In a food pyramid, which statement is true?

• A. Energy increases as you move up the pyramid
• B. Energy decreases as you move up the pyramid
• C. Energy remains constant at all levels
• D. Energy is not related to trophic levels

Answer: (B)

Energy flow in ecosystems drives this pattern: energy decreases as you move up the trophic levels. Plants capture energy from the sun and store it as chemical energy, but only a portion becomes biomass that animals can eat. When organisms use energy for growth, movement, and maintaining bodily functions, much of it is lost as heat and through respiration, so less energy is available to the next level. Because only part of the energy at one level transfers to the next (often around 10%), there’s progressively less energy to support organisms higher up. That’s why the base holds the most energy and the top levels have the least.