This book is aimed at medical students taking their USMLE step 1 1. Open-ended questions for the USMLE step 1. 2. The book contains 320 biochemistry questions. 3. You will have to know your biochemistry really well to answer these non-multiple choice questions. 4. Designed for students to finish reading the weekend before their test. 5. Affordable price and free future updates by re-downloading subsequent versions.