Has/will Gibbon look at course prerequisites? Example you can’t take CHEM101 till you’ve completed CHEM102.
Do the courses currently have a completion flag?
Or rather “you can’t take CHEM102 till you’ve completed CHEM101” sounds better, 
There aren’t any plans to add this type of functionality. The course selection module would be the likely place for this type of data to be useful, if a developer were to look at adding prerequisites.