Using a design-based research approach, we developed a data-rich problem (DRP) set to improve student understanding of cellular respiration at the ecosystem level. The problem tasks engage students in data analysis to develop biological explanations. Several of the tasks and their implementation are described. Quantitative results suggest that students from the experimental class who participated in the DRP showed significant gains on cellular respiration posttest items, and students from the control class who participated in a non-DRP task showed no significant gains. Qualitative results from interviews and written responses showed that students from the experimental class progressed to deeper "levels of achievement" in cellular respiration. The data-rich tasks promote student understanding of cellular respiration, matter transformation, decomposition, and energy transformation--all goals recommended by the Next Generation Science Standards.