How representative is Uworld biochem of AAMC Biochem?

Basically the title. I'm currently getting destroyed by Uworld biochem and I'm not sure why it is so difficult? Did you guys find UWorld biochem harder or easier than the actual MCAT. I just got a 510 on my last AAMC FL, so I don't think it is content gaps. But at this point I'm not sure.

Any MCAT biochemistry advice is much appreciated.

Thanks in advance