I had a similar question but for a different reason. Besides GPA, MCAT is critical, and to score high, one HAS to be an excellent tester prior to entering college, i.e., 650+ SAT-M. If your son’s score is much lower than that, I’d consider a different major (Bio majors have few job opportunities) and different career (not premed), as the odds of a low-scoring student getting accepted into med school are almost nil.