ABSTRACT
Animals are mainly herbivores. Certain species, such as cows, can
digest carbohydrate cellulose and change it into nutrients. Humans
are mainly dependent on an intake of carbohydrates in the form of
sugar and starch, but also need protein, carbohydrate, vitamins,
minerals, etc. Humans and animals depend entirely on air for respiration. Oxygen
enriches the blood and makes the body capable of burning food in an
exothermic reaction releasing heat, approximately 80-150 W for an
adult human being, depending upon the level of activity.