Question

In a food pyramid, There is typically less biomass at the top (i.e., there are very few individual tertiary consumers, where as whereas there are numerous individual producers). In three to five sentences, explain this phenomenon, citing evidence relating to energy flow and how plants support ecosystems. (4 points)

Answer 1

Energy flows upward through trophic levels but much of it is lost at each step as heat and through metabolic processes, so only about 10% (range ~1–20%) of the energy in one level is typically transferred to the next. Because primary producers (plants) capture and fix solar energy by photosynthesis, they generate the bulk of the ecosystem’s biomass (net primary productivity) that fuel all higher trophic levels. With so little energy left after successive transfers, there is not enough energy to support large numbers or large biomass of top predators, so tertiary consumers are scarce. Thus the efficiency of energy transfer and the central role of plants in creating usable biomass explain why biomass decreases toward the top of the food pyramid.