I notice that you are a freshman in high school so you still have time to load up on science classes. You will want to take as many science clases that your school offers. You will definately need to take biology and chemistry. Also, if your school offers AP biology and AP chemistry be sure to take those as well. In college as a pre-med student you will take multiple chemistry classes ranging from general chemistry to organic chemistry. Also, get a good background in math, if it is offered take calculus. In college you will have to take two or three classes of physics so again take a physics class in high school. If your school offers any science electives such as anatomy and physiology I would recommend taking them as it is good to get acquainted with bones ,muscles, etc. early on in your studies. This may seem like a lot of science to fit into your four years of high school, but it is doable. In the end having a good science background in high school will prepare you for your college classes.