A biology textbook contains sentences such as “role of cytoskeleton is support and motility of a cell” and “NADH is an electron carrier that transfers electrons”. The first sentence explicitly uses the word role while in the second sentence the role of electron carrier is implicit. Role concepts have been defined in the context of upper ontologies for some time, but the word role has also been used in linguistics and description logics to denote related but different notions. In this paper, we consider the roles in a biology textbook, adapt a definition of roles based on upper ontologies, and relate it to the corresponding notions in linguistics and description logics. We consider our solutions to several conceptual modeling problems for roles as we have used them in representing the knowledge contained in a biology textbook. The primary contribution of this work is in applying the representation of roles to a complex and challenging domain, in giving definitions that can be applied by biologists, and in collecting several concrete examples that require such representation.