Mine were the other way around, I did better on the later exams! I think that's because in Unit 1 I had 0 interest in science, so really just didn't bother too much and ended up messing up C1 while only just scraping an A* with the other two... Unit 2 went better, but I feel Unit 3 went pretty well too so I'm hoping for a decent grade in them
I think out of the Unit 3 exams Physics was probably the tougher one though thinking back!
Coursework went great for Physics, good for Chemistry, but Biology I really have no clue!