IB Biology Syllabus 2025

The IB Biology syllabus is a list of all the content standards, skill applications and nature of science standards that the IB Organization mandates are taught throughout the two years of the IB Biology higher level course.   The full syllabus can be seen here.  While SHS does not necessarily progress through the content statements in order, they are presented in order here.  If you are curious about the order in which the syllabus is taught at SHS, you can:

• Click here to view the general sequence of the SHS course here
• Click here for the SHS units mapped to the IB Biology curriculum roadmap
• Click here for the SHS units mapped to the Skills in the Study of Biology  in progress
• Click here for the SHS units mapped to the Nature of Science  in progress

The IB Biology curriculum is organized by themes (A-D) and levels of organization (1-4) in a "roadmap."​

THEME	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]   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
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 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
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 ​C2.2 Neural signaling	C3.1 Integration of body systems ​C3.2 Defense 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 Mutation 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 Stability and change ​D4.3 Climate change