<p>I was accepted for a science degree at Oxford (biochem). But that's probably bc. I had tons of AP classes and a lucky interview. So take AP/IB and work on your speaing skills. ;) Also, I go to a community high school, not one in the top ten.</p>
<p>As for the different systems - it all depends on what you are looking for in higher education and how sure you are of what you want to study. If you are set that a certain subject is definitely your thing, go for it. Like one wise biology teacher once told me, "Nothing is impossible. They fill their undergraduate class with students each year." And some are Americans. Who knows, it might just be you. =)</p>