Final answer:
Primary consumers are the organisms in the trophic level that receive the largest percentage of energy captured by producers. They directly eat producers and receive energy with the least amount of loss, as only 10 percent of energy gets passed on to the next trophic level.
Step-by-step explanation:
The organisms that are in the trophic level receiving the larger percentage of energy captured by producers are the primary consumers. These consumers directly consume the producers, such as plants, algae, and photosynthetic bacteria, and thus receive energy that has undergone the least amount of transfer. Since only about 10 percent of the energy at one trophic level is passed on to the next higher trophic level, primary consumers benefit the most from producers' energy conversion.
It's important to differentiate between gross primary productivity, which is the total energy captured by producers, and net primary productivity, which is the energy that remains after producers have used some for their own growth and reproduction. The remaining energy is what's available to the primary consumers. Because energy is lost at each transfer, higher trophic levels, such as secondary and tertiary consumers, have even less energy available to them, resulting in fewer organisms and less biomass as one moves up the ecological pyramid.