Emergency Medical Technician (EMT) Intermediate Practice Exam

What metabolic process occurs when oxygen levels are low or absent?

1. Aerobic metabolism

2. Fermentation

3. Anaerobic metabolism

4. Lipid metabolism

The correct answer is: Anaerobic metabolism

When oxygen levels are low or absent, anaerobic metabolism is the metabolic process that comes into play. In contrast to aerobic metabolism, which requires oxygen to efficiently convert glucose into energy (ATP), anaerobic metabolism allows cells to generate energy without oxygen. This process typically results in the production of energy in smaller amounts and can also yield byproducts such as lactic acid in animals, which can lead to muscle fatigue. While fermentation is a specific type of anaerobic metabolism, the term "anaerobic metabolism" encompasses a broader range of processes that take place in the absence of oxygen. Lipid metabolism and aerobic metabolism both require oxygen and are not applicable under low or absent oxygen conditions. Thus, anaerobic metabolism is crucial in situations where oxygen is limited, allowing organisms to continue producing energy to maintain vital functions despite the lack of oxygen.