Emergency Medical Technician (EMT) Intermediate Practice Exam

What are the primary fuels for cellular metabolism?

1. Proteins and fats

2. Vitamins and minerals

3. Glucose and oxygen

4. Carbohydrates and water

The correct answer is: Glucose and oxygen

The primary fuels for cellular metabolism are glucose and oxygen. Glucose, a simple sugar, is a key energy source for cells. It undergoes a series of biochemical processes, including glycolysis, the citric acid cycle, and oxidative phosphorylation, to produce adenosine triphosphate (ATP), which is the energy currency of the cell. Oxygen plays a crucial role in aerobic respiration, a process that allows cells to extract a significant amount of energy from glucose. During this process, glucose is oxidized, and in the presence of oxygen, a large yield of ATP is produced compared to anaerobic methods, which do not utilize oxygen. While proteins and fats are also important for energy, they are typically used after carbohydrates. Vitamins and minerals do not directly serve as fuels but instead act as coenzymes and cofactors in metabolic reactions. Carbohydrates are indeed a source of energy, but they are often broken down into glucose for metabolism, and water is not a fuel but essential for numerous biochemical processes. Thus, the combination of glucose and oxygen is essential for effective cellular metabolism.