Which term describes an organism that obtains its energy from abiotic sources such as sunlight or inorganic chemicals?

• A. Autotroph
• B. Heterotroph
• C. Consumer
• D. Decomposer

Answer: (A)

The main idea is that some organisms make their own energy using energy sources that aren’t derived from other organisms. Autotrophs do exactly this: they capture energy from abiotic sources—light in photoautotrophs or inorganic chemical reactions in chemoautotrophs—and use that energy to convert inorganic carbon, like carbon dioxide, into organic molecules. This ability to synthesize organic matter from inorganic inputs places autotrophs at the base of most ecological food webs.

Heterotrophs, by contrast, obtain energy by consuming organic compounds produced by others, and decomposers break down dead organic material. While those processes rely on organic matter, autotrophs operate independently of living helpers for their energy source, which is why autotroph is the correct term.