Sketching Bloch functions

Jenkz

Wave functions of a Kronig-Penny model with the limit (Uo →∞) are considered in this question. The wave functions for k=0, k=1/2, k=[itex]\pi[/itex], k=2[itex]\pi[/itex] in the lowest energy band are sketched.

I don't quite understand how these were sketched. I have attached the graphs on here, could anyone please explain?

Thanks.

Attached Thumbnails