What is a trophic level? Distinguish among producers (autotrophs), consumers (heterotrophs), decomposers, and detritus feeders (detritivores), and give an example of each in an ecosystem. Describe the processes of photosynthesis. Distinguish among primary consumers (herbivores), carnivores, secondary consumers, tertiary consumers, and omnivores, and give an example of each. Explain why there is little waste in nature and why humans are a major exception to this natural process.