Biology Regents Practice Exam

Cells convert glucose into energy primarily through the process known as cellular respiration. This multi-step metabolic pathway allows cells to break down glucose molecules, releasing stored energy in the form of adenosine triphosphate (ATP), which is essential for various cellular activities.

Cellular respiration occurs in several key stages—glycolysis, the Krebs cycle (or citric acid cycle), and oxidative phosphorylation (electron transport chain)—ultimately leading to the production of ATP. During glycolysis, glucose is initially broken down into pyruvate, which then enters the Krebs cycle, facilitating further breakdown and energy extraction. The process also requires oxygen in aerobic respiration, allowing for the efficient production of ATP.

While other processes such as fermentation and glycolysis are related to energy production, they serve specific roles or occur under certain conditions. Fermentation is an anaerobic process that occurs when oxygen is not available, allowing cells to still generate some energy, but it is less efficient compared to cellular respiration. Glycolysis specifically refers to the first stage of cellular respiration where glucose is converted into pyruvate, but it does not encompass the entire energy production process.

In summary, cellular respiration is the comprehensive process that includes the breakdown of glucose, yielding a higher energy output through a