What is known as the sum total of all human life functions?

The sum total of all human life functions is known as metabolism. Metabolism encompasses all the biochemical processes that occur within an organism, which include both the building up of compounds (anabolism) and the breaking down of compounds (catabolism). These processes are essential for maintaining life, as they provide the energy necessary for growth, reproduction, and other vital activities.

Metabolism is a comprehensive term that includes various functions such as digestion, respiration, and energy production, and it is critical for the maintenance of homeostasis— the state of steady internal conditions. Each of the other options represents specific functions or processes within the broader metabolic framework. Digestion, for instance, refers specifically to the breakdown of food into usable components, while respiration pertains to the process of taking in oxygen and expelling carbon dioxide. Homeostasis involves the regulation of internal environments, but it does not encompass all life functions as metabolism does. Therefore, metabolism is the most accurate term for the sum total of all human life functions.