Use of a short, in‐class, open‐ended free response activity to assess student understanding of the cell membrane in an undergraduate physiology course

Abstract

With an ever‐increasing body of information about human and animal physiology, it can be difficult for an instructor to decide what topics to focus on and what students exiting a single, stand‐alone physiology course should have learned. One valuable tool to assist in making these decisions is the set of 15 core concepts in physiology published by Michael and McFarland (Adv Physiol Educ 2011). Students in the upper division, stand‐alone physiology course at Missouri Western State University are required to have completed a freshman‐level introductory cell biology course and a sophomore‐level genetics course, but no other prerequisites are required. The prerequisite courses include discussion of the eukaryotic cell membrane and basic properties and functions of the membrane. However, many students remember the basic information about membrane structure but have difficulty relating that structure to membrane function and related topics in our physiology course, including vesicular transport, primary and secondary active transport, osmosis, and current flow across the membrane. To gain a better understanding of what students recall about the cell membrane before beginning in‐class discussion about membrane structure and function, students were given an open‐ended prompt, “What do you know about the animal cell membrane? Include structural characteristics and functions.” The students were allowed to work in small groups or alone if they preferred, and could generate their response as drawings, written statements, or both. They were given 10 minutes to construct a response. These student responses were analyzed using the conceptual framework for the “cell membrane” core concept recently published by Michael and Modell (Adv Physiol Educ 2019). 100% (19 out of 19) submissions included a drawing or description of the cell membrane as a phospholipid bilayer, and 84% of submissions included integral and peripheral membrane proteins. However, other components of the “cell membrane” conceptual framework were included much less frequently or not at all. While 58% of the responses listed diffusion or osmosis, only 32% listed active transport, and less than 10% mentioned vesicular transport, cell‐cell or cell‐matrix junctions, maintenance of solute concentration inside versus outside the cell, or cell‐to‐cell communication. No responses explicitly included simple diffusion of lipid‐soluble molecules, membrane receptors, ion channels, or physical separation/compartmentalization of the cell. Several responses had errors, such as incorrect labeled of the fatty acid tails of phospholipids as hydrophilic. This quick activity provides valuable information about what students recall from prior coursework and what concepts need to be revisited before moving into more detailed discussion of cell membrane function.