The sum total of all the chemical reactions occurring in our body known as

The correct option is Metabolism.

Metabolism is the scientific term used to describe the sum total of all the chemical reactions that take place within the cells of a living organism to maintain life. These biochemical processes allow organisms to grow, reproduce, maintain their structures, and respond to their environments.

To understand why this is the correct answer, we can break down the options:
1. Anabolism: This refers to the metabolic pathways that construct molecules from smaller units. These reactions require energy (for example, the synthesis of proteins from amino acids).
2. Catabolism: This refers to the metabolic pathways that break down molecules into smaller units. These reactions release energy (for example, the breakdown of glucose during cellular respiration).
3. Amphibolism: This term is used to describe a biochemical pathway that involves both anabolism and catabolism (for example, the citric acid cycle).
4. Metabolism: This is the overarching term that encompasses both anabolic (building up) and catabolic (breaking down) processes. Therefore, the sum total of all these chemical reactions occurring in our body is known as metabolism.