Organisms can't create the energy they need to live; they must capture it from the environment.
a. true
b. false

Which of the following is an oxidation-reduction reaction? (pictured below)

Depending on the organism the number of in a cell may change

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important