Nutrition is the process of assimilating food materials by living organisms in order to grow, maintain, and reproduce. There are two main types of nutrition: chemotrophic and holozoic. Chemotrophic nutrition is a type of nutrition that converts one type of chemical into another. This is usually done by bacteria, as shown in Figure 2.Holozoic nutrition is a type of heterotrophic nutrition that involves the ingestion and internal digestion of gaseous, liquid, or solid food particles.
This type of nutrition is usually performed by animals. As seen in Figure 6, energy stored in organic matter circulates between living organisms as a result of their different types of nutrition.