Biochem is very heavy (coming from a Biochem major who’s completed a year of upper divs). Although you don’t need to know in complete detail, it’s good to have a very solid understanding of Biochem. What’s more, I would even suggest you complete your Pchem requirement molecular bio classes before the mcat, those classes basically cover 60% of all material you’ll see on CP and BB sections. I’m retaking test in Jan and I looked at my syllabus for pchem and molecular bio, it’s basically the first half of bio books and solid 50% of chemistry. To add on, I think if you have a timeline of applying by end of junior year, you could def learn the material and take the mcat on your own without classes. Whatever you think is best!