Tennessee Wastewater Operator Practice Exam

Heterotrophic bacteria obtain both their energy and carbon from which source?

1. Inorganic compounds

2. Sunlight

3. Biodegradable organic material

4. Atmospheric nitrogen

The correct answer is: Biodegradable organic material

Heterotrophic bacteria are organisms that cannot produce their own food through photosynthesis or chemosynthesis. Instead, they depend on organic materials in their environment to survive. The correct choice, biodegradable organic material, serves as both an energy source and a carbon source for these bacteria. When they break down organic substances, they release energy through metabolic processes and incorporate carbon from these materials into their cellular structures. In contrast, options such as inorganic compounds represent a source for autotrophic organisms, which can create their own food from inorganic substances. Sunlight is primarily utilized by photosynthetic organisms that convert solar energy into chemical energy. Atmospheric nitrogen is crucial for certain bacteria involved in nitrogen fixation, but it is not a carbon source or an energy source for heterotrophic bacteria. Thus, the dependence on biodegradable organic material clearly defines the nutrition and energy mechanisms of heterotrophic bacteria.