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The Tian2 Study Library AP Edition · Tian2 Editorial Bureau
Volume I · MMXXVI AP Biology
Library› Catalogue› Sciences› AP Biology
⁂   Sciences · AP Exam

Biology Study Library.

AP Biology covers molecular biology, genetics, ecology, and evolution. One of the most concept-dense AP sciences — strong FRQ writers who can connect mechanism to outcome score 5s.

8 units 180 minutes 287,232 candidates
Total Time 180 minutes
MCQ 60 multiple-choice questions
FRQ 6 free-response questions
Score Scale 1-5 70.4% scored 3+
Mean Score 3.24 2025 national mean

About the exam

The AP Biology exam runs 3 hours. Section I (50%) has 60 multiple-choice questions in 90 minutes. Section II (50%) has 6 free-response questions in 90 minutes: 2 long FRQs (8–10 pts each) and 4 short FRQs (4 pts each). The exam is digital (Bluebook) for MCQ, paper for FRQ.

How to use this library

Each unit page below contains the full list of key topics, common exam errors to avoid, and a study guide section. Work through units in order, or jump directly to the unit with the highest exam weight — those are your highest-leverage study targets.

Exam strategy notes

  • Master the vocabulary — AP Biology FRQ rubrics are unforgiving of vague language. Write 'glycolysis occurs in the cytoplasm' not 'glycolysis happens in the cell.'
  • Draw and label diagrams when the prompt allows. A correctly labeled diagram of a signal transduction pathway or a Punnett square can earn points independent of your prose.
  • Learn to interpret graphs. Enzyme activity curves, population growth models, and Hardy-Weinberg allele frequency data all appear as stimulus material.
  • Connect units to each other. The Unit 3 (Cellular Energetics) concepts directly enable Unit 6 (Gene Expression) discussions of ATP-driven enzymes.
Curriculum

Study by unit.

1.
Chemistry of Life
Elements essential for carbon-based life · Properties of water: cohesion, adhesion, specific heat, polarity, hydrogen bonding · Biological macromolecules: carbohydrates, lipids, proteins, nucleic acids — structure and function · …
8–11% of exam
6 periods
Study unit ›
2.
Cell Structure and Function
Prokaryotic vs. eukaryotic cell structure and compartmentalization · Cell membrane: fluid mosaic model, phospholipid bilayer, membrane proteins · Passive transport: simple diffusion, facilitated diffusion, osmosis · …
10–13% of exam
12 periods
Study unit ›
3.
Cellular Energetics
Photosynthesis: light-dependent reactions — photosystems I and II, electron transport chain, ATP synthase, NADPH production · Photosynthesis: Calvin cycle (light-independent reactions) — carbon fixation, G3P production, RuBisCO · Cellular respiration: glycolysis — location (cytoplasm), inputs/outputs, net ATP yield · …
12–16% of exam
16 periods
Study unit ›
4.
Cell Communication and Cell Cycle
Signal transduction pathway stages: reception, transduction, response · Ligand-receptor specificity and signal amplification via second messengers · Types of cell signaling: endocrine (long-distance), paracrine, autocrine, direct contact (juxtacrine) · …
10–15% of exam
10 periods
Study unit ›
5.
Heredity
Meiosis I and II: stages, chromosome behavior, comparison with mitosis · Sources of genetic variation: crossing over (recombination), independent assortment, random fertilization · Mendelian genetics: law of segregation, law of independent assortment · …
8–11% of exam
10 periods
Study unit ›
6.
Gene Expression and Regulation
DNA structure: double helix, antiparallel strands, complementary base pairing · DNA replication: semiconservative model, leading and lagging strand synthesis, key enzymes (helicase, primase, DNA polymerase, ligase) · Transcription: RNA polymerase, promoter recognition, mRNA synthesis, termination · …
12–16% of exam
20 periods
Study unit ›
7.
Natural Selection
Evidence for evolution: fossil record, comparative anatomy (homologous, analogous, vestigial structures), molecular homology, biogeography · Mechanisms of natural selection: heritable variation, differential reproductive success, adaptation · Types of natural selection: directional, stabilizing, disruptive (diversifying) · …
13–20% of exam
22 periods
Study unit ›
8.
Ecology
Community ecology: species interactions — predation, interspecific competition, mutualism, commensalism, parasitism · Population ecology: exponential growth model (dN/dt = r_max N), logistic growth model (dN/dt = r_max N × (K−N)/K), carrying capacity (K) · Limiting factors: density-dependent vs. density-independent · …
10–15% of exam
20 periods
Study unit ›
Our worked solutions and practice questions are original instructional content created by Tian2 AP. They are aligned to the concepts and skills described in College Board’s Course and Exam Description and are not reproductions of, or affiliated with, College Board’s official materials.