This question is describing the process of cellular respiration. Cellular respiration, which is the process by which organisms obtain their energy (ATP), occurs in stages. The first stage undergone by all living cells is called GLYCOLYSIS.
IN GLYCOLYSIS, glucose molecule (from digested food) is broken down via oxidation in the CYTOPLASM of the cell, into two molecules each of pyruvate, ATP, and NADH. The pyruvate proceeds to the other stages of cellular respiration.
