Contrary to what you might have heard before, MCB 100a is actually pretty interesting and you can do pretty well in it, if you try to focus on the concept, instead of just restorting to pure memorization. (I took it with Prof. Wemmer.) I was also taking couple of other science classes that semester too. I won't say it's the hardest class in MCB, but you do have to spend more than just a couple of hours studying for that class in order to do well.