I do not understand how it is possible for someone with the intelligence necessary to get at least a B in a science course at an accredited institution of higher learning in the United States to score 485 on the MCAT. I mean, isn't that in random guess territory? And you did it twice. Something else must be going on. Are you finishing the test or finding yourself running out of time and answering C to all of the questions that remain on each section? How come whatever it is that's causing you to perform so poorly on the MCAT is not happening when you take your exams in school (otherwise you would have failed out of college)? You need to find out what the answer to that is and develop a long term strategy to solve it.
Here's what could happen without proper MCAT study prep (said student could have A's in science courses).
1. Doesn't remember any chemistry or physics formulas for the first section, has trouble manipulating units on a whim, and doesn't know how to not use a calculator.
2. Either English is 2nd language or isn't good at reading passages for CARS.
3. Poor knowledge of biology terms for BIO sections.
4. underestimating how much psychology/sociology terms you have to know for last section (you have to essentially become an encyclopedia for this section).
Just overall horrendous prep could lead to a 10th percentile on the MCAT, even if the student can earn A's or B's in typical science courses.
My biggest concern for the OP is not improving the score the second time taking the MCAT.
If student earned a 485 on the first attempt, then they should say to themselves "wow, that was really difficult, I was definitely unprepared".
Even having a 486 the second time would show some improvement.
My guess is the OP just isn't studying enough...