This article describes the development of the Molecular Biology Capstone Assessment, a multiple-true/false concept assessment targeted to upper-division students. This assessment is intended to help pinpoint areas of conceptual difficulty among graduating majors in order to facilitate curricular change at the departmental level.
Measuring students’ conceptual understandings has become increasingly important to biology faculty members involved in evaluating and improving departmental programs. We developed the Molecular Biology Capstone Assessment (MBCA) to gauge comprehension of fundamental concepts in molecular and cell biology and the ability to apply these concepts in novel scenarios. Targeted at graduating students, the MBCA consists of 18 multiple-true/false (T/F) questions. Each question consists of a narrative stem followed by four T/F statements, which allows a more detailed assessment of student understanding than the traditional multiple-choice format. Questions were iteratively developed with extensive faculty and student feedback, including validation through faculty reviews and response validation through student interviews. The final assessment was taken online by 504 students in upper-division courses at seven institutions. Data from this administration indicate that the MBCA has acceptable levels of internal reliability (α = 0.80) and test–retest stability (r = 0.93). Students achieved a wide range of scores with a 67% overall average. Performance results suggest that students have an incomplete understanding of many molecular biology concepts and continue to hold incorrect conceptions previously documented among introductory-level students. By pinpointing areas of conceptual difficulty, the MBCA can provide faculty members with guidance for improving undergraduate biology programs.
Undergraduate students in genetics and developmental biology courses often struggle with the concept of epistasis because they are unaware that the logic of gene interactions differs between enzymatic pathways and signaling pathways. If students try to develop and memorize a single simple rule for predicting epistatic relationships without taking into account the nature of the pathway under consideration, they can become confused by cases where the rule does not apply. To remedy this problem, we developed a short pre-/post-test, an in-class activity for small groups, and a series of clicker questions about recessive epistasis in the context of a signaling pathway that intersects with an enzymatic pathway. We also developed a series of homework problems that provide deliberate practice in applying concepts in epistasis to different pathways and experimental situations. Students show significant improvement from pretest to posttest, and perform well on homework and exam questions following this activity. Here we describe these materials, as well as the formative and summative assessment results from one group of students to show how the activities impact student learning.
Note from the Editor
Points of View (POV) address issues faced by many people within the life science education community. CBE—Life Sciences Education (CBE-LSE) publishes the POV Feature to present two or more opinions published side-by-side on a common topic. We consider POVs to be “Op-Ed” pieces designed to stimulate thought and dialogue on significant educational issues. They are not meant to be exhaustive treatments of a subject.
In this issue, we ask the question, “What are key concepts in developmental biology?” We present three POVs. The first is by CBE-LSE Editor-in-Chief, William Wood, and it is in part based on his experience teaching developmental biology to undergraduates at the University of Colorado, Boulder, including his collaborative experiments in the classroom with Jennifer Knight, the first results of which have been published in CBE-LSE (Knight and Wood, 2005). The second, a partially tongue-in-cheek list of key concepts to convey to students about embryonic development, is by Scott Gilbert (Swarthmore College), author of the leading textbook worldwide for teaching developmental biology, Developmental Biology, 8th ed. (Sinauer Associates, Inc.). The third is by Jeff Hardin (University of Wisconsin–Madison), who has produced Web-based educational materials for teaching developmental biology that are used nationally and internationally for conveying dynamic events during early development (see the WWW feature in this issue by Stark for more details), and who deals with the vexing problem of trying to convey the essential four-dimensional nature of embryonic development to introductory students.
We have developed and validated a tool for assessing understanding of a selection of fundamental concepts and basic knowledge in undergraduate introductory molecular and cell biology, focusing on areas in which students often have misconceptions. This multiple-choice Introductory Molecular and Cell Biology Assessment (IMCA) instrument is designed for use as a pre- and posttest to measure student learning gains. To develop the assessment, we first worked with faculty to create a set of learning goals that targeted important concepts in the field and seemed likely to be emphasized by most instructors teaching these subjects. We interviewed students using open-ended questions to identify commonly held misconceptions, formulated multiple-choice questions that included these ideas as distracters, and reinterviewed students to establish validity of the instrument. The assessment was then evaluated by 25 biology experts and modified based on their suggestions. The complete revised assessment was administered to more than 1300 students at three institutions. Analysis of statistical parameters including item difficulty, item discrimination, and reliability provides evidence that the IMCA is a valid and reliable instrument with several potential uses in gauging student learning of key concepts in molecular and cell biology.
Whenever symmetry is broken in nature to yield only one of two equally probable outcomes, there is an intriguing problem to be solved.
MicroRNAs (miRNAs) have been found to regulate gene expression across eukaryotic species, but the function of most miRNA genes remains unknown. Here we describe how the analysis of the expression patterns of a well-conserved miRNA gene, mir-57, at cellular resolution for every minute during early development of Caenorhabditis elegans provided key insights in understanding its function. Remarkably, mir-57 expression shows strong positional bias but little tissue specificity, a pattern reminiscent of Hox gene function. Despite the minor defects produced by a loss of function mutation, overexpression of mir-57 causes dramatic posterior defects, which also mimic the phenotypes of mutant alleles of a posterior Hox gene, nob-1, an Abd homolog. More importantly, nob-1 expression is found in the same two posterior AB sublineages as those expressing mir-57 but with an earlier onset. Intriguingly, nob-1 functions as an activator for mir-57 expression; it is also a direct target of mir-57. In agreement with this, loss of mir-57 function partially rescues the nob-1 allele defects, indicating a negative feedback regulatory loop between the miRNA and Hox gene to provide positional cues. Given the conservation of the miRNA and Hox gene, the regulatory mechanism might be broadly used across species. The strategy used here to explore mir-57 function provides a path to dissect the regulatory relationship between genes.
miRNAs are small RNAs found in many multi-cellular species that inhibit gene expression. Many of them play important roles in cancer and cell fate determination, but the function of most miRNAs is uncertain. Using live cell imaging and automated expression analysis, we found a miRNA gene, mir-57, is expressed in a position rather than tissue dependent way. Hox genes also regulate cell fate patterning along anterior-posterior (a-p) axis across different tissues. By investigating interactions between genes of these classes expressed in mir-57 expressing cells, we demonstrated by both genetic analysis and gene expression assays that a negative feedback loop between a posterior Hox gene, nob-1, and mir-57 regulates posterior cell fate determination in C. elegans. On the one hand, the Hox gene is required for normal activation of mir-57 expression, and on the other, the Hox gene functions as a direct target of and is repressed by the miRNA. Given the conservation of the two genes, a negative feedback loop between Hox and miRNA genes might be broadly used across species to regulate cell fate along the a-p axis. Detailed expression analysis may provide a general way to dissect the regulatory role of miRNAs.
We have designed, developed, and validated a 25-question Genetics Concept Assessment (GCA) to test achievement of nine broad learning goals in majors and nonmajors undergraduate genetics courses. Written in everyday language with minimal jargon, the GCA is intended for use as a pre- and posttest to measure student learning gains. The assessment was reviewed by genetics experts, validated by student interviews, and taken by >600 students at three institutions. Normalized learning gains on the GCA were positively correlated with averaged exam scores, suggesting that the GCA measures understanding of topics relevant to instructors. Statistical analysis of our results shows that differences in the item difficulty and item discrimination index values between different questions on pre- and posttests can be used to distinguish between concepts that are well or poorly learned during a course.
We carried out an experiment to determine whether student learning gains in a large, traditionally taught, upper-division lecture course in developmental biology could be increased by partially changing to a more interactive classroom format. In two successive semesters, we presented the same course syllabus using different teaching styles: in fall 2003, the traditional lecture format; and in spring 2004, decreased lecturing and addition of student participation and cooperative problem solving during class time, including frequent in-class assessment of understanding. We used performance on pretests and posttests, and on homework problems to estimate and compare student learning gains between the two semesters. Our results indicated significantly higher learning gains and better conceptual understanding in the more interactive course. To assess reproducibility of these effects, we repeated the interactive course in spring 2005 with similar results. Our findings parallel results of similar teaching-style comparisons made in other disciplines. On the basis of this evidence, we propose a general model for teaching large biology courses that incorporates interactive engagement and cooperative work in place of some lecturing, while retaining course content by demanding greater student responsibility for learning outside of class.
undergraduate students; developmental biology; peer instruction; just-in-time teaching; concept maps
The 1998 Boyer Commission Report advocated improvement of undergraduate education at large research universities through large-scale participation of undergraduates in the universities' research mission. At a recent conference sponsored by the Reinvention Center, which is dedicated to furthering the goals of the Boyer Commission, participants discussed progress toward these goals and recommendations for future action. A breakout group representing the life sciences concluded that independent research experience for every undergraduate may not be feasible or desirable but that transformation of lecture courses to more inquiry-based and interactive formats can effectively further the Commission's goals.
Reinvention Center; independent research; assessment; course transformation
A recently released National Research Council (NRC) report, Learning and Understanding: Improving Advanced Study of Mathematics and Science in U.S. High Schools, evaluated and recommended changes in the Advanced Placement (AP), International Baccalaureate (IB), and other advanced secondary school science programs. As part of this study, discipline-specific panels were formed to evaluate advanced programs in biology, chemistry, physics, and mathematics. Among the conclusions of the Content Panel for Biology were that AP courses in particular suffer from inadequate quality control as well as excessive pressure to fulfill their advanced placement function, which encourages teachers to attempt coverage of all areas of biology and emphasize memorization of facts rather than in-depth understanding. In this essay, the Panel's principal findings are discussed, with an emphasis on its recommendation that colleges and universities should be strongly discouraged from using performance on either the AP examination or the IB examination as the sole basis for automatic placement out of required introductory courses for biology majors and distribution requirements for nonmajors.
Advanced Placement; College Board; International Baccalaureate; pedagogy
experiential learning; problem-based learning; case studies approach
C. elegans is proving useful for the study of cell determination in early embryos. Breeding experiments with embryonic lethal mutants show that abnormal embryogenesis often results from defective gene function in the maternal parent, suggesting that much of the information for normal embryonic development is laid down during oogenesis. Analysis of a gut-specific differentiation marker in cleavage-arrested embryos has provided evidence that the potential for this differentiation behaves as a cell-autonomous internally segregating developmental determinant, which is present from the 2-cell stage onward and is partitioned into the gut precursor cell during early cleavage divisions. Visible prelocalized cytoplasmic granules that segregate with a particular cell lineage have heen observed in the embryonic germline precursor cells by fluorescent antibody staining. Whether these granules play a role in germline determina... [remainder of abstract missing in original]