Ontario Grade 9 Science Class Practice Exam 2025 – Your Complete Guide to Exam Success!

Autotrophs are organisms that have the ability to produce their own food, primarily through processes like photosynthesis or chemosynthesis. This characteristic distinguishes them from other types of organisms. In photosynthesis, for example, plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen. This process not only provides energy for the autotrophs themselves but also plays a crucial role in supporting the food web by serving as a foundational energy source for heterotrophs—organisms that rely on consuming others for energy.

In contrast, other types of organisms discussed in the options involve different modes of energy acquisition. For example, those that consume other organisms obtain energy by eating them, while organisms that break down dead organic matter participate in decomposition, which recycles nutrients back into the ecosystem. Lastly, individuals that depend on external energy sources are not capable of creating their own food, which is a defining feature of autotrophs. Thus, the ability of autotrophs to synthesize their own food makes them essential players in ecological systems.