What happens to the amount of energy at successive trophic levels?

It decreases.

The correct answer is c) It decreases.

The amount of energy available at successive trophic levels in an ecosystem decreases. This phenomenon is known as the ecological pyramid or the pyramid of energy. It is based on the 10% rule, which states that only approximately 10% of the energy available at one trophic level is transferred to the next trophic level.

When energy is transferred from one trophic level to another, a significant portion of it is lost as heat during metabolic processes, such as respiration, and is not available for consumption by the next trophic level. Additionally, energy is also used by organisms for growth, reproduction, and other life processes.

As a result, each trophic level has less energy available compared to the previous trophic level. For example, if the primary producers (plants) capture 100 units of energy through photosynthesis, only approximately 10 units of that energy are transferred to the herbivores (primary consumers) that feed on them. The carnivores (secondary consumers) that feed on the herbivores receive only around 1 unit of energy, and so on.

This energy loss and decrease in available energy limit the number of trophic levels that can be supported in a food chain or food web. It is why ecological pyramids typically have a larger biomass and number of organisms at lower trophic levels (producers) and fewer organisms at higher trophic levels (carnivores).

Understanding the decrease in energy at successive trophic levels is essential for comprehending energy flow, trophic interactions, and the dynamics of ecosystems. It helps explain why there are typically fewer top-level predators compared to primary producers and why energy availability is a crucial factor in shaping the structure and functioning of ecosystems.