AFAA Personal Trainer Certification Practice Exam

Which metabolic process is responsible for breaking down carbohydrates into energy?

1. Glycolysis

2. Krebs cycle

3. Beta oxidation

4. Electron transport system

The correct answer is: Glycolysis

The metabolic process responsible for breaking down carbohydrates into energy is glycolysis. This process occurs in the cytoplasm of cells and is the initial stage of carbohydrate metabolism. During glycolysis, a molecule of glucose is enzymatically split into two molecules of pyruvate, generating a small amount of ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide). Glycolysis serves as a fundamental pathway for energy production, especially during high-intensity exercise or when oxygen availability is limited. It does not require oxygen, making it an anaerobic process. This characteristic allows for quick energy production, which is essential during short bursts of activity. The other processes mentioned, while also important for energy production, pertain to different aspects of metabolism. The Krebs cycle (also known as the citric acid cycle) primarily functions in aerobic conditions and occurs in the mitochondria, processing the pyruvate produced by glycolysis. Beta oxidation specifically refers to the breakdown of fatty acids into acetyl-CoA for use in the Krebs cycle. The electron transport system is the final stage of cellular respiration where ATP is produced through oxidative phosphorylation, utilizing the electrons carried by NADH and FADH2 generated in earlier metabolic processes