How does energy flow in an ecosystem?

Energy flow in an ecosystem is a one-way process, primarily due to the laws of thermodynamics. When energy enters an ecosystem, it typically comes from the sun and is captured by producers, such as plants, through photosynthesis. These producers convert solar energy into chemical energy in the form of glucose.

Once this energy is captured by plants, it flows through the ecosystem as various organisms consume one another—herbivores eat the plants, and carnivores eat the herbivores. At each trophic level, energy is used for metabolic processes, and a significant portion is lost as heat. Because of this loss of energy at each level, it doesn't cycle back to the original source; rather, it flows in a linear fashion, moving from one trophic level to the next and ultimately being dissipated into the environment.

In contrast, options that suggest energy flows in cycles or randomly do not align with established ecological principles. Energy does not cycle back through the system in the way nutrients might, nor does it flow in random patterns. The directional flow—entering, being transformed, and ultimately dissipating—is a defining characteristic of energy movement in ecosystems.