The AP Biology curriculum is designed by the College Board to mirror a two-semester, introductory college-level biology course. The framework is structured around four Big Ideas (Evolution, Energetics, Information, and Interactions) and is broken down into eight units of study and six essential science practices.
The 8 Units of Study The curriculum is divided into eight units, each holding a specific weight on the AP Biology Exam:
Unit 1: Chemistry of Life (8%–11%) Structure of water and hydrogen bonding Elements of life and properties of biological macromolecules (carbohydrates, lipids, proteins, nucleic acids) Unit 2: Cell Structure and Function (10%–13%) Subcellular components and cell size constraints Plasma membrane structure, permeability, and transport mechanisms (passive vs. active) Tonicity, osmoregulation, and cellular compartmentalization Unit 3: Cellular Energetics (12%–16%) Enzyme structure, catalysis, and environmental impacts on function Cellular energy, photosynthesis pathways, and cellular respiration Unit 4: Cell Communication and Cell Cycle (10%–15%) Mechanisms of cell communication and signal transduction pathways Feedback loops and changes to signal pathways The cell cycle, mitosis, and regulation mechanisms Unit 5: Heredity (8%–11%) Meiosis and the generation of genetic diversity Mendelian and non-Mendelian genetics Environmental impacts on phenotype expression Unit 6: Gene Expression and Regulation (12%–16%) Structure and replication of DNA and RNA Transcription, RNA processing, and translation Mutations and basics of biotechnology (e.g., PCR, gel electrophoresis) Unit 7: Natural Selection (13%–20%) Evidence of evolution, common ancestry, and continuing evolution Population genetics and Hardy-Weinberg equilibrium calculations Phylogenetic trees, speciation, and the origins of life Unit 8: Ecology (10%–15%) Organism responses to environment and behavioral biology Energy flow through ecosystems, population ecology, and community ecology Biodiversity and ecosystem disruptions
The 6 Science Practices Students must not only learn the content but also master six inquiry-based skills tested throughout the course:
1. Concept Explanation: Explaining biological concepts, processes, and models in written format. 2. Visual Representations: Analyzing and creating biological diagrams, models, and flowcharts. 3. Questions and Methods: Identifying scientific questions, formulating hypotheses, and designing experiments. 4. Representing and Describing Data: Graphing data properly and describing patterns or trends. 5. Statistical Tests and Data Analysis: Using mathematical formulas and statistical tests (like Chi-Square, standard error, and mean) to analyze data. 6. Argumentation: Developing and supporting scientific claims with evidence and logical reasoning.
Exam Format Breakdown The final AP Biology Exam lasts 3 hours and is split evenly into two sections:
Section | Format | Timing | Weight
Section I | 60 Multiple-Choice Questions (individual and sets) | 90 minutes | 50% of score Section II | 6 Free-Response Questions (2 long, 4 short) | 90 minutes | 50% of score
Note: Graphing or scientific calculators are permitted for the entire duration of the test.
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