Does getting bad grades in your sciences classes correspond to low MCATS?
I wouldn't say so, no. There have been plenty of people who have done great on their MCAT and had a not-so-great GPA. And vice versa.
They test different things.
Agreed that there are countless counterexamples to a correlation between MCAT scores and GPA.
Not only do they test different things, but they also require different commitments and motivation. GPA takes 3+ years to establish, while the MCAT material could be literally mastered in a few months. Also, the MCAT comes
after a GPA is established, which means many students know they need stellar scores to make up for a subpar GPA. Thus they might study more than most, get super high scores, and provide another counterexample to the GPA/MCAT correlation assumption.
However, any readers should know that if you are not performing well in your science pre-reqs that are tested on the MCAT, it WILL be an uphill battle when preparing for the MCAT. You will have to remediate and learn the things you didn't master in class. You'll need to dedicate a good amount of time for MCAT prep and have the motivation and determination to go above and beyond most of your peers, in order to succeed.
Going the other way (high GPA, low MCAT), many people think they have a lock on the tested material, after doing very well in the pre-req courses. However, the MCAT is at least 50% strategy and testing skills (which
can be learned, despite what some people will say). Thus, many people don't prepare correctly--either due to ignorance or overconfidence--and don't end up doing as well on the MCAT as they might have predicted, based on their high GPA and
obvious academic skills.