BIO111 Exam 2 Actual Exam V3 | BIO111 General Biology (BIO111
Exam 2) | UCLA
1. According to the first law of thermodynamics, which of the following is true?
A. Energy can be created but not destroyed.
B. The entropy of the universe is constantly decreasing.
C. Energy can be transferred and transformed, but it cannot be created or destroyed.
D. Systems naturally move toward a state of higher order.
Answer: C
Rationale: The first law of thermodynamics is also known as the principle of conservation
of energy. It states that energy in the universe is constant and cannot be produced from
nothing. This means that biological systems must acquire energy from their surroundings
rather than creating it themselves.
2. Which of the following describes an exergonic reaction?
A. A reaction that absorbs free energy from its surroundings.
B. A reaction with a positive Delta G value.
C. A reaction that proceeds with a net release of free energy.
D. A non-spontaneous reaction that requires energy input.
Answer: C
Rationale: Exergonic reactions are characterized by a negative change in free energy,
meaning the products have less energy than the reactants. Because these reactions release
energy, they occur spontaneously under the right conditions. This release of energy is often
coupled to endergonic processes in the cell to perform work.
3. How do enzymes increase the rate of chemical reactions?
A. By increasing the Delta G of the reaction.
B. By providing the activation energy required for the reaction.
C. By changing the equilibrium constant of the reaction.
D. By lowering the activation energy barrier.
Answer: D
Rationale: Enzymes act as biological catalysts that speed up metabolic reactions by
lowering the energy of activation. They do not change the total free energy released or
,absorbed by the reaction itself. Instead, they stabilize the transition state, making it easier
for reactants to reach the state where bonds can break and reform.
4. A competitive inhibitor decreases the rate of an enzyme reaction by:
A. Changing the shape of the enzyme’s active site.
B. Binding to an allosteric site to induce a conformational change.
C. Binding to the active site and blocking substrate access.
D. Irreversibly denaturing the enzyme protein.
Answer: C
Rationale: Competitive inhibitors are molecules that structurally resemble the substrate
and compete for the same active site on the enzyme. If the concentration of the substrate is
increased sufficiently, the effect of the competitive inhibitor can be overcome. This
distinguishes it from non-competitive inhibition, where the inhibitor binds elsewhere on
the enzyme.
5. What is the primary function of ATP in cellular metabolism?
A. To serve as a long-term energy storage molecule like fat.
B. To store genetic information for protein synthesis.
C. To act as a structural component of the cell wall.
D. To provide energy for endergonic reactions through phosphorylation.
Answer: D
Rationale: ATP serves as the immediate energy currency of the cell, providing the
necessary power for cellular work. It functions by transferring a phosphate group to
another molecule, a process known as phosphorylation, which makes the recipient
molecule more reactive. This coupling allows the cell to use the energy from exergonic ATP
hydrolysis to drive endergonic processes.
6. During glycolysis, for each molecule of glucose oxidized to pyruvate, what is the net gain of
ATP?
A. 4 ATP
B. 2 ATP
C. 32 ATP
D. 0 ATP
Answer: B
Rationale: Glycolysis involves an initial energy investment phase where 2 ATP are
consumed to prime the glucose molecule. Subsequently, 4 ATP are produced during the
, energy payoff phase via substrate-level phosphorylation. Therefore, the net gain for the cell
is 2 ATP molecules per glucose processed.
7. Where does the Citric Acid (Krebs) Cycle take place in eukaryotic cells?
A. Cytosol
B. Intermembrane space
C. Inner mitochondrial membrane
D. Mitochondrial matrix
Answer: D
Rationale: The Citric Acid Cycle occurs within the mitochondrial matrix, where the
necessary enzymes are located. This follows the transport of pyruvate into the
mitochondria and its conversion into Acetyl-CoA. The products of this cycle, such as NADH
and FADH2, then move to the inner membrane for the electron transport chain.
8. Which molecule is the final electron acceptor at the end of the electron transport chain in
aerobic respiration?
A. Water
B. Carbon dioxide
C. NAD+
D. Oxygen
Answer: D
Rationale: In aerobic respiration, oxygen serves as the terminal electron acceptor because
of its high electronegativity. As electrons reach the end of the transport chain, they
combine with oxygen and hydrogen ions to form water. Without oxygen, the electron
transport chain would back up, and ATP production would cease.
9. What is the purpose of the proton gradient established during oxidative phosphorylation?
A. To lower the pH of the mitochondrial matrix.
B. To reduce NAD+ back to NADH.
C. To provide the energy for ATP synthesis via ATP synthase.
D. To pump pyruvate into the mitochondria.
Answer: C
Rationale: The electron transport chain pumps hydrogen ions across the inner membrane,
creating a high concentration of protons in the intermembrane space. This electrochemical
gradient represents potential energy, often called the proton-motive force. As protons flow
Exam 2) | UCLA
1. According to the first law of thermodynamics, which of the following is true?
A. Energy can be created but not destroyed.
B. The entropy of the universe is constantly decreasing.
C. Energy can be transferred and transformed, but it cannot be created or destroyed.
D. Systems naturally move toward a state of higher order.
Answer: C
Rationale: The first law of thermodynamics is also known as the principle of conservation
of energy. It states that energy in the universe is constant and cannot be produced from
nothing. This means that biological systems must acquire energy from their surroundings
rather than creating it themselves.
2. Which of the following describes an exergonic reaction?
A. A reaction that absorbs free energy from its surroundings.
B. A reaction with a positive Delta G value.
C. A reaction that proceeds with a net release of free energy.
D. A non-spontaneous reaction that requires energy input.
Answer: C
Rationale: Exergonic reactions are characterized by a negative change in free energy,
meaning the products have less energy than the reactants. Because these reactions release
energy, they occur spontaneously under the right conditions. This release of energy is often
coupled to endergonic processes in the cell to perform work.
3. How do enzymes increase the rate of chemical reactions?
A. By increasing the Delta G of the reaction.
B. By providing the activation energy required for the reaction.
C. By changing the equilibrium constant of the reaction.
D. By lowering the activation energy barrier.
Answer: D
Rationale: Enzymes act as biological catalysts that speed up metabolic reactions by
lowering the energy of activation. They do not change the total free energy released or
,absorbed by the reaction itself. Instead, they stabilize the transition state, making it easier
for reactants to reach the state where bonds can break and reform.
4. A competitive inhibitor decreases the rate of an enzyme reaction by:
A. Changing the shape of the enzyme’s active site.
B. Binding to an allosteric site to induce a conformational change.
C. Binding to the active site and blocking substrate access.
D. Irreversibly denaturing the enzyme protein.
Answer: C
Rationale: Competitive inhibitors are molecules that structurally resemble the substrate
and compete for the same active site on the enzyme. If the concentration of the substrate is
increased sufficiently, the effect of the competitive inhibitor can be overcome. This
distinguishes it from non-competitive inhibition, where the inhibitor binds elsewhere on
the enzyme.
5. What is the primary function of ATP in cellular metabolism?
A. To serve as a long-term energy storage molecule like fat.
B. To store genetic information for protein synthesis.
C. To act as a structural component of the cell wall.
D. To provide energy for endergonic reactions through phosphorylation.
Answer: D
Rationale: ATP serves as the immediate energy currency of the cell, providing the
necessary power for cellular work. It functions by transferring a phosphate group to
another molecule, a process known as phosphorylation, which makes the recipient
molecule more reactive. This coupling allows the cell to use the energy from exergonic ATP
hydrolysis to drive endergonic processes.
6. During glycolysis, for each molecule of glucose oxidized to pyruvate, what is the net gain of
ATP?
A. 4 ATP
B. 2 ATP
C. 32 ATP
D. 0 ATP
Answer: B
Rationale: Glycolysis involves an initial energy investment phase where 2 ATP are
consumed to prime the glucose molecule. Subsequently, 4 ATP are produced during the
, energy payoff phase via substrate-level phosphorylation. Therefore, the net gain for the cell
is 2 ATP molecules per glucose processed.
7. Where does the Citric Acid (Krebs) Cycle take place in eukaryotic cells?
A. Cytosol
B. Intermembrane space
C. Inner mitochondrial membrane
D. Mitochondrial matrix
Answer: D
Rationale: The Citric Acid Cycle occurs within the mitochondrial matrix, where the
necessary enzymes are located. This follows the transport of pyruvate into the
mitochondria and its conversion into Acetyl-CoA. The products of this cycle, such as NADH
and FADH2, then move to the inner membrane for the electron transport chain.
8. Which molecule is the final electron acceptor at the end of the electron transport chain in
aerobic respiration?
A. Water
B. Carbon dioxide
C. NAD+
D. Oxygen
Answer: D
Rationale: In aerobic respiration, oxygen serves as the terminal electron acceptor because
of its high electronegativity. As electrons reach the end of the transport chain, they
combine with oxygen and hydrogen ions to form water. Without oxygen, the electron
transport chain would back up, and ATP production would cease.
9. What is the purpose of the proton gradient established during oxidative phosphorylation?
A. To lower the pH of the mitochondrial matrix.
B. To reduce NAD+ back to NADH.
C. To provide the energy for ATP synthesis via ATP synthase.
D. To pump pyruvate into the mitochondria.
Answer: C
Rationale: The electron transport chain pumps hydrogen ions across the inner membrane,
creating a high concentration of protons in the intermembrane space. This electrochemical
gradient represents potential energy, often called the proton-motive force. As protons flow
