How does the cycling of matter through an ecosystem differ from the flow of energy?

• A. Energy is recycled within ecosystems, while matter flows in one direction and is lost.
• B. Both matter and energy are recycled continuously within ecosystems.
• C. Neither matter nor energy is recycled; both are lost from the ecosystem.
• D. Matter is recycled within ecosystems, while energy flows in one direction and is eventually lost as heat.

Answer: (D)

Verified step by step guidance

1. Understand the key concepts: Matter and energy behave differently in ecosystems. Matter refers to physical substances like carbon, nitrogen, and water, while energy refers to the ability to do work, often originating from the sun in ecosystems.
2. Recognize that matter is recycled: Matter cycles through ecosystems via biogeochemical cycles such as the carbon cycle, nitrogen cycle, and water cycle. These cycles allow matter to be reused by organisms over time.
3. Understand the flow of energy: Energy enters ecosystems primarily through sunlight, which is captured by producers (like plants) during photosynthesis. This energy is then transferred through the food chain but is not recycled.
4. Note the loss of energy: As energy moves through trophic levels (producers, consumers, decomposers), a significant portion is lost as heat due to metabolic processes, following the second law of thermodynamics. This means energy flows in one direction and is not reused.
5. Conclude the distinction: Matter is recycled within ecosystems through cycles, while energy flows in one direction and is eventually lost as heat, making the two processes fundamentally different.