An inverted pyramid of biomass can be found in which ecosystem?

The correct answer is B, Marine. In the sea the producers are tiny phytoplankton. At any given moment their total mass is smaller than the mass of the zooplankton and fish that feed on them, so the pyramid of biomass stands upside down. This happens because phytoplankton grow and divide very fast and are eaten almost as quickly as they are produced, so a small standing crop can support a larger mass of consumers. The pyramid of energy, however, is always upright in every ecosystem, because energy is lost as heat at each step and only about 10 percent passes to the next level. Option A is wrong because in a grassland the grasses far outweigh the grazing animals, giving an upright pyramid. Option C is wrong because the tundra also has more plant mass than animal mass. Option D is wrong because in a forest the huge trees give a large biomass base, so the pyramid of biomass is upright, even though the pyramid of numbers there can be inverted. Exam tip: numbers can be inverted in a tree ecosystem, biomass in the sea, but energy never.