Testing for biological molecules — practice question

Complete the passage with the term that best fits. In any ecosystem, there is a ................................ of organisms that influence one another and also interact with the surroundings. Every species has a specific ................................ in that ecosystem. Feeding links in food webs show the interactions species have with one another. In old-field ecosystems in North America, producers such as blue grass supply energy to grazing animals. These animals make up the ................................ ................................ ................................ in the food chain.

Only a very small proportion of the energy taken in by grazing animals reaches carnivores. State two reasons why this occurs.