Cellular respiration involves which of the following energy sub-pathways?

The correct response identifies the main sub-pathways of cellular respiration: glycolysis, the Krebs cycle (also known as the citric acid cycle), and the electron transport chain.

Glycolysis is the initial stage of cellular respiration that occurs in the cytoplasm, where glucose is broken down into pyruvate, producing a small amount of ATP and NADH in the process. This step does not require oxygen and serves as a crucial preparatory phase for the further oxidation of glucose.

Following glycolysis, in the presence of oxygen, pyruvate enters the mitochondria, where the Krebs cycle takes place. This cycle further processes the pyruvate to release carbon dioxide and generate energy-rich molecules, including NADH and FADH2, which carry high-energy electrons to the next stage of respiration.

The electron transport chain occurs in the inner mitochondrial membrane, utilizing the electrons from NADH and FADH2 generated in previous steps. This stage produces the majority of ATP during cellular respiration through oxidative phosphorylation, where oxygen acts as the final electron acceptor and combines with electrons and protons to form water.

Understanding these sub-pathways is crucial, as they form the basis of how cells convert biochemical energy from nutrients into ATP, the energy currency