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APIntermediate
AP Biology
From cell structure to genetics, master the full AP Biology sequence with an AI layer that remembers how you learn.
📚 8 units🤖 AI-guided support✅ Practice questions included
📖Open Textbook→Course Units
2025–26 College Board CED1
Chemistry of Life8–11% of exam
1.1
Why Water Makes Life Possible
1.2
Carbon: The Backbone of Life
1.3
Carbohydrates — Energy and Structure
1.4
Lipids — Membranes, Energy, Signals
1.5
Proteins — Structure Dictates Function
1.6
Nucleic Acids — Storing and Transmitting Information
1.7
Enzymes: Lowering the Activation Energy Barrier
1.8
Cell Membrane Structure and Transport
2
Cell Structure and Function10–13% of exam
2.1
Prokaryotes vs. Eukaryotes — What the Difference Actually Means
2.2
Organelles: Form Follows Function
2.3
The Cytoskeleton — More Than a Scaffold
2.4
Cell Signaling — Receptors and Second Messengers
2.5
Membrane Transport — Moving Molecules In and Out
2.6
Water Potential and Osmosis in Plant vs. Animal Cells
2.7
Cell Communication: Direct Contact, Local, and Long-Distance
2.8
Feedback Loops and Homeostasis
3
Cellular Energetics12–16% of exam
3.1
Energy, Entropy, and Why Reactions Happen
3.2
ATP: The Currency of Cellular Work
3.3
Glycolysis — The Universal Starting Point
3.4
Pyruvate Oxidation and the Citric Acid Cycle
3.5
Electron Transport Chain and ATP Synthesis
3.6
Fermentation — Surviving Without Oxygen
3.7
Photosynthesis Overview — Light Reactions
3.8
Calvin Cycle — Fixing Carbon into Sugar
3.9
Cellular Respiration vs. Photosynthesis: The Energy Accounting
4
Cell Communication and Cell Cycle10–15% of exam
4.1
Signal Transduction: From Reception to Response
4.2
Cell Cycle: Phases, Checkpoints, and Control
4.3
Mitosis — Precise Chromosome Segregation
4.4
Meiosis — Generating Genetic Diversity
4.5
Cancer: When Cell Cycle Control Fails
4.6
Apoptosis — Programmed Cell Death as a Survival Strategy
4.7
Stem Cells and Cell Differentiation
4.8
Extracellular Matrix and Cell Junctions
5
Heredity8–11% of exam
5.1
Mendelian Genetics — The Rules of Inheritance
5.2
Beyond Mendelian Genetics — Dominance Patterns
5.3
Linked Genes and Recombination
5.4
Sex Determination and X-Linked Inheritance
5.5
Pedigree Analysis — Diagnosing Inheritance Patterns
5.6
Chromosomal Mutations — Nondisjunction and Aneuploidy
5.7
Epigenetics — Inheritance Without DNA Change
5.8
Quantitative Genetics — Polygenic Traits and Environment
6
Gene Expression and Regulation12–16% of exam
6.1
DNA Replication — Accuracy and the Machinery
6.2
Transcription — Reading DNA into RNA
6.3
Translation — Decoding mRNA into Protein
6.4
Mutations — Types, Consequences, and Repair
6.5
Gene Regulation in Prokaryotes — The Operon Model
6.6
Gene Regulation in Eukaryotes — Chromatin to Translation
6.7
Biotechnology — PCR, Gel Electrophoresis, Cloning
6.8
Gene Editing and CRISPR — Mechanism and Applications
7
Natural Selection13–20% of exam
7.1
Darwin's Mechanisms — Variation, Heritability, Selection
7.2
Hardy-Weinberg Equilibrium — The Null Model
7.3
Types of Natural Selection — Directional, Stabilizing, Disruptive
7.4
Genetic Drift and Gene Flow
7.5
Sexual Selection and Non-Random Mating
7.6
Speciation — How New Species Form
7.7
Phylogenetics — Reading the Tree of Life
7.8
Evidence for Evolution — Fossils, Biogeography, Molecular
8
Ecology10–15% of exam
8.1
Population Ecology — Growth Models and Limiting Factors
8.2
Community Ecology — Interactions and Stability
8.3
Ecosystem Ecology — Energy Flow and Trophic Levels
8.4
Biogeochemical Cycles — Carbon, Nitrogen, Phosphorus
8.5
Ecological Succession — Primary and Secondary
8.6
Biodiversity and Conservation
8.7
Human Impacts — Climate, Invasives, Extinction
8.8
Behavior — Proximate and Ultimate Causes