1 heterotrophs is the animal we are talking about now, including people. Nitrogen source is organic matter: 20 kinds of α -amino acids. Ruminants are a little special, and they can use non-protein nitrogen (inorganic substances): urea, ammonia, (and possibly others). Autotrophic organisms are plants. They use inorganic substances to absorb in the form of ions, which is their nitrogen source. (Some plants can also eat meat, which is considered as utilization.

Microscopic examination: 1 heterotrophs: heterotrophs obtained organic substances by predation, digested and absorbed these small molecules and synthesized them into its own substances, such as polysaccharides, protein, nucleic acids and lipids. This is the assimilation of heterotrophs (an ordinary animal), so its nitrogen source comes from organic matter. Autotrophic organisms refer to organisms that live and reproduce only with inorganic compounds, so their nitrogen source is inorganic substances.