Vee diagrams have been a metacognitive tool to help in learning the nature and structure of knowledge by reflecting on the scientific process and making knowledge much more explicit to learners during the practical work. This study aimed to assess pre-service science teachers' understanding some aspects of NOS by analyzing their reflections on the Vee diagrams constructed during the general biology laboratory course. In this single case study, elementary pre-service science teachers who cited mainly "the cell theory" in their Vee diagrams while building around the cell concepts were asked to participate in focus group reflective interviews. These interviews compared the patterns of the nature of scientific knowledge to the ways their constructed the cell related concepts. The content analysis of transcripts revealed that pre-service teachers gained a superficial understanding of history of scientific ideas in the development of the cell biology, not a deeper epistemological understanding in conceptualizing a contemporary understanding of the aspects of NOS. The emergent categories of naive understandings and misconceptions held by the participants were demonstrated and discussed in the light of NOS related literature.