What does an energy pyramid illustrate?

What does an energy pyramid illustrate?

• A. All trophic levels have the same amount of energy.
• B. Energy decreases upward, with producers at the bottom and top predators at the top.
• C. Energy increases at higher trophic levels.
• D. Only the top predator uses energy from producers.

Answer: (B)

Energy moves through an ecosystem in a one-way flow from the sun to producers and then through successive feeding levels. At each step, only a portion of the energy is stored in the next level; much of the rest is lost as heat from metabolic processes, daily activity, and undigested material. Because of this continual loss, energy available declines as you move upward from producers at the base to herbivores, then to carnivores, and finally to top predators. That’s why the base has the most energy and the top has the least. The statement that best fits this pattern is that energy decreases upward, with producers at the bottom and top predators at the top. The other ideas—equal energy at all levels, energy increasing higher up, or only the top predator using energy from producers—don’t reflect how energy actually flows through ecosystems.

Energy moves through an ecosystem in a one-way flow from the sun to producers and then through successive feeding levels. At each step, only a portion of the energy is stored in the next level; much of the rest is lost as heat from metabolic processes, daily activity, and undigested material. Because of this continual loss, energy available declines as you move upward from producers at the base to herbivores, then to carnivores, and finally to top predators. That’s why the base has the most energy and the top has the least. The statement that best fits this pattern is that energy decreases upward, with producers at the bottom and top predators at the top. The other ideas—equal energy at all levels, energy increasing higher up, or only the top predator using energy from producers—don’t reflect how energy actually flows through ecosystems.