversity of Organisms Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

IB Biology Topic A3.1: Diversity of Organisms Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

Lessons for A3.1 Diversity of organisms - IB

IB Biology Topic A3.1: Diversity of Organisms Lessons