Which of the following describes a component of the phosphorus cycle?

• A. Photosynthesis is the only process involved.
• B. Weathering of rocks releases phosphate, uptake by organisms, mineralization, sedimentation, runoff.
• C. Methane oxidation drives the cycle.
• D. Nitrogen fixation controls phosphorus transport.

Answer: (B)

Understanding how phosphorus moves through ecosystems requires recognizing that it mostly travels in solid and dissolved forms, not as a gas. The key sequence starts with weathering of phosphate-containing minerals in rocks, which releases phosphate into soils and waters. Plants and microorganisms take up this inorganic phosphate to build their tissues. When organisms die or waste products are mineralized, the phosphate is released back into the environment. Phosphate can then become buried in sediments (sedimentation) or be carried by runoff into water bodies, linking land and aquatic systems. Over long timescales, buried phosphate can re-enter the cycle through geological processes. This description—weathering releasing phosphate, uptake by organisms, mineralization, sedimentation, and runoff—best captures the major steps and flow of phosphorus in ecosystems. The other options point to processes from other nutrient cycles or misstate the role of these processes in transporting phosphorus.