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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 A4.1.4: Evidence for Evolution from Homologous Structures Key Definitions

Definition

Analogous structures

Analogous structures are anatomical features in different species that serve similar functions but do not share a common evolutionary origin.

Definition

Homologous structures

Homologous structures are anatomical features that share a similar structure and position across different species but serve different functions.

Definition

Vestigial structure

A vestigial structure is a reduced anatomical feature that has lost its original function but is retained as an evolutionary remnant of a common ancestor.

IB Biology Topic A4.1.4: Evidence for Evolution from Homologous Structures Key Definitions

Definition

Analogous structures

Analogous structures are anatomical features in different species that serve similar functions but do not share a common evolutionary origin.

Definition

Homologous structures

Homologous structures are anatomical features that share a similar structure and position across different species but serve different functions.

Definition

Vestigial structure

A vestigial structure is a reduced anatomical feature that has lost its original function but is retained as an evolutionary remnant of a common ancestor.