Perhaps you're looking at a different book. KAPLAN does NOT cover biochem. What may seem like biochem to you are in fact topics related to organic chemistry (Amino Acids, etc.). You might end up seeing 1 question out of 30 o-chem question on this topic (if any at all). So, there's no reason whatsoever one would want to waste his/her time, energy, and money on taking a fullblown biochem course just to be able to answer a single question. Taking biochem over physio is simply madness and a great way to mess up the bio section of the exam, while gaining no additional knowledge for the o-chem section.