AP Biology Practice Test- 60 Questions With Answers
Questions 1–4 refer to the following information.
A scientist is studying the effect of light intensity on the rate of photosynthesis in Elodea, an aquatic plant. In a controlled experiment, she places equal-sized Elodea samples in identical beakers and exposes them to varying light intensities. The rate of photosynthesis is measured by counting oxygen bubbles released per minute.
1. Which variable is the dependent variable in this experiment?
A. Light intensity
B. Type of plant
C. Rate of oxygen production
D. Temperature of water
2. What would be a proper control in this experiment?
A. A sample of Elodea placed in the dark
B. Using a different plant species
C. Using larger beakers
D. Adding carbon dioxide to the water
3. Which of the following would likely increase the rate of photosynthesis?
A. Decreasing temperature
B. Increasing light intensity
C. Lowering CO₂ concentration
D. Decreasing water availability
4. If the rate of bubble production plateaus at high light intensity, the limiting factor is most likely:
A. Light
B. Temperature
C. Water
D. Enzyme saturation
SECTION I: MULTIPLE CHOICE (continued)
5. Which of the following organelles is primarily responsible for producing ATP in eukaryotic cells?
A. Ribosome
B. Nucleus
C. Mitochondrion
D. Golgi apparatus
6. The endosymbiotic theory explains the origin of:
A. Ribosomes and lysosomes
B. Chloroplasts and mitochondria
C. Vacuoles and nuclei
D. Peroxisomes and centrioles
7. Which of the following best describes the role of tRNA during translation?
A. Carries mRNA from nucleus to ribosome
B. Catalyzes peptide bond formation
C. Brings amino acids to the ribosome
D. Unwinds DNA strands
8. If a cell has a high surface area-to-volume ratio, it is likely:
A. Inefficient at material exchange
B. Large in size
C. More efficient at diffusion
D. Less metabolically active
9. Which macromolecule is primarily responsible for catalyzing chemical reactions?
A. Nucleic acids
B. Lipids
C. Proteins
D. Carbohydrates
10. A mutation causes a substitution of a hydrophilic amino acid for a hydrophobic one. Which of the following is most likely affected?
A. mRNA transcription
B. Protein secondary structure
C. Protein folding and function
D. DNA replication
11. In a population in Hardy-Weinberg equilibrium, the frequency of the recessive allele is 0.2. What is the expected frequency of heterozygotes?
A. 0.04
B. 0.16
C. 0.32
D. 0.64
12. Which process increases genetic variation in prokaryotes?
A. Binary fission
B. Conjugation
C. Mitosis
D. Budding
13. The primary function of the light-dependent reactions of photosynthesis is to:
A. Convert CO₂ into glucose
B. Produce ATP and NADPH
C. Fix carbon into RuBP
D. Release oxygen by breaking down glucose
14. What occurs during anaphase of mitosis?
A. Chromosomes align at the metaphase plate
B. Sister chromatids separate and move to opposite poles
C. Nuclear envelope reforms
D. DNA is replicated
15. Which of the following hormones is produced in response to high blood glucose levels?
A. Glucagon
B. Insulin
C. Cortisol
D. Epinephrine
16. Which of the following is an example of a density-dependent limiting factor?
A. Natural disasters
B. Human encroachment
C. Disease
D. Temperature extremes
17. A keystone species:
A. Is always the most numerous in an ecosystem
B. Has little effect on its ecosystem
C. Disrupts ecosystems when introduced
D. Has a disproportionate impact on community structure
18. Which molecule is directly involved in cell signaling and acts as a second messenger?
A. DNA
B. ATP
C. cAMP
D. Glucose
19. Which of the following is a characteristic of active transport?
A. Moves substances along the concentration gradient
B. Does not require ATP
C. Moves substances against the concentration gradient
D. Occurs only in prokaryotes
20. Which of the following best describes the lac operon in E. coli?
A. Always off regardless of lactose presence
B. Turned on when lactose is absent
C. Regulated based on glucose and lactose levels
D. Active only in eukaryotic cells
21. DNA replication is described as:
A. Conservative
B. Semi-conservative
C. Dispersive
D. Redundant
22. Which cell type is responsible for humoral immunity?
A. T-helper cells
B. Cytotoxic T cells
C. B cells
D. Macrophages
23. Which of the following is a direct result of natural selection?
A. Acquisition of traits during an organism’s lifetime
B. Development of adaptations that improve survival
C. Increased mutations in a population
D. Equal survival of all phenotypes
24. Which statement best describes allosteric regulation of an enzyme?
A. Enzyme activity is blocked at the active site
B. A molecule binds and alters the enzyme’s shape and activity
C. ATP is hydrolyzed at the enzyme’s surface
D. Enzyme denatures due to heat
SECTION I: MULTIPLE CHOICE (continued)
25. Which of the following structures is common to both prokaryotic and eukaryotic cells?
A. Nucleus
B. Mitochondria
C. Ribosomes
D. Endoplasmic reticulum
26. A population of insects becomes resistant to a pesticide over time. This is an example of:
A. Genetic drift
B. Natural selection
C. Bottleneck effect
D. Gene flow
27. Which process ensures that gametes receive only one allele of each gene?
A. DNA replication
B. Crossing over
C. Meiosis I
D. Meiosis II
28. Which of the following best explains why water has a high specific heat?
A. Hydrogen bonding between water molecules
B. Nonpolar covalent bonds in water
C. Ionic interactions with solutes
D. Hydrophobic interactions
29. Which of the following events increases genetic variation in meiosis?
A. Cytokinesis
B. DNA replication
C. Independent assortment
D. G1 checkpoint
30. What is the role of NADH and FADH₂ in cellular respiration?
A. Store oxygen for the electron transport chain
B. Act as enzymes in the Krebs cycle
C. Transfer electrons to the electron transport chain
D. Break down glucose in glycolysis
31. Which part of the nephron is primarily responsible for reabsorption of nutrients like glucose and amino acids?
A. Loop of Henle
B. Glomerulus
C. Collecting duct
D. Proximal tubule
32. Which immune cells are primarily involved in attacking infected body cells?
A. B cells
B. Helper T cells
C. Cytotoxic T cells
D. Neutrophils
33. What effect would a mutation that inactivates the p53 gene most likely have?
A. Enhanced DNA repair
B. Increased cell death
C. Loss of cell cycle regulation
D. Suppression of tumor growth
34. Which organelle is most closely associated with protein synthesis?
A. Lysosome
B. Nucleolus
C. Ribosome
D. Peroxisome
35. What is the function of the Calvin cycle in photosynthesis?
A. Convert glucose to ATP
B. Fix carbon into organic molecules
C. Split water to release oxygen
D. Capture sunlight for ATP production
36. During which stage of the cell cycle is DNA replicated?
A. G1 phase
B. G2 phase
C. S phase
D. M phase
37. Which of the following is true about ecological succession?
A. Primary succession occurs after a forest fire
B. Climax communities never change
C. Secondary succession occurs on new volcanic rock
D. Pioneer species help establish conditions for other species
38. Which cellular structure allows plant cells to communicate directly with each other?
A. Tight junctions
B. Gap junctions
C. Plasmodesmata
D. Desmosomes
39. A researcher finds that a mutation affects the production of a transcription factor. What process is directly impacted?
A. Protein degradation
B. DNA replication
C. Gene expression
D. Translation initiation
40. The process of apoptosis is most accurately described as:
A. Cell necrosis due to injury
B. Unregulated cell division
C. Programmed cell death
D. Mutation-induced cancer
41. What is the main function of the Golgi apparatus?
A. DNA replication
B. Protein modification and sorting
C. ATP synthesis
D. Ribosome assembly
42. Which term describes a group of individuals of the same species living in a particular area?
A. Community
B. Ecosystem
C. Population
D. Biome
43. Which structure in the chloroplast is responsible for the light-dependent reactions?
A. Stroma
B. Inner membrane
C. Thylakoid membrane
D. Outer membrane
44. In cellular respiration, which process occurs in the cytoplasm?
A. Krebs cycle
B. Electron transport chain
C. Glycolysis
D. Oxidative phosphorylation
SECTION I: MULTIPLE CHOICE (continued)
45. Which of the following best describes the function of restriction enzymes in biotechnology?
A. Amplify DNA sequences
B. Cut DNA at specific sequences
C. Synthesize RNA from DNA
D. Join DNA fragments together
46. A species with a narrow ecological niche is most likely to:
A. Be a generalist and adapt to many environments
B. Have a stable population size
C. Be highly susceptible to environmental change
D. Outcompete invasive species
47. Which of the following best describes quorum sensing in bacteria?
A. Movement in response to light
B. Communication using electrical impulses
C. Coordinated behavior in response to population density
D. Genetic recombination through transformation
48. In signal transduction pathways, phosphorylation cascades:
A. Always produce cyclic AMP
B. Amplify the signal
C. Inhibit transcription
D. Degrade the signal molecules
49. Which of the following is true about viruses?
A. They are made of only proteins
B. They can reproduce on their own
C. They use host machinery to replicate
D. They are classified as living organisms
50. A woman with type AB blood and a man with type O blood could have children with which blood type(s)?
A. A or B only
B. AB only
C. A, B, AB, or O
D. A, B, or O only
51. Which of the following would be a direct consequence of removing all decomposers from an ecosystem?
A. Increase in herbivore populations
B. Accumulation of organic waste
C. More rapid cycling of nutrients
D. Decrease in atmospheric CO₂
52. What would be the effect of a toxin that blocks voltage-gated sodium channels in neurons?
A. Enhanced neurotransmitter release
B. Prevention of action potential propagation
C. Increased membrane depolarization
D. Rapid muscle contraction
53. The oxygen released during photosynthesis comes from:
A. Carbon dioxide
B. Glucose
C. Water
D. ATP
54. What is the main cause of water’s cohesion and surface tension?
A. Ionic bonds
B. Covalent bonds
C. Hydrogen bonding
D. van der Waals interactions
55. Which evolutionary concept explains why some traits increase in frequency even if they are neutral?
A. Natural selection
B. Genetic drift
C. Artificial selection
D. Adaptive radiation
56. Which of the following best explains why insects are small in size?
A. Their exoskeleton is too soft
B. Their open circulatory system limits oxygen delivery
C. They lack mitochondria
D. Their nervous system is inefficient
57. Which of the following best describes the role of ATP synthase in oxidative phosphorylation?
A. Transfers electrons to NAD⁺
B. Splits glucose into pyruvate
C. Uses H⁺ gradient to make ATP
D. Pumps protons into the intermembrane space
58. In ecology, the term “carrying capacity” refers to:
A. Maximum lifespan of a species
B. Total number of species in a habitat
C. Maximum population size the environment can support
D. Energy transfer between trophic levels
59. Which statement best explains why some genetic disorders are more common in males?
A. Males have two X chromosomes
B. Most genetic disorders are autosomal dominant
C. Males are hemizygous for X-linked genes
D. Females have stronger immune systems
60. Which of the following describes a positive feedback mechanism?
A. Blood glucose regulation by insulin
B. Maintenance of body temperature
C. Uterine contractions during childbirth
D. Kidney filtration rate regulation
Answer Key: Multiple Choice
| Question | Answer | Question | Answer | Question | Answer | ||
|---|---|---|---|---|---|---|---|
| 1 | C | 21 | B | 41 | B | ||
| 2 | A | 22 | C | 42 | C | ||
| 3 | B | 23 | B | 43 | C | ||
| 4 | D | 24 | B | 44 | C | ||
| 5 | C | 25 | C | 45 | B | ||
| 6 | B | 26 | B | 46 | C | ||
| 7 | C | 27 | C | 47 | C | ||
| 8 | C | 28 | A | 48 | B | ||
| 9 | C | 29 | C | 49 | C | ||
| 10 | C | 30 | C | 50 | A | ||
| 11 | C | 31 | D | 51 | B | ||
| 12 | B | 32 | C | 52 | B | ||
| 13 | B | 33 | C | 53 | C | ||
| 14 | B | 34 | C | 54 | C | ||
| 15 | B | 35 | B | 55 | B | ||
| 16 | C | 36 | C | 56 | B | ||
| 17 | D | 37 | D | 57 | C | ||
| 18 | C | 38 | C | 58 | C | ||
| 19 | C | 39 | C | 59 | C | ||
| 20 | C | 40 | C | 60 | C |
AP Biology practice
Question 1: Long Free Response
(25 minutes recommended)
In a study of enzyme activity, students tested how temperature affects the function of catalase, an enzyme that breaks down hydrogen peroxide into water and oxygen.
a. Design an experiment to determine how temperature affects catalase activity. Include your hypothesis, variables, and methods.
b. Predict the results you would expect at very low and very high temperatures. Explain your reasoning using enzyme structure and function.
c. Discuss how denaturation affects enzyme activity. Relate this to the shape of the catalase enzyme.
Question 2: Long Free Response
(25 minutes recommended)
The figure below shows a phylogenetic tree of several primate species.
a. Describe how molecular evidence (e.g., DNA sequences) supports the relationships shown in the phylogenetic tree.
b. Explain how evolutionary processes lead to speciation.
c. Discuss one limitation of using a phylogenetic tree to show evolutionary relationships.
Question 3: Short Free Response
Describe how the structure of the phospholipid bilayer contributes to its function in cell membranes.
Question 4: Short Free Response
Explain how a mutation in the DNA sequence of a gene might lead to a change in the function of the resulting protein.
Question 5: Short Free Response
Describe how negative feedback helps maintain homeostasis. Provide a specific biological example.
Question 6: Short Free Response
Discuss one advantage and one disadvantage of sexual reproduction compared to asexual reproduction.
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