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Thesis Abstract

In this study, the persistence of students’ conceptual understanding of photosynthesis during biology instruction was examined to address persistent misconceptions that impede advanced understanding. The research aimed to (1) quantify baseline misconception prevalence among undergraduate biology majors, (2) evaluate the effectiveness of a theory-driven instructional intervention grounded in constructivist learning theory and cognitive load theory, and (3) develop a validated framework for measuring conceptual change in plant biology topics. Specific objectives include mapping pre-existing mental models of photosynthesis, implementing a repeated-measures experimental design with a control group, and triangulating quantitative outcomes with qualitative insights to illuminate the mechanisms of conceptual change. The methodology employed a mixed-methods design across two successive semesters at a mid-sized research university. The population comprised 320 second-year biology undergraduates enrolled in an introductory plant biology course, from which 180 participants were randomly assigned to either an intervention (n=90) or control (n=90) condition. Data collection involved (a) a validated Photosynthesis Misconception Diagnostic Survey (PMDS) administered at three time points (pre-test, post-test, and follow-up), (b) concept mapping tasks analyzed through a rubric-based structural similarity metric, and (c) semi-structured interviews with a purposive sample of 24 students to explore cognitive processes underpinning shifts in understanding. The intervention consisted of a six-week module incorporating inquiry-based experiments, worked-example problem sets, and metacognitive prompts designed to elicit cognitive conflict and conceptual restructuring, aligned with constructivist principles and germane load reduction strategies. Instructional delivery emphasized explicit linkages between light-dependent reactions and the Calvin cycle, energy transfer, and chloroplast structure, reinforced by visual simulations and collaborative discourse. Data analysis combined quantitative and qualitative approaches. Descriptive statistics characterized baseline misconception prevalence. Inferential analyses used mixed-effects repeated-measures ANOVA to assess changes over time between groups, with post-hoc comparisons corrected for multiple testing. Regression analyses identified predictors of conceptual change, including prior knowledge, engagement metrics, and attendance. The qualitative component employed thematic analysis of interview transcripts, coding for themes related to cognitive conflict, epistemic scaffolding, and metacognitive regulation. Triangulation of quantitative and qualitative findings sought to corroborate the proposed mechanisms of change and to refine the interpretation of diagnostic items. Expected findings indicate that the intervention will yield a statistically significant reduction in PMDS scores in the experimental group relative to controls (p < .05), with the most pronounced gains observable in students’ ability to accurately relate light reactions to carbon fixation and energy budgeting. Concept maps are anticipated to show increased structural coherence and alignment with canonical models of photosynthesis. Interviews are expected to reveal enhanced awareness of preconceptions and the deployment of metacognitive strategies, such as self-questioning and cognitive restructuring, as mediators of improvement. The study also anticipates identifying subgroups—e.g., students with lower initial content knowledge or weaker spatial reasoning—who benefit most from targeted cognitive scaffolds. The contribution to knowledge lies in (a) providing a replicable, theory-grounded instructional framework for correcting persistent misconceptions in core plant biology concepts, (b) offering a validated measurement approach that combines diagnostic surveys, concept mapping, and qualitative interviews to track conceptual change, and (c) elucidating the synergistic effects of constructivist pedagogy and cognitive load considerations on learning outcomes in biology education. The findings will inform curriculum design, instructional materials, and teacher professional development by detailing actionable strategies to scaffold conceptual change and sustain gains beyond immediate post-instruction assessment. The study concludes that deliberate, theory-informed interventions anchored in constructivism and cognitive load theory can meaningfully transform students’ mental models of photosynthesis, with implications for broader biology education practice and further research into scalable, discipline-specific interventions. Recommendations emphasize longitudinal implementation across multiple course levels, integration with assessment reform to monitor conceptual progression, and exploration of technology-enhanced tools to sustain conceptual coherence in complex bioscience topics.