Ecosystem

• An ecosystem can be said to begin with producers, which are generally green plants that capture the sun's energy and use it to convert inorganic compounds into organic compounds. An example is the process of converting minerals, such as nitrogen, in soil into green leaves, apples or pumpkins. This is referred to as photosynthesis.
  
  

Primary Consumers

• Primary consumers eat parts of the producers. An example is a monkey eating a fruit or a cow eating grass. Through this, food energy and organic compounds are transferred from plants to animals.
  
  

Primary, Secondary and Tertiary Consumers

• Primary consumers are then eaten by secondary (a lion or bear) or tertiary consumers (a human who eats the bear). Obviously there are times when a tertiary consumer could consume a producer, such as when a human eats a carrot, or a primary consumer, such as when a human eats a cow).
  
  

The Food Chain is Completed

• The food chain eventually continues until the secondary and/or tertiary consumer dies, with the body being broken down and used as nutrition by decomposers, which are generally bacteria and fungi. As the decomposers feed on dead animals, they reduce complex organic compounds into simple nutrients. These nutrients are returned to the soil and are used again by the plants, thereby completing the food chain.
  
  

The Primary Consumer Affects the Entire Ecosystem

• Eliminating the primary consumer will eventually affect the entire ecosystem. If humans kill all deer in a forest, grasses will grow untamed and begin to affect trees and other plants. Secondary and tertiary consumers will be without a food source and either die out or be forced to travel to a new ecosystem.