What is the role of decomposers in ecosystems?

• A. Decomposers eat only producers.
• B. Decomposers produce oxygen.
• C. Decomposers convert sunlight into energy.
• D. Decomposers break down dead organisms and release nutrients back into the system for reuse.

Answer: (D)

Decomposition and nutrient cycling are essential to ecosystems. Decomposers such as bacteria and fungi break down dead organisms and waste, using enzymes to convert complex materials into simpler nutrients that are released back into soil, water, or air. These nutrients then become available for producers to use again, supporting ongoing growth and energy flow through the ecosystem. Oxygen production comes from photosynthesis by plants and algae, not from decomposers, and decomposers do not turn sunlight into energy; they obtain energy by breaking down organic matter. That recycling of nutrients is why the description of decomposers breaking down dead matter and releasing nutrients for reuse fits best.