This animation shows the reactions of the citric acid cycle, which splits off carbon atoms and generates energy-rich reduced forms of cofactor molecules. It is the first of three animations about cellular respiration.
This animation shows how the enzyme complexes of the electron transport chain harvest energy from cofactor molecules to pump protons across the mitochondrial membrane and establish a chemical gradient. It is the second of three animations about cellular respiration.
This interactive module allows students and educators to build models that explain how the Earth system works. The Click & Learn can be used to show how Earth is affected by human activities and natural phenomena.
This activity accompanies the video Seed Dispersal and Habitat Fragmentation. Students use data from published studies to understand patterns of seed dispersal and apply these ideas to the design of a conservation area.
This activity supports the film Popped Secret: The Mysterious Origin of Corn. Students analyze data on the expression of the tb1 gene to explain how variations in this gene played a role in the evolution of corn.