BIO111 Exam 2 Actual Exam V1 | BIO111 General Biology (BIO111
Exam 2) | University of California, Los Angeles
1. Which of the following describes the first law of thermodynamics?
A. Energy transfer increases the entropy of the universe.
B. Energy cannot be created or destroyed, only transformed.
C. Systems move toward a state of maximum disorder.
D. Chemical reactions always result in a loss of heat.
Answer: B
Rationale: The first law of thermodynamics states that the total amount of energy in a
closed system remains constant. It can change from one form to another, such as light
energy being converted into chemical energy during photosynthesis. However, no new
energy is ever created, and no energy is completely destroyed during these biological
processes.
2. A reaction with a negative Delta G is best described as:
A. Endergonic and non-spontaneous
B. At equilibrium
C. Exergonic and spontaneous
D. Endothermic and requiring energy
Answer: C
Rationale: Free energy (G) is the portion of a system’s energy that can perform work when
temperature and pressure are uniform. A negative Delta G indicates that the products have
less free energy than the reactants, making the reaction exergonic. Such reactions occur
spontaneously because they release energy into their surroundings.
3. How do enzymes speed up chemical reactions in a cell?
A. By increasing the temperature of the reaction environment
B. By providing the necessary activation energy
C. By changing the Delta G of the reaction
D. By lowering the activation energy barrier
Answer: D
,Rationale: Enzymes act as biological catalysts by stabilizing the transition state of a
substrate. They reduce the amount of activation energy required for a reaction to proceed
at a significant rate. It is important to note that enzymes do not change the total free energy
change (Delta G) of the reaction itself.
4. Which site on an enzyme does a competitive inhibitor bind to?
A. The allosteric site
B. The phosphate binding site
C. The regulatory site
D. The active site
Answer: D
Rationale: Competitive inhibitors structurally resemble the substrate and compete for the
same physical location on the enzyme. By binding to the active site, they block the substrate
from entering and reacting. This type of inhibition can often be overcome by increasing the
concentration of the actual substrate.
5. In cellular respiration, what is the net yield of ATP produced per glucose molecule during
glycolysis?
A. 1 ATP
B. 32 ATP
C. 4 ATP
D. 2 ATP
Answer: D
Rationale: Glycolysis consists of an energy investment phase and an energy payoff phase.
While 4 ATP molecules are produced total, 2 ATP molecules are consumed during the
initial steps. Therefore, the net gain for the cell is exactly 2 ATP molecules per molecule of
glucose processed.
6. What is the primary role of NAD+ in cellular respiration?
A. To act as a final electron acceptor in the ETC
B. To provide energy for the sodium-potassium pump
C. To act as an electron carrier (oxidizing agent)
D. To catalyze the conversion of glucose to pyruvate
Answer: C
Rationale: NAD+ functions as a coenzyme that accepts electrons from organic molecules,
becoming reduced to NADH. It carries these high-energy electrons to the electron transport
, chain where they are used to drive ATP synthesis. Without NAD+, the redox reactions of
glycolysis and the citric acid cycle would cease to function.
7. Where does the Citric Acid Cycle (Krebs Cycle) occur in eukaryotic cells?
A. Cytosol
B. Inner mitochondrial membrane
C. Mitochondrial matrix
D. Intermembrane space
Answer: C
Rationale: After pyruvate is transported into the mitochondria and converted to Acetyl-
CoA, it enters the citric acid cycle. This series of reactions takes place within the
mitochondrial matrix, the innermost compartment. The matrix contains all the necessary
enzymes and substrates to facilitate the oxidation of carbon compounds.
8. During the electron transport chain, what is the direct source of energy that powers ATP
synthase?
A. The hydrolysis of ATP
B. Electrons flowing through the chain
C. A proton (H+) gradient across the inner membrane
D. The oxidation of NADH to NAD+
Answer: C
Rationale: The movement of electrons through the transport chain pumps protons from
the matrix into the intermembrane space. This creates an electrochemical gradient, known
as the proton-motive force. As protons flow back into the matrix through ATP synthase, the
kinetic energy of their movement is used to phosphorylate ADP into ATP.
9. What is the final electron acceptor in aerobic cellular respiration?
A. Oxygen
B. Carbon dioxide
C. Water
D. Pyruvate
Answer: A
Rationale: In aerobic organisms, molecular oxygen (O2) serves as the ultimate destination
for electrons traveling down the transport chain. Oxygen has a high electronegativity,
allowing it to pull electrons through the various complexes. When oxygen accepts these
electrons along with protons, it is reduced to form water.
Exam 2) | University of California, Los Angeles
1. Which of the following describes the first law of thermodynamics?
A. Energy transfer increases the entropy of the universe.
B. Energy cannot be created or destroyed, only transformed.
C. Systems move toward a state of maximum disorder.
D. Chemical reactions always result in a loss of heat.
Answer: B
Rationale: The first law of thermodynamics states that the total amount of energy in a
closed system remains constant. It can change from one form to another, such as light
energy being converted into chemical energy during photosynthesis. However, no new
energy is ever created, and no energy is completely destroyed during these biological
processes.
2. A reaction with a negative Delta G is best described as:
A. Endergonic and non-spontaneous
B. At equilibrium
C. Exergonic and spontaneous
D. Endothermic and requiring energy
Answer: C
Rationale: Free energy (G) is the portion of a system’s energy that can perform work when
temperature and pressure are uniform. A negative Delta G indicates that the products have
less free energy than the reactants, making the reaction exergonic. Such reactions occur
spontaneously because they release energy into their surroundings.
3. How do enzymes speed up chemical reactions in a cell?
A. By increasing the temperature of the reaction environment
B. By providing the necessary activation energy
C. By changing the Delta G of the reaction
D. By lowering the activation energy barrier
Answer: D
,Rationale: Enzymes act as biological catalysts by stabilizing the transition state of a
substrate. They reduce the amount of activation energy required for a reaction to proceed
at a significant rate. It is important to note that enzymes do not change the total free energy
change (Delta G) of the reaction itself.
4. Which site on an enzyme does a competitive inhibitor bind to?
A. The allosteric site
B. The phosphate binding site
C. The regulatory site
D. The active site
Answer: D
Rationale: Competitive inhibitors structurally resemble the substrate and compete for the
same physical location on the enzyme. By binding to the active site, they block the substrate
from entering and reacting. This type of inhibition can often be overcome by increasing the
concentration of the actual substrate.
5. In cellular respiration, what is the net yield of ATP produced per glucose molecule during
glycolysis?
A. 1 ATP
B. 32 ATP
C. 4 ATP
D. 2 ATP
Answer: D
Rationale: Glycolysis consists of an energy investment phase and an energy payoff phase.
While 4 ATP molecules are produced total, 2 ATP molecules are consumed during the
initial steps. Therefore, the net gain for the cell is exactly 2 ATP molecules per molecule of
glucose processed.
6. What is the primary role of NAD+ in cellular respiration?
A. To act as a final electron acceptor in the ETC
B. To provide energy for the sodium-potassium pump
C. To act as an electron carrier (oxidizing agent)
D. To catalyze the conversion of glucose to pyruvate
Answer: C
Rationale: NAD+ functions as a coenzyme that accepts electrons from organic molecules,
becoming reduced to NADH. It carries these high-energy electrons to the electron transport
, chain where they are used to drive ATP synthesis. Without NAD+, the redox reactions of
glycolysis and the citric acid cycle would cease to function.
7. Where does the Citric Acid Cycle (Krebs Cycle) occur in eukaryotic cells?
A. Cytosol
B. Inner mitochondrial membrane
C. Mitochondrial matrix
D. Intermembrane space
Answer: C
Rationale: After pyruvate is transported into the mitochondria and converted to Acetyl-
CoA, it enters the citric acid cycle. This series of reactions takes place within the
mitochondrial matrix, the innermost compartment. The matrix contains all the necessary
enzymes and substrates to facilitate the oxidation of carbon compounds.
8. During the electron transport chain, what is the direct source of energy that powers ATP
synthase?
A. The hydrolysis of ATP
B. Electrons flowing through the chain
C. A proton (H+) gradient across the inner membrane
D. The oxidation of NADH to NAD+
Answer: C
Rationale: The movement of electrons through the transport chain pumps protons from
the matrix into the intermembrane space. This creates an electrochemical gradient, known
as the proton-motive force. As protons flow back into the matrix through ATP synthase, the
kinetic energy of their movement is used to phosphorylate ADP into ATP.
9. What is the final electron acceptor in aerobic cellular respiration?
A. Oxygen
B. Carbon dioxide
C. Water
D. Pyruvate
Answer: A
Rationale: In aerobic organisms, molecular oxygen (O2) serves as the ultimate destination
for electrons traveling down the transport chain. Oxygen has a high electronegativity,
allowing it to pull electrons through the various complexes. When oxygen accepts these
electrons along with protons, it is reduced to form water.
