While there is a core curriculum that is a prerequisite for medical school, certain schools require additional coursework or competencies (like the CASPer exam). The AAMC does a good job of keeping up a database of that information, listed by school. An applicant can sort through to see what each institution requires. You might have to do a little bit of digging once you open a school's link, but the information is usually accessible.
Of note, if a course is required for admission, it's probably best not to take the class on a pass/fail basis.