A cell is the smallest unit of living matter that can exist by itself. Some organisms, such as bacteria, are made up of only one single cell. As for other organisms, such as humans and redwood trees, billions of cells are required. That means that those multitudinous cells have to work together to enable people to do things such as walk, talk, and eat, and for trees to send down roots, sprout branches, and grow leaves. Readers of this authoritative...

"It's usually pretty easy to tell if an organism is an animal or a plant at a single glance. Interestingly enough, plant and animal cells are also easy to tell apart. Readers will learn the organelles--cell parts--that are particular to animal or plant cells. They will be exposed to the wide variety of plant and animal cells, as well as the characteristics that makes specialized cells so perfectly suited to their functions. Special attention is paid...