At my kids’ high school, they go straight into AP sciences without having ever taken high school level Bio, Chem, or Physics. It is possible to take AP levels without having had high school science.
I would suggest that you take the one with the best teacher, with the best reviews. If they are both extremely well taught, know that AP Bio will probably be more interesting, but AP Chem is more useful, because you don’t need Bio to do Chem, but you do need some chemistry to do AP Bio (which will be superficially taught in the AP Bio class). My kids joked that their AP Bio class WAS their high school chemistry class.