The Design and Transformation of Biofundamentals: A Nonsurvey Introductory Evolutionary and Molecular Biology Course

How Do Instructors Explain The Mechanism by which ATP Drives Unfavorable Processes?

Concerns regarding students' difficulties with the concept of energy date back to the 1970s. They become particularly apparent for systems involving adenosine triphosphate (ATP), which plays a central role in maintaining the nonequilibrium state of biological systems and in driving energetically unfavorable processes. One of the most well-documented misconceptions related to ATP is the idea that breaking bonds releases energy, when the opposite is true. This misconception is often attributed to language used in biology referring to the "high-energy bonds" in ATP. We interviewed chemistry, biology, and biochemistry instructors to learn how they think about and teach the mechanism(s) by which ATP is used as an energy source in biological systems. Across 15 interviews, we found that instructors relied primarily on two mechanisms to explain the role of ATP: 1) energy release, focused on ATP hydrolysis and bond energies; and/or 2) energy transfer, focused on phosphorylation and common intermediates. Many instructors shared negative and uncomfortable experiences related to teaching ATP and energy release. Based on these findings, we suggest instructional strategies that: 1) aim to ease the concerns expressed by introductory biology instructors, and 2) emphasize the role of ATP so as to support students' understanding of molecular mechanisms.

Rethinking (again) Hardy-Weinberg and genetic drift in undergraduate biology

Designing effective curricula is challenging. Content decisions can impact both learning outcomes and student engagement. As an example consider the place of Hardy-Weinberg equilibria (HWE) and genetic drift calculations in introductory biology courses, as discussed by Masel (2012). Given that population genetics, "a fairly arcane speciality", can be difficult to grasp, there is little justification for introducing introductory students to HWE calculations. It is more useful to introduce them to the behavior of alleles in terms of basic features of biological systems, and that in the absence of selection recessive alleles are no "weaker" or preferentially lost from a population than are dominant alleles. On the other hand, stochastic behaviors, such as genetic drift, are ubiquitous in biological systems and often play functionally significant roles; they can be introduced to introductory students in mechanistic and probabilistic terms. Specifically, genetic drift emerges from the stochastic processes involved in meiotic chromosome segregation and recombination. A focus on stochastic processes may help counteract naive bio-deterministic thinking and can reinforce, for students, the value of thinking quantitatively about biological processes.

Energy Connections and Misconnections across Chemistry and Biology

Despite the number of university students who take courses in multiple science disciplines, little is known about how they connect concepts between disciplines. Energy is a concept that underlies all scientific phenomena and, as such, provides an appropriate context in which to investigate student connections and misconnections across disciplines. In this study, university students concurrently enrolled in introductory chemistry and biology were interviewed to explore their perceptions of the integration of energy both within and across the disciplines, and how they attempted to accommodate and reconcile different disciplinary approaches to energy, to inform future, interdisciplinary course reform. Findings suggest that, while students believed energy to be important to the scientific world and to the disciplines of biology and chemistry, the extent to which it was seen as central to success in their courses varied. Differences were also apparent in students' descriptions of the molecular-level mechanisms by which energy transfer occurs. These findings reveal a disconnect between how energy is understood and used in introductory science course work and uncovers opportunities to make stronger connections across the disciplines. We recommend that instructors engage in interdisciplinary conversations and consider the perspectives and goals of other disciplines when teaching introductory science courses.

Diagnostic of students' misconceptions using the Biological Concepts Instrument (BCI): A method for conducting an educational needs assessment

Concept inventories, constructed based on an analysis of students’ thinking and their explanations of scientific situations, serve as diagnostics for identifying misconceptions and logical inconsistencies and provide data that can help direct curricular reforms. In the current project, we distributed the Biological Concepts Instrument (BCI) to 17-18-year-old students attending the highest track of the Swiss school system (Gymnasium). Students’ performances on many questions related to evolution, genetics, molecular properties and functions were diverse. Important common misunderstandings were identified in the areas of evolutionary processes, molecular properties and an appreciation of stochastic processes in biological systems. Our observations provide further evidence that the BCI is efficient in identifying specific areas where targeted instruction is required. Based on these observations we have initiated changes at several levels to reconsider how biological systems are presented to university biology studies with the goal of improving student’s foundational understanding.