Course overview

AP Biology builds a connected model of life across scales. The course starts with chemistry that explains biological structure, moves through cells and energy flow, then develops heredity, gene regulation, evolution, and ecology using evidence-based reasoning.

Complete curriculum

Every unit and lesson

32 lessons total

01
Unit 1 · 4 lessons
Chemistry of Life
Explain how water, carbon chemistry, and biological macromolecules create the structural and chemical basis of living systems.
Why it matters
Cell behavior and organism traits depend on molecular interactions, so chemistry is the foundation for all later biology.
By the end, you will be able to
- Describe how polarity and hydrogen bonding in water support cohesion, adhesion, and thermal stability.
- Relate monomers and polymers to the structure and function of carbohydrates, lipids, proteins, and nucleic acids.
- Predict how changes in pH and environmental conditions can alter biological molecules and reactions.
1. 1.1
  Water and emergent properties
  Connect molecular polarity to biological effects like transport, temperature buffering, and surface behavior.
2. 1.2
  Carbon and functional groups
  Use functional groups to reason about molecular interactions and reactivity in cells.
3. 1.3
  Macromolecules and structure-function
  Compare macromolecule classes and explain how structure determines role.
4. 1.4
  Biological reactions and pH
  Interpret how acids, bases, and reaction conditions influence biomolecular systems.
Study unit 1 in detail
02
Unit 2 · 4 lessons
Cell Structure and Function
Analyze how cell components, membranes, and transport mechanisms support homeostasis and specialized cellular roles.
Why it matters
Understanding cell architecture explains how organisms maintain internal stability and carry out essential processes.
By the end, you will be able to
- Identify major organelles and connect their structures to core cellular functions.
- Explain membrane structure and selective permeability using phospholipids and embedded proteins.
- Distinguish passive and active transport and predict movement across concentration gradients.
1. 2.1
  Prokaryotic and eukaryotic cell organization
  Compare internal organization and infer functional consequences of compartmentalization.
2. 2.2
  Membrane structure and fluid mosaic model
  Use membrane composition to explain transport and signaling capacity.
3. 2.3
  Transport across membranes
  Model diffusion, osmosis, facilitated diffusion, and active transport in realistic contexts.
4. 2.4
  Cell size and surface area constraints
  Relate geometry to exchange rates and why cells remain small or specialized.
Study unit 2 in detail
03
Unit 3 · 4 lessons
Cellular Energetics
Trace energy transformation through photosynthesis and cellular respiration, including enzyme-driven pathways and ATP production.
Why it matters
Life depends on capturing, converting, and using energy to power growth, maintenance, and response.
By the end, you will be able to
- Describe how enzymes lower activation energy and how environmental factors affect enzyme activity.
- Connect light reactions and the Calvin cycle to the conversion of light energy into chemical energy.
- Compare glycolysis, Krebs cycle, and oxidative phosphorylation in terms of inputs, outputs, and ATP yield patterns.
1. 3.1
  Enzymes and metabolic pathways
  Use enzyme and substrate interactions to explain reaction rates and pathway regulation.
2. 3.2
  Photosynthesis mechanisms
  Map carbon and electron flow through major photosynthetic stages.
3. 3.3
  Cellular respiration stages
  Track matter and energy through aerobic respiration and ATP generation.
4. 3.4
  Energy coupling with ATP
  Explain how ATP hydrolysis drives endergonic cellular work.
Study unit 3 in detail
04
Unit 4 · 4 lessons
Cell Communication and Cell Cycle
Explain how cells receive signals, transduce information, and regulate growth, division, and differentiation through controlled checkpoints.
Why it matters
Multicellular life requires coordinated communication and controlled cell division to maintain function across tissues.
By the end, you will be able to
- Differentiate autocrine, paracrine, and endocrine signaling at the cellular level.
- Model signal transduction as reception, transduction, and response with amplification steps.
- Describe major phases of the cell cycle and how checkpoint failures affect tissue integrity.
1. 4.1
  Cell signaling modes
  Classify signaling pathways by source, distance, and target cell response.
2. 4.2
  Signal transduction pathways
  Trace receptor activation through intracellular cascades to changes in gene or protein activity.
3. 4.3
  Cell cycle and mitosis
  Explain events in interphase and mitosis with emphasis on accurate chromosome segregation.
4. 4.4
  Cell cycle regulation
  Relate checkpoint control proteins to division timing and error prevention.
Study unit 4 in detail
05
Unit 5 · 4 lessons
Heredity
Apply Mendelian and chromosomal models to explain inheritance patterns, meiosis, and sources of genetic variation.
Why it matters
Inheritance principles explain how traits persist or change across generations in families and populations.
By the end, you will be able to
- Use meiosis stages to explain reduction of chromosome number and independent assortment.
- Solve monohybrid and dihybrid inheritance problems using probabilistic reasoning.
- Interpret deviations from simple Mendelian ratios, including linkage and non-Mendelian patterns.
1. 5.1
  Meiosis and variation
  Connect crossing over and independent assortment to new allele combinations.
2. 5.2
  Mendelian inheritance models
  Use Punnett squares and probability rules to predict genotype and phenotype outcomes.
3. 5.3
  Chromosomal basis of inheritance
  Link gene location on chromosomes to segregation patterns.
4. 5.4
  Beyond simple dominance
  Evaluate codominance, incomplete dominance, and linkage from observed data.
Study unit 5 in detail
06
Unit 6 · 4 lessons
Gene Expression and Regulation
Follow information flow from DNA to RNA to protein and explain how cells regulate expression across different contexts.
Why it matters
Cell identity and adaptive response depend on when, where, and how strongly genes are expressed.
By the end, you will be able to
- Describe replication, transcription, and translation with key enzymes and molecular roles.
- Explain how mutations can alter gene products or regulatory control.
- Compare regulatory mechanisms in prokaryotes and eukaryotes, including epigenetic effects.
1. 6.1
  DNA replication and fidelity
  Explain semiconservative replication and mechanisms that reduce copying errors.
2. 6.2
  Transcription and translation
  Map codons, mRNA processing, and ribosome function to protein synthesis.
3. 6.3
  Gene regulation in cells
  Interpret how promoters, transcription factors, and chromatin state affect expression levels.
4. 6.4
  Mutations and expression outcomes
  Predict how sequence or regulatory changes can impact phenotype.
Study unit 6 in detail
07
Unit 7 · 4 lessons
Natural Selection
Use population-level evidence to explain evolution through variation, differential reproductive success, and changing allele frequencies.
Why it matters
Evolution by natural selection is a central framework that unifies biological diversity and adaptation.
By the end, you will be able to
- Distinguish evolution as population change from acclimation in an individual organism.
- Explain how mutation, gene flow, genetic drift, and selection can shift allele frequencies.
- Evaluate evolutionary claims using data from fossils, comparative anatomy, molecular evidence, and population studies.
1. 7.1
  Population genetics foundations
  Define allele frequency and conditions for Hardy-Weinberg equilibrium.
2. 7.2
  Mechanisms of evolutionary change
  Compare directional effects of selection with stochastic effects of drift.
3. 7.3
  Evidence for common ancestry
  Integrate anatomical, molecular, and fossil evidence into coherent evolutionary explanations.
4. 7.4
  Speciation and macroevolution patterns
  Connect reproductive isolation and divergence to new species formation.
Study unit 7 in detail
08
Unit 8 · 4 lessons
Ecology
Analyze interactions among organisms and environments, including energy transfer, nutrient cycling, population dynamics, and ecosystem stability.
Why it matters
Ecology explains how biological systems persist, recover, or shift when conditions and interactions change.
By the end, you will be able to
- Model energy flow through trophic levels and explain limits on transfer efficiency.
- Relate biogeochemical cycles to ecosystem productivity and long-term stability.
- Use population growth models and interaction types to predict community-level effects.
1. 8.1
  Energy flow and trophic structure
  Quantify transfer between producers, consumers, and decomposers using ecological pyramids.
2. 8.2
  Biogeochemical cycles
  Trace carbon, nitrogen, and water movement across biotic and abiotic reservoirs.
3. 8.3
  Population ecology
  Compare exponential and logistic growth and interpret carrying capacity in context.
4. 8.4
  Community interactions and resilience
  Evaluate competition, predation, symbiosis, and disturbance responses.
Study unit 8 in detail

AP Biology

Course overview

Every unit and lesson

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