The answer is—it depends.
Some medical schools screen out any applications that have not completed all admission requirements; some don’t.
However, you would be very foolish NOT to take biochemistry before you take your MCAT. The biology portion of the MCAT is 40-45% biochemistry questions. It’s unlikely you would be able to score well on the MCAT without having taken a biochem class.
You’d also be foolish to have NOT taken stats since stats questions are included on all 4 sections of the MCAT.
So the question is: what do you want more:
1 ) to apply to directly to med school from undergrad as part of some arbitrary timeline?
OR
- to have the best chance of scoring well on the MCAT so that you have the best chance of gaining a med school admission?
Again it depends on the individual school policies. (Remember in med school speak recommended = required, if you want to be considered a strong candidate for admission.)