Cop is related to Policeman. Policeman is related to Ball. Ball is related to Sphere. Sphere is a synonym of Realm. 
Flower is related to Plant. Plant is related to Biological. 
Cop <--RelatedTo--> Policeman <--RelatedTo--> Ball <--RelatedTo--> Sphere <--Synonym--> Realm 
Flower <--RelatedTo--> Plant <--RelatedTo--> Biological 