10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The AP Biology exam has 66 questions and runs 3 hours.
These 10 free AP Biology questions are organized by exam domain, so you can see how each part of the Advanced Placement Biology blueprint is tested. Reveal the answer and explanation under each question.
A redwood tree transports water from its roots to leaves more than 60 meters above the ground, and no ATP is expended within the xylem to move it. Which explanation best accounts for this?
Correct answer: A - Cohesion between water molecules and adhesion to the xylem walls maintain an unbroken column
A globular enzyme contains a nonpolar amino acid buried in its hydrophobic interior. A mutation replaces this amino acid with one that has a charged R group. Which outcome is most likely?
Correct answer: D - Tertiary structure is disrupted, altering the shape of the active site and reducing activity
A cube-shaped cell has a side length of 4 micrometers. A second cube-shaped cell has a side length of 2 micrometers. Compared with the smaller cell, the larger cell has:
Correct answer: B - half the surface area-to-volume ratio, so each unit of cytoplasm is served by less membrane area
A plant cell has a solute potential of -0.7 MPa and a pressure potential of +0.3 MPa. It is placed in an open beaker containing a solution with a water potential of -0.6 MPa. Recall that water potential = pressure potential + solute potential. What is the net movement of water?
Correct answer: C - Out of the cell, since the cell's water potential of -0.4 MPa is less negative
A researcher measured the rate of an enzyme-catalyzed reaction at four substrate concentrations, first without an inhibitor and then with an inhibitor present. Substrate (mM) | Rate without inhibitor | Rate with inhibitor 1 | 20 | 8 5 | 60 | 30 20 | 95 | 78 50 | 100 | 98 (Rates in micromoles per minute.) Which conclusion is best supported by these data?
Correct answer: A - The inhibitor is competitive, because increasing substrate concentration overcomes its effect
An herbicide blocks the transfer of electrons from photosystem II to the electron transport chain in the thylakoid membrane. What is the most likely immediate effect on the Calvin cycle?
Correct answer: B - Carbon fixation slows, because the supply of ATP and NADPH to the stroma is reduced
A chemical compound carries protons across the inner mitochondrial membrane, bypassing ATP synthase. Cells treated with this compound continue to consume oxygen at a high rate but grow poorly. Which statement best explains these observations?
Correct answer: D - The proton gradient collapses, so electron transport continues but little ATP is produced
A student examines 500 cells from an onion root tip and finds that 45 of them are in some stage of mitosis. The complete cell cycle for these cells lasts 24 hours. Approximately how much time does an average cell spend in interphase?
Correct answer: C - About 21.8 hours
A hormone binds to a membrane receptor, activating a phosphorylation cascade that ends with the activation of a transcription factor. In a mutant cell line, the transcription factor is active even when no hormone is present, and adding a drug that blocks the receptor's hormone-binding site does not reduce this activity. Where is the mutation most likely located?
Correct answer: D - In a kinase downstream of the receptor, locking it in its active form
A geneticist crosses two heterozygous pea plants and obtains 220 tall and 60 short offspring. Testing the fit to an expected 3:1 ratio, she calculates a chi-square value of 1.90. The critical value at p = 0.05 with 1 degree of freedom is 3.84. What is the correct conclusion?
Correct answer: A - Fail to reject the null hypothesis; the deviation is most likely due to chance
The AP Biology exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more AP Biology questions with explanations.
Continue in the free practice test →
View plans