Describes the characteristics of Archaea, Bacteria, and Eukarya, the three domains of life.

In this online biology textbook, learn about the two prokaryotic domains of life, which include eubacteria and acrhaebacteria.

This video segment adapted from NOVA goes on a whimsical journey in search of life forms thriving in extreme conditions on Earth and in outer space. Animations show ice on Jupiter's moon, Europa, and signs that water once existed on...

Travel deep into the human body to see exactly where your DNA resides. From the NOVA: Cracking the Code of Life Web site.

This illustrated timeline from the NOVA Web site follows Albert Einstein's life, including 1905, his "Miracle Year," during which he developed his Special Theory of Relativity and the equation, E=mc2.

This series of images shows the work of biologist Karl Niklas on the adaptations and evolution of plants. From The Evolutionary Biology of Plants.

All animals develop and grow over time. The animals in this document undergo one of the most dramatic developmental processes known, metamorphosis. See if you can place the developmental stages in their proper order.

College-level instructor's notes describing taxonomy. Explanations and images give a chronological history of the science of classifying organisms.

Interact with this world map from McDougal Littell/TERC to highlight different climate zones and see a photograph of each one. Ten climate zones are represented, including tundra, desert, humid subtropical, and others.

In this video segment from The Secret of Life school video, "Sex and the Single Gene" follow as a single fertilized egg cell divides, differentiates, and assembles into the tissues and organs of a new organism. [1:20]

This video segment from NOVA: "Cracking the Code of Life" looks at one of the key players in the race to decode the human genome.

This video segment from the Secret of Life School Video: "On the Brink: Portraits of Modern Science" explores the genetics of breast cancer. [3:40]

This video segment from NOVA: "Cracking the Code of Life" explores the genetic similarities and differences among organisms.

Explore the diversity of the domain Archaea.

This collection of six images captures the magnificence of human development -- the transformation from baby to woman.

In this video segment from The Secret of Life, watch as a virus attacks a cell, and learn how the immune system reacts to this onslaught. Includes background reading material and discussion questions. [1:40]

This short video explains how warmer temperatures in the Arctic are transforming the ecosystem and affecting the Athabaskan people, threatening their way of life. [2:59]

See how the human heart moves blood through the body in this animated feature from the NOVA: "Cut to the Heart" Web site.

This video segment from NOVA: "The Shape of Things" follows the growth of a duck embryo, from a single fertilized egg cell to a complex, hatching duckling. [2:43]

This video segment from Evolution: "Why Sex?" explores the "sweaty T-shirt experiment," which showed that humans may unconsciously be drawn toward a specific kind of genetic variation in a mate.

This interactive feature from the NOVA: "Leopards" Web site presents a wide variety of ways in which animals use coloration to their advantage.

This video segment from NOVA: "Animal Imposters" shows the lightning-fast strike of the anglerfish. [1:30]

Which part of your brain controls your ability to swallow? Your instinct to survive? And how do all the brain's parts function cooperatively? Find out with this interactive feature from the NOVA: "Coma" Web site.

It takes a thick skin to withstand the hardships that life has to offer. This collection of images shows a variety of animals, each with a slightly different type of protective covering.