a.  

what and which are not semantically related, but they are similar in form, which is also often a feature of blends.

b.  

tree and roof are not semantically related to one another, but tree is obviously from the same semantic field as branch, since a branch is a part of a tree.

c.  

learn and need are not semantically related.

d.  

maid and music are not semantically related to one another, but both are collocationally related to (occur in constructions with) chamber.

e.  

wine and dinner are related through being parts of the same semantic field (to do with eating and drinking, or to do with entertaining).

f.  

players are a type of (hyponym of) people.

g.  

gym and piscine are from the same semantic field, and they are co-hyponyms of (i.e. they are both types of) a superordinate term such as sporting venue.