This animation shows how the proton gradient across the mitochondrial membrane powers the ATP synthase enzyme to make ATP. It is the third 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 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.

In this activity, students learn about the factors that regulate the population sizes of wildebeest and buffalo in Serengeti National Park.

This activity allows students to formulate and analyze scientific questions.

This video follows biologist Shane Campbell-Staton, who is studying the adaptations that allow deer mice living at high elevations to stay warm and active during the winter.

In this activity, students explore using CRISPR-Cas9 to knock out butterfly genes in order to determine their function. 

In this activity, students analyze aspects of a scientific paper that investigates genes involved in the colors and patterns of butterfly wings.

This film explores the foundational research in the Serengeti National Park, Tanzania, that uncovered many of the ecological principles that govern how animal populations and communities are regulated.

This film explores the species-area relationship, a general ecological rule that describes how the number of species in a habitat changes with area, and shows how it has been applied to the conservation of protected areas.

This multipart animation series explores the process of photosynthesis and the structures that carry it out.

This data-driven activity accompanies the video Selection for Tuskless Elephants. It engages students in analyzing data to make evidence-based claims about the occurrence of tusklessness in elephant populations.