Final answer:
Autotrophs can synthesize their own food from inorganic substances like CO₂, mainly through photosynthesis, while heterotrophs need to consume organic matter produced by autotrophs for their carbon and energy needs.
Step-by-step explanation:
The correct distinction between autotrophs and heterotrophs lies in how they obtain carbon and energy for their metabolism. Autotrophs are organisms that produce their own food from inorganic substances such as carbon dioxide through the process of photosynthesis, thus acting as producers in the ecosystem. They capture solar energy and convert it into chemical energy stored in carbohydrates. Examples include plants, algae, and some bacteria.
In contrast, heterotrophs cannot make their own food; they must consume other organisms or organic matter to obtain energy and carbon. This makes them consumers in the food chain. Heterotrophs include all animals, fungi, and many bacteria and protists. They rely directly or indirectly on the organic compounds produced by autotrophs for their nourishment.
Therefore, a key difference is that autotrophs are capable of synthesizing their own food from inorganic materials, while heterotrophs must ingest preformed organic material. This difference is fundamental to understanding food chains and energy flow in ecosystems, with autotrophs serving as the primary producers and heterotrophs functioning as consumers at various levels.