What is an autotroph?

An autotroph is defined as an organism that can produce its own food through processes such as photosynthesis or chemosynthesis. This characteristic allows autotrophs to convert inorganic substances (like carbon dioxide and water) into organic compounds (such as glucose) using energy from sunlight or chemical reactions. This self-sustaining capability places them at the base of food chains, as they serve as a primary source of energy for heterotrophs, which are organisms that rely on consuming other organisms for sustenance.

In contrast, heterotrophs (the organisms that consume other organisms for energy) depend on autotrophs or other heterotrophs for their nutritional needs. The other options, which involve living off organic materials or decomposing dead matter, pertain to different ecological roles such as saprophytes or decomposers, further distinguishing their function in ecosystems from that of autotrophs. This distinction highlights the unique role of autotrophs in energy production and their foundational importance in ecosystems.