Question

there should not be randomness at any step of reaction in human body

Answer 1

Metabolic reactions are chemical reactionsthat occur within the body to release useable energy. ... During cellular metabolism, the molecule glucose combines with oxygen and reacts to form carbon dioxide and water, as well as ATP, which is a form of energy that thebody can use for its functions.

Answer 2

Metabolic reactions may be categorized as catabolic - the breaking down of compounds (for example, the breaking down of glucose to pyruvate by cellular respiration); or anabolic - the building up (synthesis) of compounds (such as proteins, carbohydrates, lipids, and nucleic acids).