Phosphorus and sulfur are returned to the soil primarily by the actions of
A) producers.
B) decomposers.
C) primary consumers.
D) tertiary consumers.

What will MOST LIKELY happen if a new producer is introduced into a food web?
A) The omnivores will decrease.
B) The herbivores will increase.
C) The carnivores will decrease.
D) The decomposers will decrease.


The biosphere is the highest level of organization in the hierarchy of life on earth. Rank the levels of organization from most complex to simplest.
A) ecosystems > communities > populations > organisms
B) organisms > populations > communities > ecosystems
C) ecosystems > organisms > communities > populations
D) populations > communities > ecosystems > organisms