PORTAGE LEARNING BIOL 271
MICROBIOLOGY MODULE 3 EXAM
1. Which of the following best describes metabolism within a microbial cell?
A. The process of breaking down complex molecules into simpler ones only.
B. The sum of all chemical reactions including those that release and require energy.
C. The synthesis of macromolecules from smaller precursors to store energy.
D. The movement of electrons through the plasma membrane to generate heat.
Answer: B
Conceptual Explanation: Metabolism encompasses both catabolism (breaking down) and
anabolism (building up) within the cell.
2. An enzyme functions by lowering which of the following parameters?
A. The free energy change (delta G) of the reaction.
B. The temperature of the environment.
C. The activation energy required for the reaction to proceed.
D. The concentration of products formed at equilibrium.
,Answer: C
Conceptual Explanation: Enzymes act as biological catalysts that lower the activation
energy barrier, allowing reactions to occur faster.
3. What is the non-protein component of an enzyme that is required for its activity called?
A. Cofactor
B. Apoenzyme
C. Holoenzyme
D. Substrate
Answer: A
Conceptual Explanation: A cofactor is the non-protein helper molecule; the apoenzyme is
the protein part, and together they form the holoenzyme.
4. In competitive inhibition, where does the inhibitor bind on the enzyme?
A. The active site
B. The cofactor binding site
C. The allosteric site
D. The enzyme-substrate complex
Answer: A
, Conceptual Explanation: Competitive inhibitors mimic the substrate and compete directly
for the active site.
5. Which molecule is often referred to as the ‘energy currency’ of the cell?
A. Glucose
B. NADH
C. ATP
D. Pyruvate
Answer: C
Conceptual Explanation: ATP (Adenosine Triphosphate) stores and transfers energy for
cell functions.
6. Which process results in the phosphorylation of ADP using energy from a proton gradient?
A. Oxidative phosphorylation
B. Substrate-level phosphorylation
C. Fermentation
D. Glycolysis
Answer: A
Conceptual Explanation: Oxidative phosphorylation uses the electron transport chain to
create a proton gradient that drives ATP synthase.
MICROBIOLOGY MODULE 3 EXAM
1. Which of the following best describes metabolism within a microbial cell?
A. The process of breaking down complex molecules into simpler ones only.
B. The sum of all chemical reactions including those that release and require energy.
C. The synthesis of macromolecules from smaller precursors to store energy.
D. The movement of electrons through the plasma membrane to generate heat.
Answer: B
Conceptual Explanation: Metabolism encompasses both catabolism (breaking down) and
anabolism (building up) within the cell.
2. An enzyme functions by lowering which of the following parameters?
A. The free energy change (delta G) of the reaction.
B. The temperature of the environment.
C. The activation energy required for the reaction to proceed.
D. The concentration of products formed at equilibrium.
,Answer: C
Conceptual Explanation: Enzymes act as biological catalysts that lower the activation
energy barrier, allowing reactions to occur faster.
3. What is the non-protein component of an enzyme that is required for its activity called?
A. Cofactor
B. Apoenzyme
C. Holoenzyme
D. Substrate
Answer: A
Conceptual Explanation: A cofactor is the non-protein helper molecule; the apoenzyme is
the protein part, and together they form the holoenzyme.
4. In competitive inhibition, where does the inhibitor bind on the enzyme?
A. The active site
B. The cofactor binding site
C. The allosteric site
D. The enzyme-substrate complex
Answer: A
, Conceptual Explanation: Competitive inhibitors mimic the substrate and compete directly
for the active site.
5. Which molecule is often referred to as the ‘energy currency’ of the cell?
A. Glucose
B. NADH
C. ATP
D. Pyruvate
Answer: C
Conceptual Explanation: ATP (Adenosine Triphosphate) stores and transfers energy for
cell functions.
6. Which process results in the phosphorylation of ADP using energy from a proton gradient?
A. Oxidative phosphorylation
B. Substrate-level phosphorylation
C. Fermentation
D. Glycolysis
Answer: A
Conceptual Explanation: Oxidative phosphorylation uses the electron transport chain to
create a proton gradient that drives ATP synthase.
