Which term describes the total mass of living matter in a given unit area?

• A. Trophic Level
• B. Biomass
• C. Phase Shift
• D. Primary Succession

Answer: (B)

Biomass is the total mass of living matter in a given area. It includes all organisms from microbes to plants and animals and is typically measured as dry weight per unit area (for example, g/m² or kg/m²). This makes biomass a standing-stock measure of how much living material is present at a point in time, useful for comparing ecosystem productivity and the amount of living matter available to support consumers.

This differs from a trophic level, which is the position an organism occupies in a food chain, not how much matter it has. It also isn’t about shifts in ecosystem structure (phase shifts) or the process of a landscape becoming populated by organisms (primary succession). Those terms describe dynamics and structure, whereas biomass quantifies the actual mass of living material in the area.