Body growth begins at the cellular level. From the start of life to the growth spurts of teens, it's the tiny, basic units of life that make everything people do possible. Much about our cells and DNA is the same, but each person on Earth has unique traits, including fingerprints and the configuration of facial features. Readers investigate these similarities and differences in detail, learning about gene expression and how bodies change as people grow from children to adults. Full-color photographs and graphic organizers illustrate important biology concepts such as the systems of the body.