AP-BIO
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AP® Biology
AP Biology delivers an AP-level overview of chemistry of life, cell structure, energetics, communication, and heredity, preparing students to master core biological concepts and analytical skills essential for college science.
180
Minutes
66
Questions
3/5
Passing Score
$98
Exam Cost
Who Should Take This
High‑school juniors and seniors aiming for college credit, as well as early‑college students seeking a rigorous foundation, should take AP Biology. Ideal learners have a solid grasp of high‑school science, are comfortable with detailed terminology, and want to develop problem‑solving and data‑analysis abilities for future biology or health‑related majors.
What's Covered
1
All eight units of the AP Biology course framework (College Board, effective 2020-present): Unit 1 Chemistry of Life
2
, Unit 2 Cell Structure and Function
3
, Unit 3 Cellular Energetics
4
, Unit 4 Cell Communication and Cell Cycle
5
, Unit 5 Heredity
6
, Unit 6 Gene Expression and Regulation
7
, Unit 7 Natural Selection
8
, Unit 8 Ecology
What's Included in AccelaStudy® AI
Adaptive Knowledge Graph
Practice Questions
Lesson Modules
Console Simulator Labs
Exam Tips & Strategy
20 Activity Formats
Course Outline
78 learning goals
1
Unit 1: Chemistry of Life
3 topics
Water and Biological Macromolecules
- Identify the unique properties of water (cohesion, adhesion, high specific heat, high heat of vaporization, solvent capacity, lower density of ice) and explain how these properties support living systems.
- Describe the structure and function of the four major classes of biological macromolecules—carbohydrates, lipids, proteins, and nucleic acids—including their monomers, polymer linkages, and primary biological roles.
- Explain how the sequence of amino acids in a protein determines its three-dimensional structure, and how denaturation disrupts function by altering protein shape without breaking the primary sequence.
Enzymes and Reaction Kinetics
- Explain how enzymes function as biological catalysts by lowering activation energy and describe the induced-fit model of enzyme-substrate interaction at the active site.
- Analyze how environmental factors (temperature, pH, substrate concentration, cofactors, competitive and non-competitive inhibitors) affect enzyme activity rates and explain the physiological significance of each effect.
- Evaluate how feedback inhibition and allosteric regulation of enzyme activity allow cells to control metabolic pathway flux in response to changing cellular conditions.
Nucleic Acid Structure
- Identify the structural components of DNA and RNA nucleotides, explain the antiparallel orientation and complementary base-pairing rules, and distinguish between the double helix of DNA and the single-stranded nature of most RNA molecules.
2
Unit 2: Cell Structure and Function
3 topics
Cell Organization and Organelles
- Identify the structural and functional differences between prokaryotic and eukaryotic cells, naming the organelles and structures unique to each cell type and their functional significance.
- Explain how the endosymbiotic theory accounts for the evolutionary origin of mitochondria and chloroplasts, citing the structural and genomic evidence that supports this hypothesis.
- Explain the structure and function of the endomembrane system by tracing the path of a secretory protein through the rough ER, Golgi apparatus, and vesicular transport to the plasma membrane or extracellular space.
Cell Membrane Structure and Transport
- Describe the fluid mosaic model of the plasma membrane, identifying the roles of phospholipids, cholesterol, integral proteins, peripheral proteins, and glycoproteins in membrane structure and function.
- Explain the mechanisms of passive transport (simple diffusion, facilitated diffusion, osmosis) and active transport (primary and secondary active transport), distinguishing how each mechanism relates to the electrochemical gradient.
- Analyze the effects of hypertonic, hypotonic, and isotonic solutions on animal and plant cells, predicting changes in cell volume, turgor pressure, and water potential in each condition.
- Explain how membrane selectivity enables cells to maintain homeostasis by regulating the import of nutrients, export of waste products, and maintenance of ion gradients essential for cellular function.
Surface Area-to-Volume and Cell Size
- Analyze how the surface area-to-volume ratio constrains cell size and shape, and explain how adaptations such as microvilli, folded membranes, and compartmentalization allow cells to overcome this physical limitation.
- Evaluate how multicellularity and cell specialization allow organisms to overcome the limitations imposed on individual cells by surface area-to-volume constraints and diffusion distances.
3
Unit 3: Cellular Energetics
3 topics
Photosynthesis
- Describe the overall equation for photosynthesis, identify the reactants and products of the light-dependent and light-independent (Calvin cycle) reactions, and locate where each set of reactions occurs within the chloroplast.
- Explain how the light-dependent reactions convert solar energy into chemical energy (ATP and NADPH) through the activity of photosystems I and II, the electron transport chain, and ATP synthase via the chemiosmotic mechanism.
- Explain how the Calvin cycle uses ATP and NADPH to fix carbon dioxide into G3P through the activities of RuBisCO, and describe the three phases: carbon fixation, reduction, and regeneration of RuBP.
- Analyze how environmental factors (light intensity, CO2 concentration, temperature, water availability) affect the rate of photosynthesis, and explain the concept of limiting factors using experimental data.
Cellular Respiration
- Describe the overall equation for aerobic cellular respiration and identify the reactants, products, and net ATP yield from glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation.
- Explain the chemiosmotic mechanism of ATP synthesis in the mitochondria, tracing how the electron transport chain establishes a proton gradient across the inner mitochondrial membrane that drives ATP synthase.
- Explain the mechanisms and products of anaerobic fermentation (lactic acid and alcoholic fermentation), why fermentation regenerates NAD+ to sustain glycolysis, and the difference in ATP yield between aerobic and anaerobic pathways.
- Analyze how organisms regulate cellular respiration in response to cellular energy charge (ATP:ADP ratio) and substrate availability, including the role of key allosteric enzymes such as phosphofructokinase in glycolytic control.
Energy Transformation Integration
- Evaluate the structural and functional parallels between chloroplasts and mitochondria in ATP synthesis, explaining how both organelles exploit membrane-embedded ATP synthases and proton gradients derived from electron transport chains.
- Analyze how disruptions to cellular respiration or photosynthesis (e.g., inhibitors, mutations in electron transport chain components) affect organismal energy balance and explain the downstream physiological consequences.
- Explain how the free energy released from oxidation-reduction reactions during cellular respiration is coupled to the endergonic synthesis of ATP, illustrating the thermodynamic principles of energy coupling in biological systems.
4
Unit 4: Cell Communication and Cell Cycle
3 topics
Cell Signaling and Signal Transduction
- Identify the three stages of cell signaling (reception, transduction, response) and describe the three main types of cell signaling (autocrine, paracrine, endocrine) based on the distance over which the signal acts.
- Explain signal transduction pathways involving G-protein coupled receptors, receptor tyrosine kinases, and ligand-gated ion channels, tracing how each receptor type converts an extracellular signal into an intracellular response.
- Explain how second messengers (cAMP, IP3, Ca2+) amplify signals within cells during signal transduction, and describe the role of protein kinase cascades in signal amplification and specificity.
- Analyze how defects in cell signaling pathways (e.g., constitutively active Ras mutations, loss-of-function receptor defects) lead to diseases such as cancer or hormone insensitivity, connecting molecular mechanism to phenotypic outcome.
The Cell Cycle and Mitosis
- Describe the phases of the eukaryotic cell cycle (G1, S, G2, M), identifying what occurs during each phase of interphase and what major events characterize each stage of mitosis (prophase, metaphase, anaphase, telophase).
- Explain how cyclin-CDK complexes, checkpoints (G1, G2, spindle assembly), and regulatory proteins (p53, Rb) control progression through the cell cycle and maintain genomic integrity.
- Analyze how mutations in proto-oncogenes and tumor suppressor genes disrupt normal cell cycle regulation, explaining the multi-hit hypothesis for carcinogenesis and how different categories of mutations promote uncontrolled cell division.
Meiosis and Genetic Variation
- Compare meiosis and mitosis, distinguishing the number of divisions, crossing over in prophase I, independent assortment at metaphase I, and the ploidy of the resulting cells in each process.
- Evaluate how crossing over, independent assortment, and random fertilization each contribute independently to the genetic variation among offspring produced by sexual reproduction.
5
Unit 5: Heredity
3 topics
Mendelian Genetics
- Identify Mendel's laws of segregation and independent assortment, and use Punnett squares and probability rules to predict genotypic and phenotypic ratios for monohybrid and dihybrid crosses.
- Explain the patterns of non-Mendelian inheritance including incomplete dominance, codominance, multiple alleles, pleiotropy, and polygenic inheritance, providing examples of each and distinguishing how each deviates from Mendel's laws.
- Analyze inheritance patterns for X-linked traits, predicting offspring phenotypes and genotypes in sex-linked crosses and explaining why X-linked recessive traits are expressed more frequently in males than females.
Chromosomal Basis of Inheritance
- Explain how genetic linkage and recombination frequency are used to construct chromosome maps, describing how the frequency of crossing over between two loci is proportional to the distance between them in centimorgans.
- Describe chromosomal mutations (deletions, duplications, inversions, translocations, aneuploidy) and explain how errors in meiosis such as nondisjunction produce chromosomal abnormalities including trisomy and monosomy.
- Apply chi-square statistical analysis to genetics data to determine whether observed ratios of offspring phenotypes deviate significantly from expected Mendelian ratios, and interpret what a significant chi-square result implies about the hypothesis.
Environmental Influences on Phenotype
- Evaluate how phenotypic plasticity allows the same genotype to produce different phenotypes in different environments, and assess the relative contributions of genotype, environment, and their interaction to quantitative trait variation.
6
Unit 6: Gene Expression and Regulation
4 topics
DNA Replication
- Explain the mechanism of semi-conservative DNA replication, identifying the roles of helicase, primase, DNA polymerase III, DNA polymerase I, and ligase in producing leading and lagging strand synthesis.
- Explain how DNA proofreading and repair mechanisms (mismatch repair, nucleotide excision repair, base excision repair) reduce the mutation rate and maintain genome fidelity during and after replication.
Transcription and Translation
- Describe the process of transcription in prokaryotes and eukaryotes, identifying the roles of RNA polymerase, promoters, and transcription factors, and explaining the post-transcriptional modifications made to eukaryotic pre-mRNA (5' cap, poly-A tail, splicing).
- Explain the process of translation, describing how ribosomes, mRNA codons, tRNA anticodons, and aminoacyl-tRNA synthetases collaborate to synthesize a polypeptide chain from the start codon to the stop codon.
- Analyze how point mutations (missense, nonsense, silent, frameshift) alter codon sequences and affect protein structure and function, predicting the consequence of each mutation type on the polypeptide product.
Gene Regulation
- Explain how prokaryotic gene expression is regulated by the lac operon and trp operon models, distinguishing inducible from repressible operons and describing how negative and positive regulation interact to control transcription.
- Explain the mechanisms of eukaryotic gene regulation including histone modification (methylation, acetylation), DNA methylation, transcription factor binding to enhancers and silencers, and alternative splicing of pre-mRNA.
- Explain how non-coding RNAs including miRNA and siRNA regulate gene expression post-transcriptionally through mRNA degradation and translational repression, and describe their significance in development and disease.
- Evaluate how epigenetic modifications that alter chromatin structure can be heritable across cell divisions without changing the DNA sequence, and analyze the role of epigenetics in cell differentiation and organismal development.
Biotechnology
- Describe the principles of PCR, gel electrophoresis, and CRISPR-Cas9 gene editing, explaining how each technique exploits fundamental properties of DNA replication, size-based separation, or RNA-guided DNA cleavage.
- Analyze how biotechnology applications including recombinant DNA technology, transgenic organisms, and CRISPR-based therapies raise ethical considerations regarding safety, equity, and unintended ecological consequences.
7
Unit 7: Natural Selection
5 topics
Evidence for Evolution
- Identify the multiple lines of evidence for evolution including the fossil record, biogeography, comparative anatomy (homologous and analogous structures, vestigial structures), comparative embryology, and molecular evidence from DNA and protein sequence similarity.
- Explain how phylogenetic trees and cladograms are constructed using shared derived characters (synapomorphies), and interpret branching diagrams to identify common ancestors, evolutionary relationships, and relative divergence times.
Mechanisms of Evolution
- Describe the mechanisms of evolutionary change including natural selection, genetic drift, gene flow, mutation, and sexual selection, and identify conditions under which each mechanism has the greatest effect on allele frequencies.
- Explain the Hardy-Weinberg principle as a null model for population genetics, state the five conditions required for Hardy-Weinberg equilibrium, and calculate allele and genotype frequencies using the Hardy-Weinberg equations p + q = 1 and p2 + 2pq + q2 = 1.
- Analyze deviations from Hardy-Weinberg equilibrium in population data to identify which evolutionary force (selection, drift, gene flow, non-random mating) is likely driving allele frequency change and justify the inference with quantitative evidence.
- Compare directional, stabilizing, and disruptive selection as modes of natural selection, explaining how each mode alters the distribution of a phenotypic trait in a population over time.
Speciation and Macroevolution
- Explain the biological species concept and describe the mechanisms of allopatric and sympatric speciation, identifying the prezygotic and postzygotic reproductive isolating barriers that maintain species boundaries.
- Evaluate the relative contributions of gradualism and punctuated equilibrium to macroevolutionary patterns observed in the fossil record, and analyze how mass extinctions and adaptive radiations reshape the distribution of biological diversity over geological time.
Origin of Life and Molecular Evolution
- Explain the chemical evolution hypothesis for the origin of life, including the significance of Miller-Urey experiments, the RNA world hypothesis, and protocell formation in proposed scenarios for the emergence of self-replicating molecules.
- Analyze molecular clock data and sequence divergence estimates to infer evolutionary relationships and divergence times among taxa, evaluating the assumptions and limitations of the molecular clock model.
- Evaluate how the universal genetic code, conserved molecular mechanisms (e.g., ATP synthesis, DNA replication), and shared metabolic pathways provide molecular evidence for the common ancestry of all living organisms.
Coevolution and Adaptation
- Analyze examples of coevolution (host-pathogen arms races, mutualistic pollinator-plant relationships, predator-prey interactions) and explain how reciprocal selective pressures drive evolutionary change in both interacting lineages.
8
Unit 8: Ecology
4 topics
Population Ecology
- Describe the properties of populations (size, density, distribution patterns, age structure, sex ratio) and explain how birth rates, death rates, immigration, and emigration determine changes in population size over time.
- Compare exponential and logistic population growth models, explaining how carrying capacity (K) and per capita growth rate (r) interact to produce the S-shaped logistic growth curve and identifying conditions under which each model applies.
- Analyze how density-dependent factors (predation, competition, disease, resource depletion) and density-independent factors (temperature extremes, natural disasters) regulate population size and contribute to population cycles.
- Explain r-selected and K-selected life history strategies, comparing the reproductive output, offspring survival rates, and population growth characteristics of organisms adapted to unstable versus stable environments.
Community Ecology
- Describe the types of species interactions (predation, competition, mutualism, commensalism, parasitism) and explain how each interaction affects the population sizes and fitness of the interacting species.
- Explain the competitive exclusion principle and the concept of the ecological niche, describing how resource partitioning and character displacement allow ecologically similar species to coexist within a community.
- Explain primary and secondary ecological succession by identifying pioneer and climax communities, the role of facilitation and inhibition in succession, and how keystone species and disturbance regimes affect long-term community structure.
Ecosystem Ecology and Energy Flow
- Explain the flow of energy through ecosystems via food chains and food webs, including the 10% rule for trophic energy transfer efficiency, and calculate the energy available at each trophic level given primary productivity data.
- Describe the carbon, nitrogen, and phosphorus biogeochemical cycles, identifying the key biological and abiotic processes that move each element through its respective reservoirs and explaining the ecological consequences of cycle disruption.
- Analyze how human activities (fossil fuel combustion, deforestation, agriculture, industrial emissions) alter biogeochemical cycles and lead to environmental consequences such as climate change, eutrophication, acid rain, and ozone depletion.
Biodiversity and Conservation
- Evaluate the relationship between species diversity (species richness and evenness), ecosystem stability, and ecosystem services, analyzing how biodiversity loss reduces ecosystem resilience to disturbance.
- Analyze the primary drivers of biodiversity loss (habitat destruction and fragmentation, invasive species, overexploitation, pollution, climate change) and evaluate the effectiveness of conservation strategies including protected areas, habitat corridors, and species reintroduction programs.
Scope
Included Topics
- All eight units of the AP Biology course framework (College Board, effective 2020-present): Unit 1 Chemistry of Life (8-11%), Unit 2 Cell Structure and Function (10-13%), Unit 3 Cellular Energetics (12-16%), Unit 4 Cell Communication and Cell Cycle (10-15%), Unit 5 Heredity (8-11%), Unit 6 Gene Expression and Regulation (12-16%), Unit 7 Natural Selection (13-20%), Unit 8 Ecology (10-15%).
- Core biological chemistry: water properties, macromolecule structure and function (carbohydrates, lipids, proteins, nucleic acids), enzyme kinetics, and how molecular structure determines biological function.
- Cell biology: prokaryotic and eukaryotic cell structure, membrane structure and transport mechanisms (passive and active), organelle function, and the endomembrane system.
- Energy transformations: photosynthesis (light-dependent and light-independent reactions), cellular respiration (glycolysis, pyruvate oxidation, Krebs cycle, oxidative phosphorylation), and fermentation pathways.
- Cell communication and the cell cycle: signal transduction pathways, second messenger systems, mitosis, meiosis, and regulation of the cell cycle including cancer mechanisms.
- Heredity: Mendelian genetics, non-Mendelian inheritance patterns, chromosomal inheritance, the chromosomal basis of sex-linked traits, and quantitative analysis of inheritance using chi-square statistics.
- Gene expression and regulation: DNA replication, transcription, translation, gene regulation in prokaryotes and eukaryotes, mutations, biotechnology techniques (PCR, gel electrophoresis, CRISPR), and the role of non-coding RNAs.
- Evolution and natural selection: Hardy-Weinberg equilibrium, mechanisms of evolutionary change, phylogenetics, speciation, and evidence for evolution from multiple lines of inquiry.
- Ecology: population dynamics, community ecology, ecosystem energy flow and nutrient cycling, and the impact of human activity on biodiversity and ecosystem stability.
- Exam-aligned skills including data analysis, experimental design, mathematical modeling, and scientific argumentation as tested in AP Biology free-response and multiple-choice questions.
Not Covered
- Biochemical reaction mechanisms and organic chemistry beyond the AP framework, including detailed enzyme catalytic mechanisms, metabolic intermediary chemistry, and thermodynamic derivations.
- Clinical pathology, pharmacology, and medical applications beyond what is required for AP-level biological understanding.
- Advanced genomics, proteomics, and systems biology approaches beyond the introductory scope of the AP Biology framework.
- Organismal anatomy and physiology content covered primarily by AP Environmental Science or introductory college anatomy courses.
Official Exam Page
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