A small set of relationships has been identified which appears to be sufficient for describing all molecular and cellular reactions and structures discussed in an introductory biology course. A precise definition has been developed for each relationship. These 20 relationships are of four types: (1) analytical; (2) spatial; (3) temporal; and (4) process. Three different computer-based semantic network representations of molecular biology knowledge were developed. Two list-structure nets were useful in identifying problems in net design. The most successful of the three prototypes involved spatial representations (concept maps) for each concept, with the maps being linked together to form a network. Various styles of knowledge representation were tested with students enrolled in introductory biology. The students were most enthusiastic about exercises in which partially completed concept maps were given to them and they had to fill in the missing pieces (concepts or relationships). The systematic analysis of relationships between concepts reveals relationships not explicitly perceived before, even by experts. It is believed that these representational techniques will be useful in facilitating student learning. (Author/JN)