IB Environmental Systems and Societies Practice Exam 2026 – Comprehensive Study Guide

The pyramid of biomass specifically illustrates the biomass present at each trophic level in an ecosystem. Biomass refers to the total mass of living matter in a given area or volume, measured in grams per square meter (g/m²).

In a pyramid of biomass, the bars or sections represent the amount of living material available at each trophic level, typically showing how biomass decreases as one moves up from producers to top predators. This decrease occurs because energy transfer between trophic levels is inefficient, leading to less biomass at higher levels compared to lower ones where energy is more abundant and supports greater quantities of living organisms.

Understanding the concept of biomass is crucial for assessing ecosystem health and productivity, and it provides valuable insights into the relationships and energy dynamics between different organisms within an ecosystem. The other options refer to aspects such as organism numbers, energy flow, and biodiversity, which are not captured directly by the pyramid of biomass.