The commentary tells us that like all living things, they react to their surroundings, grow, reproduce, feed and get rid of waste. They need air, too. These characteristics are contrasted with ...

What are these living units called cells ... sometimes as part of complex multicellular organisms. Cells also differ in size. Although cells can be quite large — consider a frog's egg, for ...

What are these living units called cells ... sometimes as part of complex multicellular organisms. Cells also differ in size. Although cells can be quite large — consider a frog's egg, for ...