The Ultimate Illustrated Guide for Nonscientists Science 101: Biology provides all the basics of biology in twelve easy chapters, ranging from such fundamental questions as "What is life?" to the essentials of anatomy, physiology, ecology, genetics, and evolution. This book also covers public controversies such as stem-cell research and intelligent design theory.
It's a high school or college level text that could be used in an "Intro to Biology" course. It's a great refresher for anyone who hasn't studied Biology in a while. Although it provides many detailed examples, it takes a "big picture" perspective on the subject. It includes a lot of great photographs and illustrations.