An organism that uses sunlight or inorganic substances to produce food?

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

Answer: (A)

Autotrophs produce their own organic matter from inorganic sources by harvesting energy either from sunlight or from inorganic chemical reactions. Photoautotrophs, like plants, algae, and cyanobacteria, use light energy to drive photosynthesis, turning carbon dioxide and water into sugars. Chemosynthetic autotrophs, such as certain bacteria, derive energy from inorganic molecules (for example, hydrogen sulfide) to fix carbon into organic compounds. This makes them the base of ecosystems, providing the biomass that heterotrophs rely on for food. The other groups don’t synthesize food from inorganic energy: heterotrophs need preformed organic matter from others, omnivores eat a mix of plant and animal material, and decomposers break down dead material to recycle nutrients rather than creating new biomass from inorganic energy.