In the process of evolution, a gradual complication of the organization of living matter took place, and as the next level was formed, the previous one entered into it as an integral part. As a result, the world of living creatures that surrounds us is a combination of biological systems of varying degrees of complexity. This necessitates the allocation of various levels of organization of living matter. It is also extremely important that the combination of several systems belonging to the same level (for example, cells) gives not just the arithmetic sum of their properties. There is a rise to a qualitatively higher level, and the new system has expanded capabilities and abilities (tissue, multicellular organism).
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.