Plant is related to Nature. Nature is related to Science. Science is related to Discovery. Discovery is related to Educational. 
Doctor is related to Health. Health is related to Shape. Layer is a type of Shape. 
Plant <--RelatedTo--> Nature <--RelatedTo--> Science <--RelatedTo--> Discovery <--RelatedTo--> Educational 
Doctor <--RelatedTo--> Health <--RelatedTo--> Shape <--IsA-- Layer 