Yolk (Noun)  = The yellow portion of the egg. 
Synonyms:  Vitellus, Nucellus. 
Example:  The yolk of the neck is nutritious.  
Yoke (Noun)  = Bondage. 
Wooden structure put onb a bullock's neck. 
Synonyms:  Burden, Chain, Knot, Ligament, Nexus.  
Example:  They work under the yoke of slavery.