There's a University of Pennsylvania study that seems to make the rounds every now and again about the fact that discipline and hard work enable students to outperform those with higher IQs. The Boston Globe ran a fairly detailed article about the study and others that point to success coming from perserverance and practice as much as intelligence.
As high school students begin their exams and look ahead to college, it's important for them to remember that the grit gene is just as important as the smart gene. Consistency is not simply a virtue. Often, it's also a game winner.