Which cycle involves the movement of phosphorus through rocks, organisms, and back to rocks?

• A. Carbon Cycle
• B. Nitrogen Cycle
• C. Phosphorus Cycle
• D. Water Cycle

Answer: (C)

The main idea is how phosphorus moves through rocks, living beings, and back into rocks. This cycle is mainly sedimentary, with no significant atmospheric component, so phosphorus travels through weathering of rocks into soils and waters, uptake by plants, and transfer through the food chain. When organisms die or excrete waste, phosphate returns to soil or water, and over time it can become part of sediments that form new rocks. Geological processes can then expose these rocks again, continuing the cycle. Human activities like mining phosphate rock and nutrient runoff can disrupt this balance, but the essential path remains rocks → organisms → rocks, without a major gas phase. In contrast, the carbon and nitrogen cycles rely heavily on atmospheric forms and exchanges, while the water cycle centers on movement of water rather than long-term nutrient storage in rocks.