Allopatric Speciation

These images from the Smithsonian Institution depict Nancy Knowlton's work with snapping shrimp in Panama. Knowlton found that the closing of the isthmus -- dividing the Pacific Ocean from the Caribbean -- resulted in new species of shrimp.

All Systems Are Go

Test your knowledge of the digestive, respiratory, and other human body systems in this interactive game from Kinetic City. Race the clock to put Arnold's organs back into his body one system at a time.

Alzheimer's: Is the Cure in the Genes?

An estimated 15 million Americans will suffer from Alzheimer’s by 2050. QUEST visits with researchers at San Francisco’s Gladstone Institutes who have found that a gene may hold the key to a cure for this debilitating affliction.

Alzheimer's Disease

This video segment from the Secret of Life School Video: "Genetic Medicine: Tinkering with Our Genes" explores the potential for gene therapy to cure diseases like Alzheimer's.

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Amazing Heart Facts

This feature from the NOVA "Cut to the Heart" Web site highlights facts about the heart -- including its size and placement -- and will help you to understand the importance of this wondrous organ in our bodies.

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Amazon Rainforest

This video segment from the Race to Save the Planet teaching module "Saving the Diversity of Life" describes the ecological value of tropical rainforests and explores some of the causes of their destruction.

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American Chestnut Tree

This annotated slideshow adapted from KET's Electronic Field Trip to the Forest illustrates how blight decimated the American chestnut tree and the methods scientists use to identify and pollinate the remaining trees to create blight-resistant trees.

Amphibian Research

This short video segment from IdahoPTV's D4K explains how frogs help biologists study problems in the environment.

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Amphibians

This video segment from IdahoPTV's D4K points out what it means to be cold-blooded. A frog's life cycle is revealed as well as why it croaks, why it hibernates, and how it catches its prey.

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An Alaska Native Community Helps Seals

This video from First Alaskans Institute spotlights the Alaska Native community of St. Paul and its hands-on commitment to care for the land and animals on which it depends.

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Analyzing an Ecosystem

In this interactive activity adapted from the University of Alberta, identify the living and nonliving things in an ecosystem. Then look further at the living things to identify the producers, the consumers, and examples of mimicry.

An Ancient Legend Teaches Climate Change Adaptation

Today’s unsustainable use of natural resources is compared to the legend of the giant Uab, in this video adapted from the Secretariat of the Pacific Community.

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Ancient Farmers of the Amazon

This video segment from Evolution: "Evolutionary Arms Race" tells the story of the leafcutter ant and the fungus it farms -- an example of mutually beneficial symbiosis.

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Anglerfish

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

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Animal and Plant Cell

Think you can tell a yam from a yak? Examine these still images of typical plant and animal cells from Biology by Kenneth R. Miller and Joseph Levine. What similarities and differences can you find?

Animal Babies

This interactive slide show illustrates the variety of animal babies that exist on earth -- some completely independent and others deeply reliant on parental care.

Animal Body Plans: Homeobox Genes

The homeobox genes that define the basic body plan of mice and fruit flies are illustrated in this graphic from The Human Evolution Coloring Book by Adrienne Zihlman. The accompanying article describes how these genes act as "molecular architects" in all animal species.

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Animal Chefs

Ever wonder how to tempt the taste buds of a 400-pound mola mola? In this video from QUEST produced by KQED, learn how the chefs at the Monterey Bay Aquarium prepare meals to feed thousands of species.

Animal Classification Game

Learn about classes of animals and test your ability to identify animals as mammals, birds, reptiles and more in this interactive activity adapted from Sheppard Software.

Are We Alone?

This video segment adapted from NOVA features a variety of scientific perspectives on the age old question, "Are we alone in the universe?" Animations make vivid the improbability that we could intercept a radio wave signaling extra terrestrial intelligence.

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