Which type of organisms obtain food from other organisms?

• A. Autotrophic
• B. Heterotrophic
• C. Saprotrophic
• D. Chemotrophic

Answer: (B)

The key idea is how organisms obtain their organic nutrients. Those that rely on consuming or absorbing nutrients from other organisms are heterotrophs. They cannot make their own organic molecules from inorganic sources, so they depend on pre-formed food produced by others. This includes animals, fungi, and many bacteria.

Autotrophs, by contrast, make their own organic matter—often using light energy in photosynthesis or chemical energy in chemosynthesis—so they don’t obtain food from other organisms. Saprotrophs are a type of heterotroph that feeds on dead or decaying organic matter by external digestion, which is still feeding from material produced by other organisms, but the broader category used here is heterotrophic. Chemotrophic describes how they obtain energy, not strictly where their carbon-containing food comes from, so it isn’t the best label for “obtaining food from other organisms.”