if you can take any year-long course out of sequence, i would. it helped me out a lot, and my senior year ended up being a breeze. i had taken all 4 big subjects (chem, phys, orgo, and bio) by the end of junior year when i first took the mcat.
i took chem freshman year, in sequence
then i started with bio 2 at the end of freshman year, and bio 1 at the beginning of sophmore year, while takine physics in sequence.
my intro bio courses didnt really correlate w/ each other, which is why i was able to take them out of order. and i think that now intro bio is 3 semesters at my school, hehe suckers!