Essential is related to Must. Must is the opposite of Should. Should have Bed. Bed is related to Sack. 
Culture is a type of Grow. Grow is related to Big. Big is a synonym of Prominent. 
Essential <--RelatedTo--> Must <--Antonym--> Should --HasA--> Bed <--RelatedTo--> Sack 
Culture --IsA--> Grow <--RelatedTo--> Big <--Synonym--> Prominent 