A. review what are the two primary sources of energy that power living systems? b. pose questions propose a question that a scientist might ask about the variety of organisms found around deep-sea vents. 7.a. review explain how consumers obtain energy. b. compare and contrast how are detritivores different from decomposers? provide an example of each. 8.the word autotroph comes from the greek words autos, meaning "self," and trophe, meaning "food or nourishment." knowing this, what do you think the greek word heteros, as in heterotroph, means?