To maintain body weight and growth of any organism, it is necessary to obtain proteins, fats and carbohydrates, vitamins, mineral salts, water from the environment. Metabolism begins with the intake of nutrients and gases. For example, at the initial stage of metabolism, protein breakdown occurs under the action of enzymes in special organs (stomach, small intestine) or structures (in unicellular organisms) to amino acids with energy release. The next stage of the exchange is the chemical reaction of the synthesis of own proteins, enzymes, hormones and other protein structures using energy.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.