A cell is an elementary structural and functional unit of all living things. Cells exist as independent units (protists, bacteria) and as part of multicellular organisms. In a multicellular organism, cells interact with each other and perform a strictly defined type of activity. The combination of specialized cells allows the body to function successfully in those situations in which single cells are doomed to death.
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.