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. The first metabolic stage is the breakdown of proteins, fats and carbohydrates to water-soluble amino acids, mono- and disaccharides, glycerin, fatty acids and other compounds under the action of enzymes in special organs or structures (in unicellular organisms). The second stage of the exchange is the chemical reaction of the synthesis of enzymes, hormones, components of the cytoplasm and the release of energy. The third step is the removal of the final decay products and their removal from the body.
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.