Kaplan Nursing Entrance Practice Exam

What is the primary purpose of the Krebs cycle in cellular respiration?

1. Storing glucose

2. Producing oxygen

3. Transforming glucose into ATP

4. Generating carbon dioxide

The correct answer is: Transforming glucose into ATP

The primary purpose of the Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle (TCA cycle), in cellular respiration is indeed to transform glucose into ATP. This cycle plays a crucial role in cellular metabolism by facilitating the breakdown of carbohydrates, fats, and proteins into carbon dioxide and energy. During this process, the Krebs cycle occurs in the mitochondria and generates high-energy molecules, including NADH and FADH2, which are critical for the electron transport chain. Through a series of enzymatic reactions, these coenzymes capture and store energy derived from the oxidation of acetyl-CoA (which is derived from glucose and other substrates). The ATP generated during these metabolic processes is essential as it serves as the main energy currency in the cell, powering various cellular functions. While generating carbon dioxide is a byproduct of the Krebs cycle, and could be seen as an important outcome, it is not the primary purpose. Similarly, oxygen plays a role in aerobic respiration but is not produced by the Krebs cycle itself; rather, it is utilized in the electron transport chain. The storage of glucose is also not a function of the Krebs cycle as glucose is broken down rather than stored. Thus, the primary