Purdue University Graduate School

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posted on 2022-04-28, 19:25 authored by Sharleen FlowersSharleen Flowers

In recent years, science has shifted from a focus on reductionist explanations of biological phenomena to a more integrated, systems approach. This shift has made its way into curricular recommendations for undergraduate education. To understand complex biological phenomena, it has been argued that students employ mechanistic reasoning, in which one describes a mechanism by identifying the activities that produce change, the entities which engage in activities, and the starting and ending conditions. Students’ use of mechanistic reasoning requires engaging in the complex task of simultaneously integrating and coordinating multiple elements across space and time. In addition, students must link and organize their scientific ideas and then structure their thoughts into a network of knowledge, as described by the theory of knowledge integration. Previous studies that have explored students’ understanding of scientific concepts using knowledge integration as a lens found that students’ nonmechanistic ideas prevented them from identifying gaps in the connections between their ideas and from forming normative knowledge. Thus, this dissertation investigates the features of undergraduate biology students’ systems thinking using knowledge integration and mechanistic reasoning as conceptual and analytical frameworks. Using a semi-structured interview, we asked students to describe functional definitions of and relationships between three fundamental modules in biology (i.e., gene regulation, cell-cell communication, and the relationship between genotype and phenotype). In the first study, we found that the majority of students did not have normative functional definitions for how and why gene regulation occurs or how phenotype is regulated. When describing the relationships in an open context, most students expressed unidirectional, linear knowledge networks which lacked Mechanistic connections. In our second study, we examined how students described a transition point in biofilm development after being cued to think about the three modules. Though students struggled to transfer over relevant ideas to the biofilm context (such as gene regulation and cell-cell communication processes), we found that explanations were more specified in the nature of connections and content including more Mechanistic descriptions. In the third study, we explored features of biology students’ and instructors’ knowledge networks in an open context and situated to a context of the participants’ choice. Within an open context, most students described multidirectional, non-linear knowledge networks similar to instructors. In the specific context, the majority of students described non-linear knowledge networks, but some students modified their structures to be linear. Although the structures became less complex in the specific context, the nature of connections and content became more specified. Across all studies, we found that context greatly affected students’ systems thinking as revealed by the changing features of the knowledge networks. Specifically, context helped students identify what relationships they deeply understood and could transfer and allowed for the creation of a detailed explanation relevant to the specific biological phenomenon. For students to develop a broad systems perspective of biology, we recommend instructors engage students in the process of knowledge integration. Embed opportunities for students to think about biology concepts in various contexts, particularly where students grapple with nuanced and complex transfer of ideas. These practices will encourage students to form causal, mechanistic linkages between concepts and build an integrated, expert-like understanding of biology.


Degree Type

  • Doctor of Philosophy


  • Biological Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Stephanie M. Gardner

Additional Committee Member 2

Ala Samarapungavan

Additional Committee Member 3

Nancy J. Pelaez

Additional Committee Member 4

Thomas M. Walter