AP Biology
884 indexed practice questions across 8 units. Open a unit for a summary and question list with links to full explanations.
Units
- Unit 1: Chemistry of Life113 questions
- Unit 2: Cell Structure and Function116 questions
- Unit 3: Cellular Energetics113 questions
- Unit 4: Cell Communication and Cell Cycle108 questions
- Unit 5: Heredity108 questions
- Unit 6: Gene Expression and Regulation108 questions
- Unit 7: Natural Selection108 questions
- Unit 8: Ecology110 questions
AP Biology Universal Cheatsheet
Key Vocabulary
Amphipathic — Has both hydrophilic and hydrophobic regions
Endosymbiosis — Mitochondria/chloroplasts evolved from engulfed prokaryotes
Chemiosmosis — H⁺ gradient drives ATP synthase
Osmoregulation — Controlling water/solute balance
Plasmolysis — Cell membrane detaches from wall (hypertonic)
Epistasis — One gene masks expression of another
Hardy-Weinberg — p² + 2pq + q² = 1; no evolution if assumptions met
Bottleneck Effect — Population drastically reduced, genetic drift
K-selection — Few offspring, high parental care (stable env)
r-selection — Many offspring, low care (unstable env)
Transcription — DNA → mRNA (RNA polymerase, promoter, terminator)
Translation — mRNA → protein (ribosome, tRNA, codons)
Operon — Cluster of genes regulated together (e.g., lac operon)
PCR — Polymerase Chain Reaction: amplify DNA (Taq polymerase)
Chi-square (χ²) — Tests if observed data fits expected ratios
Gibberellins — Plant hormone promoting stem elongation
Critical Concepts
- • Surface Area : Volume — As cells grow, SA/V decreases, limiting exchange
- • Water Potential (Ψ) = Ψₛ (solute) + Ψₚ (pressure); water moves high → low Ψ
- • Cellular Respiration: Glycolysis → Pyruvate Oxidation → Krebs → ETC → ~36-38 ATP
- • Photosynthesis: Light Rxns (thylakoid) + Calvin Cycle (stroma) → G3P
- • Cell Cycle Checkpoints: G1/S (commitment), G2/M (DNA integrity), M (spindle)
- • Meiosis vs Mitosis: Meiosis = 2 divisions, 4 haploid, crossing over; Mitosis = 1 division, 2 diploid
- • Linked Genes — Don't assort independently; recombination frequency = map distance
- • Ecological Efficiency — ~10% energy transfers between trophic levels
Lab Exam Tips
- • Always identify the independent variable (manipulated) and dependent variable (measured)
- • Use chi-square analysis when comparing observed vs expected outcomes
- • Water potential problems: remember Ψ = 0 for pure open water at atmospheric pressure
- • FRQ: claim + evidence + reasoning — always cite specific data from the question