Does the closure of a function include the actual parameter passed to the function?
No. A closure is a function, and, as such, its parameters are passed when the function is called. The main difference between closures and plain functions is that closures are associated with an environment. This environment stores the values of the free variables* that were in scope when the function was created.

* The term free variable refers to those variables which are used locally within a function but are defined outside of this function (i.e., in an enclosing scope).