This paper presents the results of a research whose objective was to identify and analyze the elements considered determinants, by biologists and undergraduating students in Biological Sciences, in the choice of his course, pointing to the formal and mainly informal roots for that option. The data were collected by means of 20 micro interviews, that were analyzed in terms of the relationship with the knowledge, proposed by Charlot (2000). It was detect a predominance of informal roots, for example, the identification with the issues related to biology, the influence of family, friends and daily life of the interviewee. In turn, the identification with the disciplines of Science/Biology and with their teachers were important determinants for those who had a formal root for the choice of this course.
formal and informal science education; professional choice; relation with knowledge.