Which statement about chemical nutrients in an ecosystem is true?

Which statement about chemical nutrients in an ecosystem is true?

• A. They come from plants.
• B. They do not move between organisms.
• C. They cycle within the ecosystem and are constantly reused.
• D. They are destroyed after one use.

Answer: (C)

The main idea here is nutrient cycling: chemical nutrients are recycled and reused within an ecosystem, not used up and discarded. In ecosystems, nutrients originate from rocks, soil, and the atmosphere. Plants take up mineral nutrients and incorporate them into organic matter. Animals obtain nutrients by eating plants or other organisms. When organisms die or produce waste, decomposers break down the material, releasing inorganic nutrients back into the soil, water, or atmosphere. Those nutrients are then available again for uptake by plants, continuing the loop. This continual recycling keeps nutrients within the system rather than being permanently destroyed. That’s why the statement about cycling and constant reuse is the best answer. The idea that nutrients come only from plants isn’t accurate, since sources include rocks and air and they move through food webs via consumption and decomposition. The notion that nutrients are destroyed after one use contradicts the conservation of matter and the observed cycles that continually replenish nutrient availability.

The main idea here is nutrient cycling: chemical nutrients are recycled and reused within an ecosystem, not used up and discarded. In ecosystems, nutrients originate from rocks, soil, and the atmosphere. Plants take up mineral nutrients and incorporate them into organic matter. Animals obtain nutrients by eating plants or other organisms. When organisms die or produce waste, decomposers break down the material, releasing inorganic nutrients back into the soil, water, or atmosphere. Those nutrients are then available again for uptake by plants, continuing the loop. This continual recycling keeps nutrients within the system rather than being permanently destroyed.

That’s why the statement about cycling and constant reuse is the best answer. The idea that nutrients come only from plants isn’t accurate, since sources include rocks and air and they move through food webs via consumption and decomposition. The notion that nutrients are destroyed after one use contradicts the conservation of matter and the observed cycles that continually replenish nutrient availability.