Explore biology topics with Khan Academy, offering free resources to learn about cells, genetics, evolution, ecology, and more.

Unit 1: Intro to biology About this unit This unit is part of the Biology archive. Browse videos and articles by topic. For our most up-to-date, mastery-enabled courses, check out High School Biology and AP …

Learn AP Biology using videos, articles, and AP-aligned multiple choice question practice. Review the fundamentals of biochemistry, cell biology, genetics, evolution, and ecology, and develop scientific …

Science Middle school biology Learn biology using videos, articles, and NGSS-aligned practice. Review the fundamentals of cell biology, organism growth and reproduction, photosynthesis, cellular …

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Chemistry is the study of matter and the changes it undergoes.

Learn high school biology using videos, articles, and NGSS-aligned practice. Explore the fundamentals of cells, organism growth and development, photosynthesis and cellular respiration, molecular and …

Learn about restriction enzymes and DNA ligase in DNA cloning with Khan Academy's comprehensive tutorial.

The Gibbs free energy change (ΔG) and how it's related to reaction spontaneity and equilibrium.

Key points: DNA cloning is a molecular biology technique that makes many identical copies of a piece of DNA, such as a gene. In a typical cloning experiment, a target gene is inserted into a circular piece …