Abstract
Understanding molecular processes and coordinating the various activities across levels of organization in biological systems is a complicated task, yet many curricular guidelines indicate that undergraduate students should master it. Employing mechanistic reasoning can facilitate describing and investigating biological phenomena. Biofilms are an important system in microbiology and biology education. However, few empirical studies have been conducted on student learning of biofilms or how students utilize mechanistic reasoning related to systems thinking to explain biofilm formation. Using mechanistic reasoning and the theory of knowledge integration as conceptual and analytical frameworks, we examined the features of 9 undergraduate biology students' mechanistic models of a specific transition point in biofilm development. From these data, we constructed a model of knowledge integration in the context of biofilms, which categorizes students' knowledge based on features of their descriptions (e.g., entities, correct connections, and the nature of connections). We found that 4 of 9 students produced a fragmented model, 4 of 9 students produced a transitional model, and 1 student produced a connected model. Overall, students often did not discuss cell-cell communication mechanics in their mechanistic models and rarely included the role of gene regulation. Most connections were considered nonnormative and lacked important entities, leading to an abundance of unspecified causal connections. We recommend increasing instructional support of mechanistic reasoning within systems (e.g., identifying entities across levels of organization and their relevant activities) and creating opportunities for students to grapple with their understanding of various biological concepts and to explore how processes interact and connect in a complex system.