Species is related to Boy. Boy is a synonym of Mate. Mate is related to Term. Term is related to Memory. 
Valley is related to Depression. Depression is related to Condition. Condition is related to Slope. Slope is related to Ladder. 
Species <--RelatedTo--> Boy <--Synonym--> Mate <--RelatedTo--> Term <--RelatedTo--> Memory 
Valley <--RelatedTo--> Depression <--RelatedTo--> Condition <--RelatedTo--> Slope <--RelatedTo--> Ladder 