Which diagram compares energy used by producers, primary consumers, and other trophic levels, showing about 10 percent transfer between levels?

• A. Energy pyramid
• B. Food web
• C. Hydrologic cycle
• D. Biogeochemical cycle

Answer: (A)

The main idea is how energy is lost and passed along through trophic levels, which is best shown by an energy pyramid. Producers capture energy from the sun and store some as chemical energy, but much of that energy is used for metabolism or lost as heat. When energy moves to primary consumers and then to higher levels, only about 10% of the energy is typically transferred to the next level, so the amount of usable energy decreases with each step. That’s why an energy pyramid is shaped with a broad base and progressively smaller upper levels, reflecting the 10% transfer rule.

The other diagrams don’t depict energy quantities across trophic levels. A food web shows who eats whom, not the actual energy amounts at each level. The hydrologic cycle maps water movement, and the biogeochemical cycle tracks nutrient elements, not the pattern of energy transfer between producers and consumers.