Sorry, I've been in the middle of classes and applications and research and other things.
I did my GRE biochem, and I'll tell you what, the best advise I can give is - keep a clear head be aware AND DON'T FREAK OUT (also, get lots of sleep before the exam).
I didn’t rely a bit on the stuff I learnt a week before the exam. I leaned on prior exam and class experience; also, I found it to be real easy to derive answers to many questions that you would not normally know (using elimination). But most importantly, don't care about problems you can't solve - if a question takes more than 40 seconds to answer, go to the next one. Do all the hard ones at the end.
A little solace I received from my professors about the Biochem exam was that it is considered to be the hardest subject test on the ETS market because of its voluminous content. So, if you do well on the exam, its a BIG one up on others, but if you bomb it, admissions committees normally say "um, its a freaking hard exam, It doesn’t matter".
So, when you go to the exam hall, think of it as a fun challenge rather than an exam one has to face.
Good luck to everyone,
RanjAn