ADVANCED PLACEMENT BIOLOGY
AP Biology Exam A+
2026/2027
AP Exam with Questions & Verified Answers 2026/2027 — A+ Verified
A+ QUESTIONS 4 SECTIONS 100% RATIONALES
VERIFIED COVERED INCLUDED
CATEGORIES
■ Section 1: Chemistry of Life & Cell Structure/Function
■ Section 2: Cellular Energetics & Cell Communication/Cycle
■ Section 3: Heredity & Gene Expression/Regulation
■ Section 4: Natural Selection & Ecology
Examination Specifications
• Question Format: Multiple Choice (A–D)
• Total Marks: 1 mark per question
• Passing Score: 70% (approx; AP scale 1–5, score 3+ considered passing)
• Cognitive Level: Application & Analysis
• Content aligned to the AP Biology Course and Exam Description units.
STUVIAACTUALEXAM
STUVIAACTUALEXAM Page 1
, SECTION 1: Chemistry of Life & Cell Structure / Function
Q1.
A researcher isolates a macromolecule from a bacterial cell and finds that it is composed of a glycerol backbone linked
to two fatty acid chains and a phosphate group. When placed in aqueous solution the molecules spontaneously form a
bilayer. Which class of macromolecule has been isolated, and what cellular structure does this property enable?
A. Steroid; hormone signaling across the nuclear envelope
B. Triglyceride; energy storage droplets in the cytoplasm
C. Phospholipid; the selectively permeable plasma membrane
D. Polysaccharide; structural support of the cell wall
Correct Answer: C
Rationale: The described structure is a phospholipid. Amphipathic phospholipids spontaneously arrange into bilayers in water,
forming the foundation of the plasma membrane and enabling selective permeability.
Q2.
In an experiment, an enzyme-catalyzed reaction proceeds rapidly at 37 °C and pH 7.2. When the same reaction
mixture is heated to 75 °C for five minutes and then returned to 37 °C, the reaction rate remains near zero. What
molecular change best explains the permanent loss of activity?
A. The enzyme’s primary sequence of amino acids was hydrolyzed
B. Competitive inhibitors permanently occupied the active site
C. Substrate molecules were permanently altered by the elevated temperature
D. Heat disrupted hydrogen bonds and hydrophobic interactions, denaturing the tertiary structure
Correct Answer: D
Rationale: High temperature breaks weak interactions that maintain tertiary (and quaternary) structure, irreversibly denaturing the
enzyme so that the active site is lost even after cooling.
Q3.
A student compares two solutions separated by a selectively permeable membrane. Solution A contains 0.3 M sucrose
and Solution B contains 0.1 M sucrose. After equilibration, which statement correctly describes the movement of water
and the resulting osmotic condition of the cells if living plant cells were placed in Solution A?
A. Water moves from A to B; plant cells become turgid
B. No net water movement occurs; plant cells remain flaccid
C. Water moves from B to A; plant cells become plasmolyzed
D. Sucrose moves from A to B until concentrations equalize
Correct Answer: C
Rationale: Solution A is hypertonic relative to B, so water flows toward A. Plant cells placed in hypertonic Solution A lose water and
plasmolyze.
Q4.
Electron micrographs of a eukaryotic cell show a network of membranous sacs continuous with the nuclear envelope;
ribosomes are attached to portions of these membranes. Newly synthesized polypeptides are observed entering the
lumen of this organelle. Which organelle is described, and what is its primary role?
A. Lysosome; hydrolysis of macromolecules
B. Golgi apparatus; final packaging and secretion of proteins
C. Smooth endoplasmic reticulum; lipid synthesis and detoxification
D. Rough endoplasmic reticulum; co-translational import and folding of secreted or membrane proteins
Correct Answer: D
Rationale: Ribosome-studded membranes continuous with the nuclear envelope constitute the rough ER, the site where proteins
destined for secretion or membranes are synthesized and initially folded.
STUVIAACTUALEXAM Page 2
, Q5.
A mutant yeast strain is unable to acidify its vacuoles. As a result, many hydrolytic enzymes remain inactive. Which
class of organelle is functionally compromised, and what cellular process is most directly impaired?
A. Lysosomes (or vacuoles); intracellular digestion of macromolecules and damaged organelles
B. Chloroplasts; carbon fixation in the Calvin cycle
C. Peroxisomes; oxidation of fatty acids
D. Mitochondria; ATP synthesis via oxidative phosphorylation
Correct Answer: A
Rationale: Vacuolar/lysosomal acidification is required for optimal activity of acid hydrolases. Without it, degradation of
macromolecules and autophagy are impaired.
Q6.
Researchers label newly synthesized proteins in a mammalian cell and track their movement. Within minutes the label
appears in the cis-Golgi, then later in the trans-Golgi, and finally in secretory vesicles. What does this sequence
demonstrate about the secretory pathway?
A. Proteins move vectorially from ER to Golgi to secretory vesicles in a polarized fashion
B. Secretory vesicles form directly from the nuclear envelope
C. The Golgi is the site of protein synthesis and the ER only stores finished proteins
D. Proteins are synthesized on free ribosomes and then diffuse randomly
Correct Answer: A
Rationale: The observed progression reflects the canonical secretory pathway: rough ER → cis-Golgi → medial/trans-Golgi →
secretory vesicles, demonstrating directional vesicular transport.
Q7.
A water molecule forms hydrogen bonds with surrounding water molecules. When a nonpolar solute such as a
hydrocarbon is introduced, the surrounding water molecules form a more ordered cage-like structure. Which
thermodynamic consequence contributes to the low solubility of hydrocarbons in water?
A. An increase in entropy of the solvent that favors mixing
B. Formation of covalent bonds between water and the hydrocarbon
C. An increase in the enthalpy of the hydrocarbon itself
D. A decrease in solvent entropy that makes the hydrophobic effect unfavorable unless offset by other interactions
Correct Answer: D
Rationale: Ordering of water around nonpolar solutes decreases solvent entropy, making dissolution of hydrophobic molecules
thermodynamically unfavorable (the hydrophobic effect).
Q8.
A cell is treated with a drug that blocks the function of the sodium-potassium pump. After several minutes the
intracellular sodium concentration rises and the membrane potential declines. Which additional process is most likely to
be impaired as a secondary consequence?
A. Passive diffusion of oxygen across the membrane
B. Synthesis of ATP by substrate-level phosphorylation in glycolysis
C. Secondary active transport of glucose that depends on the sodium gradient
D. Transcription of ribosomal RNA in the nucleolus
Correct Answer: C
Rationale: The Na+/K+ pump maintains the sodium electrochemical gradient used by many secondary active transporters (e.g.,
SGLT). When the gradient collapses, coupled glucose uptake declines.
STUVIAACTUALEXAM Page 3
AP Biology Exam A+
2026/2027
AP Exam with Questions & Verified Answers 2026/2027 — A+ Verified
A+ QUESTIONS 4 SECTIONS 100% RATIONALES
VERIFIED COVERED INCLUDED
CATEGORIES
■ Section 1: Chemistry of Life & Cell Structure/Function
■ Section 2: Cellular Energetics & Cell Communication/Cycle
■ Section 3: Heredity & Gene Expression/Regulation
■ Section 4: Natural Selection & Ecology
Examination Specifications
• Question Format: Multiple Choice (A–D)
• Total Marks: 1 mark per question
• Passing Score: 70% (approx; AP scale 1–5, score 3+ considered passing)
• Cognitive Level: Application & Analysis
• Content aligned to the AP Biology Course and Exam Description units.
STUVIAACTUALEXAM
STUVIAACTUALEXAM Page 1
, SECTION 1: Chemistry of Life & Cell Structure / Function
Q1.
A researcher isolates a macromolecule from a bacterial cell and finds that it is composed of a glycerol backbone linked
to two fatty acid chains and a phosphate group. When placed in aqueous solution the molecules spontaneously form a
bilayer. Which class of macromolecule has been isolated, and what cellular structure does this property enable?
A. Steroid; hormone signaling across the nuclear envelope
B. Triglyceride; energy storage droplets in the cytoplasm
C. Phospholipid; the selectively permeable plasma membrane
D. Polysaccharide; structural support of the cell wall
Correct Answer: C
Rationale: The described structure is a phospholipid. Amphipathic phospholipids spontaneously arrange into bilayers in water,
forming the foundation of the plasma membrane and enabling selective permeability.
Q2.
In an experiment, an enzyme-catalyzed reaction proceeds rapidly at 37 °C and pH 7.2. When the same reaction
mixture is heated to 75 °C for five minutes and then returned to 37 °C, the reaction rate remains near zero. What
molecular change best explains the permanent loss of activity?
A. The enzyme’s primary sequence of amino acids was hydrolyzed
B. Competitive inhibitors permanently occupied the active site
C. Substrate molecules were permanently altered by the elevated temperature
D. Heat disrupted hydrogen bonds and hydrophobic interactions, denaturing the tertiary structure
Correct Answer: D
Rationale: High temperature breaks weak interactions that maintain tertiary (and quaternary) structure, irreversibly denaturing the
enzyme so that the active site is lost even after cooling.
Q3.
A student compares two solutions separated by a selectively permeable membrane. Solution A contains 0.3 M sucrose
and Solution B contains 0.1 M sucrose. After equilibration, which statement correctly describes the movement of water
and the resulting osmotic condition of the cells if living plant cells were placed in Solution A?
A. Water moves from A to B; plant cells become turgid
B. No net water movement occurs; plant cells remain flaccid
C. Water moves from B to A; plant cells become plasmolyzed
D. Sucrose moves from A to B until concentrations equalize
Correct Answer: C
Rationale: Solution A is hypertonic relative to B, so water flows toward A. Plant cells placed in hypertonic Solution A lose water and
plasmolyze.
Q4.
Electron micrographs of a eukaryotic cell show a network of membranous sacs continuous with the nuclear envelope;
ribosomes are attached to portions of these membranes. Newly synthesized polypeptides are observed entering the
lumen of this organelle. Which organelle is described, and what is its primary role?
A. Lysosome; hydrolysis of macromolecules
B. Golgi apparatus; final packaging and secretion of proteins
C. Smooth endoplasmic reticulum; lipid synthesis and detoxification
D. Rough endoplasmic reticulum; co-translational import and folding of secreted or membrane proteins
Correct Answer: D
Rationale: Ribosome-studded membranes continuous with the nuclear envelope constitute the rough ER, the site where proteins
destined for secretion or membranes are synthesized and initially folded.
STUVIAACTUALEXAM Page 2
, Q5.
A mutant yeast strain is unable to acidify its vacuoles. As a result, many hydrolytic enzymes remain inactive. Which
class of organelle is functionally compromised, and what cellular process is most directly impaired?
A. Lysosomes (or vacuoles); intracellular digestion of macromolecules and damaged organelles
B. Chloroplasts; carbon fixation in the Calvin cycle
C. Peroxisomes; oxidation of fatty acids
D. Mitochondria; ATP synthesis via oxidative phosphorylation
Correct Answer: A
Rationale: Vacuolar/lysosomal acidification is required for optimal activity of acid hydrolases. Without it, degradation of
macromolecules and autophagy are impaired.
Q6.
Researchers label newly synthesized proteins in a mammalian cell and track their movement. Within minutes the label
appears in the cis-Golgi, then later in the trans-Golgi, and finally in secretory vesicles. What does this sequence
demonstrate about the secretory pathway?
A. Proteins move vectorially from ER to Golgi to secretory vesicles in a polarized fashion
B. Secretory vesicles form directly from the nuclear envelope
C. The Golgi is the site of protein synthesis and the ER only stores finished proteins
D. Proteins are synthesized on free ribosomes and then diffuse randomly
Correct Answer: A
Rationale: The observed progression reflects the canonical secretory pathway: rough ER → cis-Golgi → medial/trans-Golgi →
secretory vesicles, demonstrating directional vesicular transport.
Q7.
A water molecule forms hydrogen bonds with surrounding water molecules. When a nonpolar solute such as a
hydrocarbon is introduced, the surrounding water molecules form a more ordered cage-like structure. Which
thermodynamic consequence contributes to the low solubility of hydrocarbons in water?
A. An increase in entropy of the solvent that favors mixing
B. Formation of covalent bonds between water and the hydrocarbon
C. An increase in the enthalpy of the hydrocarbon itself
D. A decrease in solvent entropy that makes the hydrophobic effect unfavorable unless offset by other interactions
Correct Answer: D
Rationale: Ordering of water around nonpolar solutes decreases solvent entropy, making dissolution of hydrophobic molecules
thermodynamically unfavorable (the hydrophobic effect).
Q8.
A cell is treated with a drug that blocks the function of the sodium-potassium pump. After several minutes the
intracellular sodium concentration rises and the membrane potential declines. Which additional process is most likely to
be impaired as a secondary consequence?
A. Passive diffusion of oxygen across the membrane
B. Synthesis of ATP by substrate-level phosphorylation in glycolysis
C. Secondary active transport of glucose that depends on the sodium gradient
D. Transcription of ribosomal RNA in the nucleolus
Correct Answer: C
Rationale: The Na+/K+ pump maintains the sodium electrochemical gradient used by many secondary active transporters (e.g.,
SGLT). When the gradient collapses, coupled glucose uptake declines.
STUVIAACTUALEXAM Page 3
