The organism that cannot make its own food and must feed on other organisms for energy and nutrients is called a heterotroph.

Here's why:

* Autotrophs are organisms that can produce their own food through processes like photosynthesis (using sunlight) or chemosynthesis (using chemicals). Examples include plants, algae, and some bacteria.

* Heterotrophs rely on consuming other organisms, either living or dead, to obtain the energy and nutrients they need. Examples include animals, fungi, and most bacteria.

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