- A The circular, rotating water currents that form naturally within flowing streams, a hydrological pattern unrelated to nutrient cycling between organisms and water
- B Downstream transport and cycling of nutrients -- nutrients spiral through biotic and abiotic forms while being transported downstream
- C The cycling of phosphorus specifically, occurring independently of any other nutrient, excluding nitrogen, carbon, and other nutrients that also spiral downstream
- D The natural meandering and lateral movement of a river channel over time, a geomorphological process distinct from nutrient transport and uptake
Correct answer: B. Downstream transport and cycling of nutrients -- nutrients spiral through biotic and abiotic forms while being transported downstream
Explanation: Nutrient spiraling: in streams, nutrients are taken up by organisms, processed, released, transported downstream, and taken up again. The spiraling length is the average distance traveled per uptake cycle.
Concept context
Ecosystems, food chains, energy flow, nutrient cycles, biodiversity, and conservation.