What is a nutrient cycle?

• A. A system for recycling plastic in ecosystems.
• B. The movement of nutrients through an ecosystem, such as the carbon or water cycle, involving producers, consumers, and decomposers.
• C. A cycle of nutrient storage in soil only.
• D. A process where light energy is converted into nutrients.

Answer: (B)

A nutrient cycle shows how nutrients move and get reused in an ecosystem. Producers transform elements into usable compounds, and consumers move those nutrients as they eat. Decomposers break down waste and dead organisms, returning nutrients to the soil, water, or air so the cycle can start again. This cycling happens across air, water, soil, and living things, with elements like carbon and nitrogen moving through the system as part of the cycles we study.

The option that describes the movement of nutrients through an ecosystem, involving producers, consumers, and decomposers, and noting cycles such as carbon or water, is the best fit because it captures the nonstop flow and reuse of nutrients that characterizes nutrient cycles.

Recycling plastic in ecosystems isn’t a natural nutrient cycle because plastics aren’t nutrients for organisms and aren’t part of the natural recycling loops. A cycle stored only in soil doesn’t capture how nutrients move through air, water, and living beings. And turning light energy into nutrients describes photosynthesis, not a nutrient cycle.