modular design

one of design principles  is modular design

ie, with a set of standard parts is conceived with which different designs of products can be done easily

this is in nature too in living beings , including trees

in civil engg construction to design a house, all the parts like  doors windows sanitary fittings , shelf s etc are standardized

in trees like sugar cane. or bambus the total length is composed of small modules

in human beings too each individual is different but thesame standard parts hands legs head eyes etc