Conceptual difficulties experienced by introductory college biology students studying gene expression are explored in this empirical study. We used an open-ended assessment instrument and a pre-test/post-test design to measure prior knowledge and conceptual change over the course of one semester. Our findings suggest that introductory biology students struggle with the basic terminology necessary to understand complex biological systems at the molecular and genetic level. While conceptual growth from the beginning to the end of the semester was less than expected, learning gains were significant for all concepts examined by our assessment strategy. Qualitative evaluation of pre- and post-tests further highlighted the difficulty students have articulating their knowledge using scientific language. In our discussion, we emphasize the importance of assessing conceptual understanding, developing instructional strategies to promote conceptual change, and the need for closer alignment of curriculum between and within institutions. Ultimately, educational and institutional resources to support faculty development in the area of teaching and learning are critical for the retention and preparation of a diverse student population in the biological sciences.
