By GK, I am assuming you are referring to General Knowledge. Correct me if I'm wrong.
It's difficult to concentrate in college, especially with all the fun social events going on around you. I'd say it's a good idea to establish a routine for yourself - outside of going to class. Find somewhere quiet and tidy to do your homework; if your living situation is too distracting, you might try the library.
Additionally, make sure to eat a balanced diet and exercise regularly - both of these factors have been shown to have a positive effect on concentration.