Weegy: A heterotroph is an organism that gets food from outside itself. User: Multicellular organisms have many cells. What is the one other characteristic they must have before they can be called multicellular? A. The cells must be small. B. They must be autotrophs. C. They must be heterotrophs. D. The cells must be specialized. Weegy: They must be heterotrophs. This the one other characteristic they must have before they can be called multicellular. User: What are collections of similar cells called? A. clones B. tissues C. organs D. organisms Weegy: Collections of similar cells are called tissues. User: Why is an amoeba not an animal? A. It is asexual. B. It is unicellular. C. It is prokaryotic. D. It is autotrophic. Weegy: An amoeba is not an animal because: it is unicellular. User: What is the liver an example of? A. a cell B. a tissue C. an organ D. an organ system (More)