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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 A4.1: Evolution and Speciation 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 A4.1 Evolution and speciation. 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.

A4.1.1 Evolution as change in the heritable characteristics of a population

A4.1.2 Evidence for evolution from base sequences in DNA or RNA and amino acid sequences

A4.1.3 Evidence for evolution from selective breeding of domesticated animals and crop plants

A4.1.4 Evidence for evolution from homologous structures

A4.1.5 Convergent evolution as the origin of analogous structures

A4.1.6 Speciation by splitting of pre-existing species

A4.1.7 Roles of reproductive isolation and differential selection in speciation

A4.1.8 Differences and similarities between sympatric and allopatric speciation (HL)

A4.1.9 Adaptive radiation as a source of biodiversity (HL)

A4.1.10 Barriers to hybridization and sterility of interspecific hybrids (HL)

A4.1.11 Abrupt speciation in plants by hybridization and polyploidy (HL)

IB Biology Topic A4.1: Evolution and Speciation Lessons

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

A - Unity and Diversity

B - Form and Function

C - Interaction and Interdependence

D - Continuity and Change

IB Biology Topic A4.1: Evolution and Speciation Lessons

Lessons for A4.1 Evolution and speciation - IB

IB Biology Topic A4.1: Evolution and Speciation Lessons