Assess students' understanding of nitrogen and phosphorus biogeochemical cycling in freshwater ecosystems (lakes, reservoirs, rivers), covering major sources and sinks, microbial transformations (mineralization, nitrification, denitrification), sediment–water interactions, controls on nutrient availability, indicators and ecological consequences of excess loading (algal blooms, hypoxia), and common prevention and remediation strategies; includes conceptual questions and interpretation of simple datasets or scenarios.