The results of a study on conceptions of the nature of science (NOS) among Biology undergraduate students are presented here. Four factors potentially associated with the conceptions of this public were statistically tested: educational stage, course type (for pre-service biology teachers or biologists-in-training), contact with meta-scientific themes, and participation in science initiation. The participants were 691 students from 14 Brazilian universities, who answered a contextualized questionnaire about research in Ecology. There was no variation in conceptions between the different educational stages neither from contact with meta-scientific themes, nor participation in scientific initiation. Nonetheless, undergraduates attending only teacher-training courses presented less-informed NOS conceptions when compared with two other groups, one formed only by biologists-in-training and the other by a combination of biologists-in-training and teaching-training students. Among the 11 aspects of NOS investigated, the students presented less-informed conceptions about those addressing instrumentation and experimental practices. The discussion was directed to certain implications associated with the scenario presented.