Decomposers return what to the ecosystem?

• A. Energy
• B. Nutrients
• C. Water
• D. Heat

Answer: (B)

Decomposition recycles nutrients in an ecosystem. When organisms die or produce waste, decomposers such as bacteria, fungi, and some invertebrates break down the organic matter. As they do, they convert complex molecules into simpler mineral nutrients—like nitrogen compounds, phosphorus, and carbon dioxide—that return to soil, water, or air. Plants then take up these nutrients to grow, and the cycle continues. Energy doesn’t get returned in a usable form; it moves through the system and is eventually released as heat. Water cycles through evaporation and precipitation, not directly through decomposition. So decomposers primarily restore nutrients for reuse by living things.