Which cycle describes the movement of nitrogen and phosphorus through ecosystems?

Which cycle describes the movement of nitrogen and phosphorus through ecosystems?

• A. Nutrient cycle
• B. Carbon cycle
• C. Water cycle
• D. Hydrologic cycle

Answer: (A)

Nutrients cycle through ecosystems as essential elements move among air, soil, water, and living organisms and are transformed by biological and chemical processes. The movement of nitrogen and phosphorus fits this idea because these nutrients don’t stay tied up in one place forever—they are taken up by plants, moved through food webs, released back into the environment through decomposition, and can end up in soils or sediments for reuse. Nitrogen has a variety of transformations (like fixing, nitrification, assimilation, and denitrification) that shuttle it between atmospheric, aquatic, and terrestrial reservoirs, while phosphorus mainly leaches from rocks into soils and waters, gets taken up by organisms, and eventually returns to sediments. This broad, interconnected cycling of multiple nutrients is what the nutrient cycle describes. The carbon cycle and the water (hydrologic) cycle are related ideas but focus on different substances. The carbon cycle tracks carbon atoms through living systems and the atmosphere, whereas the water cycle follows the movement of water itself. Neither alone captures the joint movement and transformations of nitrogen and phosphorus that the nutrient cycle encompasses.

Nutrients cycle through ecosystems as essential elements move among air, soil, water, and living organisms and are transformed by biological and chemical processes. The movement of nitrogen and phosphorus fits this idea because these nutrients don’t stay tied up in one place forever—they are taken up by plants, moved through food webs, released back into the environment through decomposition, and can end up in soils or sediments for reuse. Nitrogen has a variety of transformations (like fixing, nitrification, assimilation, and denitrification) that shuttle it between atmospheric, aquatic, and terrestrial reservoirs, while phosphorus mainly leaches from rocks into soils and waters, gets taken up by organisms, and eventually returns to sediments. This broad, interconnected cycling of multiple nutrients is what the nutrient cycle describes.

The carbon cycle and the water (hydrologic) cycle are related ideas but focus on different substances. The carbon cycle tracks carbon atoms through living systems and the atmosphere, whereas the water cycle follows the movement of water itself. Neither alone captures the joint movement and transformations of nitrogen and phosphorus that the nutrient cycle encompasses.