I bought this book looking for a good passage-based practice for the biology section of the MCAT. From my experience with the book 101 passages in Verbal Reasoning, I was impressed with Examkracker's accurate represenation of real MCAT questions. However, I soon found numerous errors in the questions used in this book, and I confirmed that they were wrong with several physiology and biology professors. From that point, I gave up on the book, because it caused more harm than good.