BIO111 Exam 1 Actual Exam V2 | BIO111 General Biology (BIO111
Exam 1) | University of California, Los Angeles
1. A scientist observes that a specific species of plant grows taller in the sunlight than in the
shade. What is the most appropriate next step in the scientific method?
A. Develop a mathematical model.
B. Publish the observation in a journal.
C. Formulate a testable hypothesis.
D. Conduct a double-blind experiment.
Answer: C
Rationale: The scientific method begins with observation, which naturally leads to a
question. The next logical step is to formulate a hypothesis, which is a tentative explanation
for the observation. This hypothesis must be testable through further experimentation and
data collection.
2. In a controlled experiment, which of the following is the factor that is being manipulated
by the researcher?
A. Dependent variable
B. Negative control
C. Control group
D. Independent variable
Answer: D
Rationale: The independent variable is the specific factor that a researcher changes or
manipulates to observe its effects. In contrast, the dependent variable is what is measured
or observed as a result of those changes. A well-designed experiment ensures that all other
variables are kept constant to isolate the effect of the independent variable.
3. Which of the following statements best distinguishes a scientific theory from a hypothesis?
A. A theory is a guess, while a hypothesis is a fact.
B. A hypothesis is supported by a large body of evidence.
C. A theory is much broader in scope than a hypothesis.
D. Theories are always proven to be 100% true.
Answer: C
,Rationale: A hypothesis is a specific, testable prediction regarding a narrow set of
observations. A scientific theory, however, is a comprehensive explanation for a broad
range of phenomena that is supported by extensive evidence. Unlike common usage,
scientific theories are robust frameworks rather than mere guesses.
4. Which property of water allows it to move upward through the vessels of a tall tree against
gravity?
A. High specific heat
B. Low density of ice
C. Cohesion and adhesion
D. Versatile solvent properties
Answer: C
Rationale: Cohesion refers to the attraction between water molecules due to hydrogen
bonding, while adhesion is the attraction to the walls of the xylem. Together, these
properties facilitate capillary action, allowing water to reach high elevations in plants. This
process is essential for the survival of terrestrial vegetation.
5. Why does ice float on liquid water?
A. Ice contains more kinetic energy than liquid water.
B. Water molecules in ice are packed more tightly together.
C. Hydrogen bonds break down at low temperatures.
D. The crystalline lattice of ice is less dense than liquid water.
Answer: D
Rationale: As water freezes, each molecule forms four stable hydrogen bonds with its
neighbors, creating a crystalline lattice. This structure pushes the molecules further apart
compared to their arrangement in the liquid state, making ice less dense. This unique
property prevents lakes from freezing solid, protecting aquatic life during winter.
6. A solution with a pH of 4 has how many more hydrogen ions (H+) than a solution with a pH
of 6?
A. 2 times
B. 100 times
C. 20 times
D. 1000 times
Answer: B
, Rationale: The pH scale is logarithmic, meaning each whole number change represents a
ten-fold difference in hydrogen ion concentration. A shift from pH 6 to pH 4 is a difference
of two units, which equals 10 to the power of 2. Therefore, the pH 4 solution is 100 times
more acidic than the pH 6 solution.
7. Which type of bond involves the sharing of electrons between two atoms?
A. Covalent bond
B. Hydrogen bond
C. Ionic bond
D. Van der Waals interaction
Answer: A
Rationale: Covalent bonds are formed when two atoms share one or more pairs of valence
electrons to achieve stability. This is the primary type of bond that holds together the
backbones of biological macromolecules. Covalent bonds can be polar or nonpolar
depending on the electronegativity of the participating atoms.
8. What is the primary function of a buffer in biological systems?
A. To speed up chemical reactions
B. To provide energy for the cell
C. To maintain a relatively constant pH
D. To act as a structural component of membranes
Answer: C
Rationale: Buffers are substances that minimize changes in the concentration of H+ and
OH- in a solution. They typically consist of a weak acid and its corresponding base, which
can either donate or accept protons as needed. Maintaining pH stability is critical for the
proper functioning of enzymes and other proteins in the body.
9. Which functional group is characteristic of alcohols and helps increase solubility in water?
A. Carboxyl group (-COOH)
B. Amino group (-NH2)
C. Hydroxyl group (-OH)
D. Phosphate group (-PO4)
Answer: C
Rationale: The hydroxyl group consists of an oxygen atom bonded to a hydrogen atom,
making the molecule polar. This polarity allows alcohols to form hydrogen bonds with
Exam 1) | University of California, Los Angeles
1. A scientist observes that a specific species of plant grows taller in the sunlight than in the
shade. What is the most appropriate next step in the scientific method?
A. Develop a mathematical model.
B. Publish the observation in a journal.
C. Formulate a testable hypothesis.
D. Conduct a double-blind experiment.
Answer: C
Rationale: The scientific method begins with observation, which naturally leads to a
question. The next logical step is to formulate a hypothesis, which is a tentative explanation
for the observation. This hypothesis must be testable through further experimentation and
data collection.
2. In a controlled experiment, which of the following is the factor that is being manipulated
by the researcher?
A. Dependent variable
B. Negative control
C. Control group
D. Independent variable
Answer: D
Rationale: The independent variable is the specific factor that a researcher changes or
manipulates to observe its effects. In contrast, the dependent variable is what is measured
or observed as a result of those changes. A well-designed experiment ensures that all other
variables are kept constant to isolate the effect of the independent variable.
3. Which of the following statements best distinguishes a scientific theory from a hypothesis?
A. A theory is a guess, while a hypothesis is a fact.
B. A hypothesis is supported by a large body of evidence.
C. A theory is much broader in scope than a hypothesis.
D. Theories are always proven to be 100% true.
Answer: C
,Rationale: A hypothesis is a specific, testable prediction regarding a narrow set of
observations. A scientific theory, however, is a comprehensive explanation for a broad
range of phenomena that is supported by extensive evidence. Unlike common usage,
scientific theories are robust frameworks rather than mere guesses.
4. Which property of water allows it to move upward through the vessels of a tall tree against
gravity?
A. High specific heat
B. Low density of ice
C. Cohesion and adhesion
D. Versatile solvent properties
Answer: C
Rationale: Cohesion refers to the attraction between water molecules due to hydrogen
bonding, while adhesion is the attraction to the walls of the xylem. Together, these
properties facilitate capillary action, allowing water to reach high elevations in plants. This
process is essential for the survival of terrestrial vegetation.
5. Why does ice float on liquid water?
A. Ice contains more kinetic energy than liquid water.
B. Water molecules in ice are packed more tightly together.
C. Hydrogen bonds break down at low temperatures.
D. The crystalline lattice of ice is less dense than liquid water.
Answer: D
Rationale: As water freezes, each molecule forms four stable hydrogen bonds with its
neighbors, creating a crystalline lattice. This structure pushes the molecules further apart
compared to their arrangement in the liquid state, making ice less dense. This unique
property prevents lakes from freezing solid, protecting aquatic life during winter.
6. A solution with a pH of 4 has how many more hydrogen ions (H+) than a solution with a pH
of 6?
A. 2 times
B. 100 times
C. 20 times
D. 1000 times
Answer: B
, Rationale: The pH scale is logarithmic, meaning each whole number change represents a
ten-fold difference in hydrogen ion concentration. A shift from pH 6 to pH 4 is a difference
of two units, which equals 10 to the power of 2. Therefore, the pH 4 solution is 100 times
more acidic than the pH 6 solution.
7. Which type of bond involves the sharing of electrons between two atoms?
A. Covalent bond
B. Hydrogen bond
C. Ionic bond
D. Van der Waals interaction
Answer: A
Rationale: Covalent bonds are formed when two atoms share one or more pairs of valence
electrons to achieve stability. This is the primary type of bond that holds together the
backbones of biological macromolecules. Covalent bonds can be polar or nonpolar
depending on the electronegativity of the participating atoms.
8. What is the primary function of a buffer in biological systems?
A. To speed up chemical reactions
B. To provide energy for the cell
C. To maintain a relatively constant pH
D. To act as a structural component of membranes
Answer: C
Rationale: Buffers are substances that minimize changes in the concentration of H+ and
OH- in a solution. They typically consist of a weak acid and its corresponding base, which
can either donate or accept protons as needed. Maintaining pH stability is critical for the
proper functioning of enzymes and other proteins in the body.
9. Which functional group is characteristic of alcohols and helps increase solubility in water?
A. Carboxyl group (-COOH)
B. Amino group (-NH2)
C. Hydroxyl group (-OH)
D. Phosphate group (-PO4)
Answer: C
Rationale: The hydroxyl group consists of an oxygen atom bonded to a hydrogen atom,
making the molecule polar. This polarity allows alcohols to form hydrogen bonds with
