AP Biology

743 indexed practice questions across 8 units. Open a unit for a summary and question list with links to full explanations.

easy 335medium 329hard 79

Units

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

AP Biology FAQ

›How many AP Biology practice questions does Apentix have?

743 questions across 8 units: every question includes a full explanation and is tagged by difficulty (easy, medium, hard).

›Are these questions like the real AP Biology exam?

Yes, questions follow College Board's unit weighting and format for AP Biology, including stimulus-based and standalone multiple choice with AP-style distractors.

›Is it free?

Yes. Browsing questions, unit guides, and cheatsheets is free; a free account adds progress tracking, assignments, and classroom games.