1) At the preparatory stage, complex organic substances are broken down to less complex ones, for example biopolymers, to monomers.
2) In the process of glycolysis, glucose is broken down to pyruvic acid (or lactic acid, or alcohol) and 2 ATP molecules are synthesized.
3) At the oxygen stage, pyruvic acid (pyruvate) is broken down to carbon dioxide and water and 36 ATP molecules are synthesized.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.