Essential is related to Blood. Blood is related to Sweat. 
Scientist is a type of Researcher. you are likely to find Researcher in/at/on Laboratory. you are likely to find Monkey in/at/on Laboratory. 
Essential <--RelatedTo--> Blood <--RelatedTo--> Sweat 
Scientist --IsA--> Researcher --AtLocation--> Laboratory <--AtLocation-- Monkey 