Should I block my facebook account?

I am applying to a course in Quantitative Finance in a prestigious university in Europe.

I am wondering if it may be the case to block my facebook account; I don't want the commission to look at my profile or to gather information on me that I am not willing to give them directly.

I know that there are probably rules so that you can't discriminate based on age, sex, religion and stuff, but facebook accounts contain far more than that.

So I guess my questions are: Is it common for university to look at candidate's profile before accepting them? If it is, how much does this influence the decision? Can my reluctance to give away some (personal) information be perceived negatively?