This is a good book for biology content review. There are many problems for the 20 chapters. Each chapter covers a different biology topic and there are about 60 questions per chapter so you can thoroughly practice each topic. However all the questions are stand alone ones which are in the minority in the MCAT. This book would have been better if it contained some passage-based questions (with a few passages) for each chapter. Regardless it is a good practice to test your knowledge of all the biology topics listed on the AAMC biology topic list. The explanations are often highly detailed with reasons why certain answer choices are wrong which improved my knowledge even when I got a question correct. I would recommend it to those who need MCAT biology practice.