Four basic processes that are essential for maintaining life are
Nutrition-it is the process of transfer of energy source from outside to the body of living organisms, providing energy necessary for performing basic life processes like nutrition respiration reproduction extra.
Respiration-it is the process of acquiring oxygen from outside into the body and using it for The breakdown of food sources to release energy for cellular needs.
Transportation-it is the process of carrying food and oxygen from one place to another in the body.
Excretion-it is the process of removing by products and waste products from body which are formed during energy generating reaction.