IB Environmental Systems and Societies (ESS) Practice Exam 2025 – Your Comprehensive All-in-One Guide to Exam Success!

The correct term that describes the total gain in energy by consumers through absorption is Gross Secondary Productivity (GSP). GSP refers to the total amount of energy that is assimilated by consumers from the food they consume, before accounting for losses due to respiration or other metabolic processes. It encompasses all the energy taken in by consumers through their feeding processes, indicating how much energy they are gaining overall from their food sources.

This measure is crucial in understanding the energy flow within ecosystems, as it provides insight into how efficiently energy is utilized by consumers and how much energy moves up the food chain. GSP is foundational for studying food webs and energy transfer among different trophic levels in ecological research.

In contrast, Net Secondary Productivity (NSP) accounts for the energy that is available for growth and reproduction, after subtracting the energy lost through respiration from the total absorption. Meanwhile, Gross Primary Productivity (GPP) refers to the total energy captured by autotrophs (producers) through photosynthesis, while Net Primary Productivity (NPP) represents the energy available to consumers after subtracting the energy used by producers for their metabolic processes. These measures operate at different levels of the food chain and usage of energy, clarifying the roles of producers and consumers in