Humans, octopi and pine trees alike are all made up of cells, tiny but sophisticated systems that keep life going. Cells are almost like tiny factories run by robots, with the nucleus, DNA, proteins, lipids, and vitamins and minerals all... (More)

All living things are made of cells. In the human body, these highly efficient units are protected by layer upon layer of defense against icky invaders like the cold virus. Shannon Stiles takes a journey into the cell, introducing the... (More)

• ecology – the study of living things and their environments
• environment – everything that surrounds a living thing
• community – all populations that live in a certain place
• ecosystem – living and nonliving things in an environment, together with their... (More)