Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

Autotrophs are organisms that can produce their own food through processes such as photosynthesis or chemosynthesis. This ability allows them to convert inorganic substances into organic compounds without relying on other organisms for sustenance. Plants are classic examples of autotrophs because they use sunlight to convert carbon dioxide and water into glucose and oxygen, a process facilitated by chlorophyll and other pigments. This process not only provides energy for the plants but also contributes oxygen and organic materials to the ecosystem, forming the base of food webs.

In contrast, herbivores and carnivores are heterotrophs, as they consume other organisms for energy. Decomposers, while crucial to nutrient cycling, break down dead organic matter and cannot produce their own food. Thus, the defining characteristic of autotrophs is their ability to synthesize food independently, making plants the primary example of this group.