Ontario Operator-in-Training (OIT) Practice Exam

What do anaerobic microorganisms require for survival?

1. Avoidance of oxygen

2. Direct sunlight

3. High temperatures

4. Presence of oxygen

The correct answer is: Avoidance of oxygen

Anaerobic microorganisms thrive in environments where oxygen is absent. These organisms have adapted to utilize alternative forms of energy and can survive and grow in low-oxygen or completely anoxic conditions. The requirement for avoiding oxygen is essential because exposure to oxygen can lead to the production of toxic byproducts or oxidative stress, which can be lethal to these microorganisms. This adaptation is crucial for their survival, particularly in environments such as deep soils, sediments, and the human gastrointestinal tract, where oxygen levels are minimal to nonexistent. In contrast, direct sunlight, high temperatures, and the presence of oxygen are factors that either do not apply or are detrimental to the survival of anaerobic microorganisms, highlighting the unique ecological niches they occupy.