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100+ Free AP Biology Practice Questions

Pass your AP Biology (Advanced Placement Biology) exam on the first try — instant access, no signup required.

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Key Facts: AP Biology Exam

60

multiple-choice questions in Section I (1 hr 30 min, 50% of score)

College Board

6

free-response questions in Section II (two long, four short)

College Board

8

units of content, from Chemistry of Life to Ecology

College Board CED

13-20%

exam weight of Unit 7 Natural Selection, the largest

College Board CED

1-5

score scale, with 3 or higher generally earning college credit

College Board

3 hours

total exam time, split evenly between the two sections

College Board

The AP Biology exam is 3 hours long and split evenly between two sections. Section I is 60 multiple-choice questions in 1 hour 30 minutes (50% of the score), and Section II is 6 free-response questions (two long and four short) in 1 hour 30 minutes (50% of the score). Content is drawn from 8 units, with Natural Selection (13-20%) the most heavily weighted and Chemistry of Life and Heredity (8-11% each) the least. A four-function, scientific, or graphing calculator is permitted on both sections, and exams are scored 1-5, with a 3 or higher generally earning college credit (source: College Board, apstudents.collegeboard.org).

Sample AP Biology Practice Questions

Try these sample questions to test your AP Biology exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which property of water is most directly responsible for its ability to moderate temperature in living organisms and large bodies of water?
A.Its low specific heat
B.Its inability to form hydrogen bonds
C.Its nonpolar covalent bonds
D.Its high specific heat
Explanation: Water has a high specific heat because hydrogen bonds must absorb or release substantial energy before water molecules change temperature. This allows water and water-rich organisms to resist large temperature swings, helping maintain homeostasis.
2Two solutions are separated by a membrane permeable only to water. Side A holds a high solute concentration and side B a low solute concentration. In which direction will water move by osmosis?
A.From side A to side B
B.From side B to side A
C.No net movement occurs
D.Equally in both directions until solute moves
Explanation: Osmosis moves water from a region of lower solute concentration (higher water potential) to a region of higher solute concentration (lower water potential). Water therefore moves from side B to side A until water potential equalizes.
3Which monomers join through dehydration synthesis to form the polymer that stores genetic information?
A.Amino acids
B.Monosaccharides
C.Fatty acids
D.Nucleotides
Explanation: Nucleic acids such as DNA and RNA are polymers built from nucleotide monomers, each consisting of a sugar, a phosphate, and a nitrogenous base. Dehydration synthesis links nucleotides via phosphodiester bonds to store genetic information.
4The three-dimensional shape of a protein, including its biological activity, depends most directly on which level of structure being maintained?
A.The primary sequence alone, with shape irrelevant
B.The tertiary structure determined by interactions among R groups
C.Only the peptide bonds in the backbone
D.The number of phosphate groups attached
Explanation: A protein's tertiary structure, its overall 3D folding, arises from interactions among amino acid R groups, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges. This folding determines the protein's function; denaturation disrupts it.
5Why are carbon atoms especially well suited to form the diverse molecules that make up living organisms?
A.Carbon can form only single bonds, keeping molecules simple
B.Carbon is the most electronegative element
C.Carbon has four valence electrons and forms four covalent bonds, allowing branched, ringed, and chained structures
D.Carbon readily forms ionic bonds with water
Explanation: Carbon has four valence electrons and can form four stable covalent bonds with carbon and other atoms. This versatility allows long chains, branches, and rings, producing the enormous diversity of organic molecules found in life.
6Which functional group, when added to a molecule, generally makes that region more acidic by releasing a hydrogen ion?
A.Hydroxyl group
B.Amino group
C.Carboxyl group
D.Methyl group
Explanation: A carboxyl group can ionize by donating a hydrogen ion, releasing H+ and becoming negatively charged. This behavior makes carboxyl-containing molecules, such as fatty acids and amino acids, acidic.
7Saturated and unsaturated fatty acids differ primarily in that unsaturated fatty acids contain
A.One or more carbon-carbon double bonds creating kinks in the tail
B.More phosphate groups
C.No carboxyl group
D.Nitrogen in their hydrocarbon tails
Explanation: Unsaturated fatty acids have one or more carbon-carbon double bonds, which introduce kinks in the hydrocarbon tail. These kinks prevent tight packing, so unsaturated fats tend to be liquid at room temperature, unlike saturated fats.
8Which pair correctly matches a biological macromolecule with one of its primary functions?
A.Cellulose - long-term energy storage in animals
B.Glucose - storing hereditary information
C.DNA - catalyzing most metabolic reactions
D.Phospholipids - forming the bilayer of cell membranes
Explanation: Phospholipids have hydrophilic heads and hydrophobic tails, causing them to self-assemble into a bilayer that forms the structural basis of cell membranes. This arrangement controls what enters and leaves the cell.
9A polysaccharide is hydrolyzed in a test tube. Which products and conditions are most consistent with this reaction?
A.Monosaccharides are released and a water molecule is consumed per bond broken
B.Amino acids are released and water is produced
C.Nucleotides are released and ATP is consumed
D.Fatty acids are released and oxygen is produced
Explanation: Hydrolysis breaks the glycosidic bonds of a polysaccharide by adding water, releasing monosaccharide subunits. Each bond broken consumes one water molecule, the reverse of dehydration synthesis.
10Which structure is found in a typical plant cell but NOT in a typical animal cell?
A.Mitochondrion
B.Nucleus
C.Ribosome
D.Cell wall made of cellulose
Explanation: Plant cells have a rigid cell wall composed primarily of cellulose that surrounds the plasma membrane, providing structural support. Animal cells lack a cell wall, relying on the cytoskeleton and extracellular matrix instead.

About the AP Biology Exam

AP Biology is a college-level introductory biology course and exam administered by the College Board. The course is organized into 8 units spanning the chemistry of life, cell structure and function, cellular energetics, cell communication and the cell cycle, heredity, gene expression and regulation, natural selection, and ecology. The exam is 3 hours long: Section I has 60 multiple-choice questions (1 hr 30 min, 50% of the score) and Section II has 6 free-response questions (1 hr 30 min, 50% of the score). It is scored on a 1-5 scale.

Questions

60 scored questions

Time Limit

3 hours (1 hr 30 min multiple-choice + 1 hr 30 min free-response)

Passing Score

Scored 1-5; a 3+ typically earns college credit

Exam Fee

About $99 per exam in the US (2025-26) (College Board)

AP Biology Exam Content Outline

8-11%

Unit 1: Chemistry of Life

Water properties, macromolecules, and the elements and functional groups of living systems.

10-13%

Unit 2: Cell Structure and Function

Organelles, membrane structure and transport, and surface-area-to-volume relationships.

12-16%

Unit 3: Cellular Energetics

Enzymes, photosynthesis, cellular respiration, and energy capture and release.

10-15%

Unit 4: Cell Communication and Cell Cycle

Cell signaling, signal transduction, feedback, and regulation of the cell cycle and mitosis.

8-11%

Unit 5: Heredity

Meiosis, Mendelian and non-Mendelian inheritance, and chromosomal inheritance.

12-16%

Unit 6: Gene Expression and Regulation

DNA/RNA structure, replication, transcription, translation, gene regulation, and biotechnology.

13-20%

Unit 7: Natural Selection

Natural selection, evidence for evolution, Hardy-Weinberg, speciation, and phylogeny.

10-15%

Unit 8: Ecology

Animal behavior, energy flow, population and community ecology, and ecosystem dynamics.

How to Pass the AP Biology Exam

What You Need to Know

  • Passing score: Scored 1-5; a 3+ typically earns college credit
  • Exam length: 60 questions
  • Time limit: 3 hours (1 hr 30 min multiple-choice + 1 hr 30 min free-response)
  • Exam fee: About $99 per exam in the US (2025-26)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

AP Biology Study Tips from Top Performers

1Prioritize Unit 7 (Natural Selection) and Units 3 and 6 (Cellular Energetics, Gene Expression) since they carry the most multiple-choice weight.
2Practice data analysis and graph interpretation; many questions present a data set, diagram, or experiment and ask you to draw conclusions.
3Master the experimental-design skill: identify independent and dependent variables, controls, and how to support a claim with evidence.
4Memorize key quantitative tools such as the Hardy-Weinberg equations and chi-square test, which appear on the official AP Biology equations and formulas sheet.
5Use the official AP Biology equations sheet during practice so you are fluent with it on test day.

Frequently Asked Questions

How many questions are on the AP Biology exam and how long is it?

The AP Biology exam is 3 hours long. Section I has 60 multiple-choice questions in 1 hour 30 minutes (50% of the score), and Section II has 6 free-response questions in 1 hour 30 minutes (50% of the score).

What units does AP Biology cover?

AP Biology has 8 units: Chemistry of Life, Cell Structure and Function, Cellular Energetics, Cell Communication and Cell Cycle, Heredity, Gene Expression and Regulation, Natural Selection, and Ecology.

Which AP Biology unit is weighted most heavily on the exam?

Unit 7 (Natural Selection) is the most heavily weighted at 13-20% of the multiple-choice section, followed by Units 3 and 6 at 12-16% each. Units 1 (Chemistry of Life) and 5 (Heredity) are the smallest at 8-11% each.

How is the AP Biology exam scored?

AP Biology is scored on a 1-5 scale. A score of 3 is generally considered passing, and many colleges grant credit or placement for a 3, 4, or 5, though policies vary by institution.

Can I use a calculator on the AP Biology exam?

Yes. A four-function (with square root), scientific, or graphing calculator is permitted on both the multiple-choice and free-response sections of the AP Biology exam.

What does the AP Biology free-response section look like?

Section II has 6 free-response questions: 2 long questions (one emphasizing interpreting and evaluating experimental results, one on analyzing a model or visual representation) and 4 short questions.