AP Biology practice test
Practice questions for all eight AP Biology units. Answer in your browser and read why each answer is right. Pick a unit to focus on, or take them all.
Question 1 of 25
Water's high specific heat and its cohesion are mainly the result of
Question 2 of 25
When two amino acids join to form a dipeptide, the reaction
Question 3 of 25
A nucleotide is made of
Question 4 of 25
Which structure is found in both prokaryotic and eukaryotic cells?
Question 5 of 25
An animal cell is placed in a hypertonic solution. What happens?
Question 6 of 25
The sodium-potassium pump is an example of
Question 7 of 25
Enzymes speed up chemical reactions by
Question 8 of 25
In cellular respiration, most ATP is made when
Question 9 of 25
The oxygen released during photosynthesis comes from
Question 10 of 25
In many signaling pathways, cyclic AMP (cAMP) acts as a
Question 11 of 25
Mitosis in a diploid cell produces
Question 12 of 25
A mutation disables the protein p53, so damaged cells pass the cell-cycle checkpoints. The most likely result is
Question 13 of 25
Two heterozygous plants (Aa × Aa) are crossed. A is completely dominant. What phenotype ratio is expected in the offspring?
Question 14 of 25
Crossing over between homologous chromosomes happens during
Question 15 of 25
A woman who carries an X-linked recessive disorder has children with an unaffected man. What fraction of their sons are expected to have the disorder?
Question 16 of 25
In eukaryotes, transcription
Question 17 of 25
In the lac operon, when lactose is present
Question 18 of 25
A base substitution changes a codon from GAA to GAG, and both code for glutamic acid. This is a
Question 19 of 25
In a population in Hardy-Weinberg equilibrium, 16% of individuals show the recessive phenotype. What is the frequency of heterozygotes?
Question 20 of 25
Bacteria become resistant to an antibiotic over time because
Question 21 of 25
The human arm, bat wing and whale flipper have the same arrangement of bones. These are
Question 22 of 25
Producers in an ecosystem capture 10,000 kcal of energy. About how much reaches the secondary consumers?
Question 23 of 25
In logistic population growth, the growth rate slows as the population
Question 24 of 25
When sea otters were removed from a kelp forest, sea urchins multiplied and destroyed the kelp. Sea otters are an example of a
Question 25 of 25
Nitrogen fixation is the process in which
AP Biology key terms
Flip through these flashcards to review the terms that come up most often. Use the arrow keys or click a card to flip it.
| Hydrogen bond | Weak attraction between a slightly positive hydrogen and a slightly negative atom, such as oxygen in another water molecule. |
| Dehydration synthesis | Reaction that joins monomers into a polymer and releases water. |
| Surface area to volume ratio | As a cell grows, volume increases faster than surface area, limiting exchange with the environment. |
| Osmosis | Diffusion of water across a selectively permeable membrane toward the higher solute concentration. |
| Chemiosmosis | ATP production driven by H⁺ flowing down its gradient through ATP synthase. |
| Calvin cycle | Light-independent reactions in the stroma that fix CO₂ into sugar using ATP and NADPH. |
| Signal transduction | The chain of steps that converts a signal at the cell surface into a response inside the cell. |
| Apoptosis | Programmed cell death. |
| Nondisjunction | Failure of chromosomes to separate correctly, producing gametes with the wrong chromosome number. |
| Codon | Three-nucleotide sequence in mRNA that specifies an amino acid or a stop signal. |
| Operon | Cluster of genes in prokaryotes controlled by a single promoter and operator. |
| Genetic drift | Random change in allele frequencies, strongest in small populations. |
| Hardy-Weinberg equilibrium | Allele frequencies stay constant without mutation, migration, selection, drift or nonrandom mating: p² + 2pq + q² = 1. |
| Carrying capacity (K) | Maximum population size an environment can support. |
| Trophic level | An organism's position in a food chain, such as producer, primary consumer or secondary consumer. |
See all 15 cards
Hydrogen bondWeak attraction between a slightly positive hydrogen and a slightly negative atom, such as oxygen in another water molecule.
Dehydration synthesisReaction that joins monomers into a polymer and releases water.
Surface area to volume ratioAs a cell grows, volume increases faster than surface area, limiting exchange with the environment.
OsmosisDiffusion of water across a selectively permeable membrane toward the higher solute concentration.
ChemiosmosisATP production driven by H⁺ flowing down its gradient through ATP synthase.
Calvin cycleLight-independent reactions in the stroma that fix CO₂ into sugar using ATP and NADPH.
Signal transductionThe chain of steps that converts a signal at the cell surface into a response inside the cell.
ApoptosisProgrammed cell death.
NondisjunctionFailure of chromosomes to separate correctly, producing gametes with the wrong chromosome number.
CodonThree-nucleotide sequence in mRNA that specifies an amino acid or a stop signal.
OperonCluster of genes in prokaryotes controlled by a single promoter and operator.
Genetic driftRandom change in allele frequencies, strongest in small populations.
Hardy-Weinberg equilibriumAllele frequencies stay constant without mutation, migration, selection, drift or nonrandom mating: p² + 2pq + q² = 1.
Carrying capacity (K)Maximum population size an environment can support.
Trophic levelAn organism's position in a food chain, such as producer, primary consumer or secondary consumer.
About the AP Biology exam
- Section I: 60 multiple-choice questions in 90 minutes, 50% of the score.
- Section II: 6 free-response questions in 90 minutes, 50%: 2 long questions and 4 short ones.
- Natural selection, gene expression and cellular energetics are among the most heavily weighted units.
Questions
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