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Biology library

Welcome to the Biology library!

Biology is the study of life. Here, you can browse videos, articles, and exercises by topic. We keep the library up-to-date, so you may find new or improved content over time.

Unit 1: Intro to biology

Welcome to biology!: Intro to biologyThe science of biology: Intro to biologyWater and life: Intro to biology

Unit 2: Chemistry of life

Elements and atoms: Chemistry of lifeElectron shells and orbitals: Chemistry of lifeChemical bonds and reactions: Chemistry of life

Unit 3: Water, acids, and bases

Hydrogen bonding in water: Water, acids, and basesCohesion and adhesion: Water, acids, and basesTemperature and state changes in water: Water, acids, and bases
Acids, bases, and pH: Water, acids, and bases

Unit 4: Properties of carbon

Carbon: Properties of carbonHydrocarbon structures and functional groups: Properties of carbon

Unit 5: Macromolecules

Introduction to macromolecules: MacromoleculesCarbohydrates: MacromoleculesLipids: Macromolecules
Nucleic acids: MacromoleculesProteins: Macromolecules

Unit 6: Elements of life

More about macromolecules: Elements of life

Unit 7: Energy and enzymes

Energy in metabolism: Energy and enzymesLaws of thermodynamics: Energy and enzymesFree energy: Energy and enzymes
ATP and reaction coupling: Energy and enzymesIntroduction to enzymes: Energy and enzymesEnzyme regulation: Energy and enzymes

Unit 8: Structure of a cell

Introduction to cells: Structure of a cellProkaryotic and eukaryotic cells: Structure of a cellTour of a eukaryotic cell: Structure of a cell
Extracellular structures and cell-cell junctions: Structure of a cell

Unit 9: More about cells

Cell movement: More about cellsCell size: More about cellsProkaryotes and eukaryotes: More about cells

Unit 10: Membranes and transport

The plasma membrane : Membranes and transportDiffusion and osmosis: Membranes and transportPassive transport: Membranes and transport
Active transport: Membranes and transportBulk transport: Membranes and transport

Unit 11: More about membranes

Cell membranes: More about membranesTransport: More about membranes

Unit 12: Cellular respiration

Introduction to cellular respiration: Cellular respirationSteps of cellular respiration: Cellular respirationGlycolysis: Cellular respiration
Pyruvate oxidation and the citric acid cycle: Cellular respirationOxidative phosphorylation: Cellular respirationVariations on cellular respiration: Cellular respiration

Unit 13: Photosynthesis

Intro to photosynthesis: PhotosynthesisThe light-dependent reactions: PhotosynthesisThe Calvin cycle: Photosynthesis
Photorespiration: C3, C4, and CAM plants: Photosynthesis

Unit 14: Cell signaling

How cells signal to each other: Cell signalingCommunication in single-celled organisms: Cell signalingCommunication in multicellular organisms: Cell signaling
Feedback: Cell signaling

Unit 15: Cell division

Introduction to cell division: Cell divisionThe cell cycle and mitosis: Cell divisionMeiosis: Cell division
Cell cycle regulation, cancer, and stem cells: Cell division

Unit 16: Classical and molecular genetics

Mendelian genetics: Classical and molecular geneticsVariations on Mendelian genetics: Classical and molecular geneticsChromosomal basis of genetics: Classical and molecular genetics
Sex linkage, chromosomal mutations, & non-nuclear inheritance: Classical and molecular geneticsMolecular basis of genetics: Classical and molecular genetics

Unit 17: DNA as the genetic material

Structure of DNA: DNA as the genetic materialDiscovery of DNA: DNA as the genetic materialDNA replication: DNA as the genetic material

Unit 18: Central dogma (DNA to RNA to protein)

Central dogma and the genetic code: Central dogma (DNA to RNA to protein)Transcription: Central dogma (DNA to RNA to protein)Translation: Central dogma (DNA to RNA to protein)

Unit 19: Gene regulation

Gene regulation in bacteria: Gene regulationGene regulation in eukaryotes: Gene regulation

Unit 20: Biotechnology

Intro to biotechnology: BiotechnologyDNA cloning: BiotechnologyDNA analysis methods: Biotechnology

Unit 21: More molecular biology

More about DNA and RNA: More molecular biologyMore about genetics: More molecular biologyMutations: More molecular biology
Metabolism: More molecular biologyMore about cell cycle: More molecular biologyMore about biotechnology: More molecular biology

Unit 22: Developmental biology

Development & differentiation: Developmental biologySignaling & transcription factors in development: Developmental biologyApoptosis: Developmental biology

Unit 23: Bacteria and archaea

Prokaryote structure: Bacteria and archaeaProkaryote metabolism and ecology: Bacteria and archaea

Unit 24: Viruses

Viruses: Viruses

Unit 25: Evolution and the tree of life

Evolution and natural selection: Evolution and the tree of lifePopulation genetics: Evolution and the tree of lifeSpeciation and evolutionary trees: Evolution and the tree of life

Unit 26: More about evolution and natural selection

Evidence of evolution: More about evolution and natural selectionArtificial selection: More about evolution and natural selectionMore about populations: More about evolution and natural selection
More evolution and natural selection practice: More about evolution and natural selection

Unit 27: History of life on Earth

Formation of Earth and early life: History of life on EarthThe diversification of life: History of life on EarthRadiometric dating: History of life on Earth

Unit 28: Ecology

Intro to ecology: EcologyIntro to population ecology: EcologyPopulation growth & regulation: EcologyIntro to community ecology: Ecology
Community structure & diversity: EcologyIntro to ecosystems: EcologyBiogeochemical cycles: EcologyBiogeography: Ecology

Unit 29: More about ecology

More about population ecology: More about ecologyLife histories: More about ecologyMore ecology practice: More about ecology

Unit 30: Biodiversity and conservation

Ecosystems & ecosystem services: Biodiversity and conservationGlobal distribution of biodiversity: Biodiversity and conservationThreats to biodiversity: Biodiversity and conservation
Protecting biodiversity: Biodiversity and conservationLevels of biodiversity: Biodiversity and conservation

Unit 31: Behavioral biology

Animal behavior: Behavioral biology

Unit 32: Principles of physiology

Body structure & homeostasis: Principles of physiologyMetabolism & thermoregulation: Principles of physiology

Unit 33: Human biology

Circulatory and pulmonary systems: Human biologyThe neuron and nervous system: Human biologyThe kidney and nephron: Human biology
Muscles: Human biologyImmunology: Human biology

Unit 34: Plant biology

Plant responses to light: Plant biology

Unit 35: AP free response worked examples

2015 Free response worked examples: AP free response worked examples

Unit 36: Crash Course: Biology and Ecology

Crash Course: Biology: Crash Course: Biology and EcologyCrash Course: Ecology: Crash Course: Biology and Ecology

Unit 37: Meet the biology professional

Meet the biology professional: Meet the biology professional
Community questions
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