How does animal bioenergetics help explain the net production pyramid?

As you just learned, in real ecosystems, trophic efficiencies usually vary from about 5% to about 20%. As a result, net production diagrams for ecosystems have a pyramid shape. Two key factors explain why trophic efficiencies are relatively low, and thus why net production diagrams are shaped like pyramids.

First, not all the organisms at one trophic level are eaten by organisms at the next trophic level. For example, not every plant is eaten by herbivores, and not every herbivore is eaten by carnivores.

Second, because of the bioenergetics of animals, not all the food an animal eats is converted to new biomass. As you learned in Part A, significant amounts of energy are lost in feces, used in cellular respiration, and lost to the environment as heat.

Suppose you could change some of these variables in an experimental ecosystem. How would the pyramid of net production change? Remember that in a typical ecosystem, the shape of the pyramid is similar to the one in Part B, and a maximum of 4-5 trophic levels are supported.