The only exact cutoffs for grades are C- and below for the required classes (that being orgo 1/2 w lab, physics 1/2 w lab, chemistry 1/2 w lab, differing bio classes, as well as various other courses that depends on the school). That being said, competition creates cutoffs but there is a range of schools you can apply to. When you're applying to med schools get the MSAR book or a similar resource and apply to the schools that you have the right gpa for. As long as you have above a 3.0 you can get in somewhere, even if it's a Caribbean school. If you can make it past the weeder classes, don't let grades get in the way of you being a doctor if that's really what you want to do. As for the MCAT, to expand upon what mad4u689 said, I would say first you need to take more than a couple practice tests. In addition to the hundreds of individual practice problems you should be doing, you should probably take 5-15 practice tests. Space them out during your studying duration. And look for patterns in the type of questions you're getting wrong, not necessarily the content you're getting wrong. If you take a class, it will help you a lot with the strategy of the MCAT.