THEME C:  Interaction and Interdependence

The biology course is organized by theme.  Both standard level (SL) students and higher level (HL) students study the four themes at four levels of biological organization (molecules, cells, organisms and ecosystems).  HL students study some of these topics to greater depth. 

Theme C is Interaction and Interdependence

C1:  Interaction and Interdependence of Molecules​

C1.1 Enzymes and Metabolism

C1.2 Cell Respiration

C1.3 Photosynthesis

C2:  Interaction and Interdependence of Cells

C2.1 Chemical Signaling (HL only)

C2.2 Neural Signaling

C3:  Interaction and Interdependence of Organisms

C3.1  Integration of Body Systems

C3.2 Defense Against Disease

C4:  Interaction and Interdependence of Ecosystems

C4.1 Populations and Communities

​C4.2 Transfers of Energy and Matter