Undergraduate research is a high-impact educational practice for which effective mentoring has been identified as a key factor in determining its success. Some researchers have argued that effective mentors help increase students' independence and ownership of the research project. This case study used conversation analysis to examine recorded interactions between an early-career postdoctoral mentor and a first-year undergraduate research student within the context of "mentoring by questioning" in a biochemistry research group. The study was based on three guiding research questions: What norms of discourse frame conversations about independence and ownership of research? How are the norms of discourse established? What impact do these conversations have on the undergraduate research experience? Analysis of the data collected in this study suggested three ways in which the mentor used the discursive tool of question-asking to guide conversations with the undergraduate research student: encouraging scientific observations, shifting responsibility, and encouraging critical thinking.