Final answer:
The biomass of autotrophs is generally greater than that of herbivores due to the energy loss at each trophic level, where only about 10% of the energy is passed from one level to the next in the food chain.
Step-by-step explanation:
Autotrophs, such as plants, algae, and some photosynthetic bacteria, form the base of the ecosystem's food web by transforming solar energy into chemical energy through photosynthesis and storing it in organic molecules like glucose. The biomass of autotrophs is typically greater than that of herbivores because only about 10% of the energy from autotrophs is transferred to herbivores, which are primary consumers. This is illustrated in the concept of an energy pyramid, where the large base represents the greater biomass of autotrophs, and the levels above represent the progressively smaller biomass of herbivores and carnivores.
Herbivores, which are heterotrophs, obtain energy by consuming autotrophs, but the majority of energy is lost through respiration, heat, and other life processes. Therefore, the herbivores' biomass is only a fraction of the autotrophs' biomass they feed on. This energy loss between trophic levels contributes to the decrease in biomass as one moves up the food chain.