During which process is glucose primarily broken down to yield energy?

The breakdown of glucose to yield energy primarily occurs during cellular respiration. This is a metabolic process where glucose is oxidized to produce ATP (adenosine triphosphate), the energy currency of the cell. Cellular respiration consists of several stages, including glycolysis, the Krebs cycle, and oxidative phosphorylation.

During glycolysis, glucose is split into two molecules of pyruvate, generating a small amount of ATP and NADH in the process. The pyruvate then enters the mitochondria, where it is further processed in the Krebs cycle. Here, energy-rich electron carriers, NADH and FADH₂, are produced, which subsequently participate in oxidative phosphorylation to drive the synthesis of a larger amount of ATP through the electron transport chain.

In contrast, photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose, not its breakdown. Protein synthesis refers to the process by which cells build proteins based on genetic instructions and does not involve the breakdown of glucose. Nitrogen fixation is a process where certain organisms convert atmospheric nitrogen into a usable form for plants but does not relate to glucose metabolism. Thus, cellular respiration is the key pathway for the breakdown of glucose to harness energy, making it