Definitely possible. In my case a high VR balanced out an average BS and PS for a 30. I have yet to take any college level organic chemistry or biology/zoology/micro/biochem/genetics/anatomy courses.
Biology passages are definitely related to VR, and if you are decently read in science journals/books you can do well on the biology passages. I studied organic on my own to prepare, but it had been 10 years since I had general chemistry and
nothing really made much sense (that chem also hurt my PS score... physics is a strong suit). I tried to memorize reactions, products, names etc. but about the only thing I actually learned well was the IUPAC system... and didn't have any of that on my form.
FWIW, I did a lot better in AAMC practice tests on BS and PS (especially PS) than I did on the August MCAT. VR has been very consistent on all practice tests and the MCAT.
But to answer what I think the intention of the question was... I don't think any but the most genius could score 30+ on the MCAT without at least
studying the subject material. I don't think you could only study "test taking tips and shortcuts" type of stuff, ignore the actual science subjects, and do that well. Even with a 15VR you'd have to score 7/8 on the sciences... that's getting well over half of the questions correct. Possible for the biology if someone has a great memory from high school and is excellent in VR, but IMO not for the physical sciences. That stuff you just have to learn. Not even Newton would have enough time to derive equations from scratch on the MCAT as needed... you have to know them going in. Not for every passage, but for enough to make a good score unlikely.
A true genius... possible. Maybe. But you'd probably find that they had learned/read/studied physics, chem, and biology on their own time and in their own way at some point in their life.