In this case study lesson, students investigate the popular claim that turkey causes post-Thanksgiving drowsiness by exploring how the amino acid tryptophan is converted into the hormone melatonin. Through guided analysis of metabolic and signal transduction pathways, students trace the molecular steps from digestion to hormonal signaling, interpret models and data, and evaluate claims using scientific evidence. All tasks are written in the language and style of the AP Biology Exam, helping stud