The biology course is organized by topics.  Both standard level (SL) students and higher level (HL) students study the six core topics.  HL students study an additional five topics, with some of these taking the first six topics to greater depth.  In addition to this, both SL and HL students study one out of a choice of four optional topics. 

Topic 7:  Nucleic Acids

Topic 8:  Metabolism, Cell Respiration and Photosynthesis

Topic 9:  Plant Biology

Topic 10:   Genetics and Evolution

Topic  11:  Animal Physiology