Theme

Level of Organization

1. Molecules

2. Cells

3. Organisms

4. Ecosystems

A

Unity and Diversity

Common ancestry has given living organisms many shared features while evolution has resulted in the rich biodiversity of life on Earth.

A1.1 Water

A1.2 Nucleic Acids

A2.1 Origins of cells [HL only]

A2.2 Cell structure 

A2.3 Viruses [HL only]

A3.1 Diversity of organisms

A3.2 Classification and cladistics [HL only]

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B

Form and Function

Adaptations are forms that correspond to function. These adaptations persist from generation to generation because they increase the chances of survival.

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes & membrane transport

B2.2 Organelles & compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B3.3 Muscle and motility [HL only]

B4.1 Adaptation to environment

B4.2 Ecological niches

C

Interaction and Interdependence

Systems are based on interactions, interdependence and integration of components. Systems result in emergence of new properties at each level of biological organization.

C1.1 Enzymes and metabolism

C1.2 Cell respiration

C1.3 Photosynthesis

C2.1 Chemical Signaling   [HL only]

C2.2 Neural Signaling

C3.1 Integration of body systems

C3.2 Defence against disease

C4.1 Populations and communities

C4.2 Transfers of energy and matter

D

Continuity and Change

Living things have mechanisms for maintaining equilibrium and for bringing about transformation. Environmental change is a driver of evolution by natural selection.

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutations & gene editing

D2.1 Cell and nuclear division

D2.2 Gene expression [HL only]

D2.3 Water potential

D3.1 Reproduction 

D3.2 Inheritance 

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Stability and change

D4.3 Climate change