BIOD 171 — Essential Microbiology: Module 2 Exam 2026/2027
UPDATE
1. Which of the following describes metabolism?
A. The study of microscopic organisms
B. The physical structure of a cell wall
C. The process of genetic replication
D. The sum of all chemical reactions within a living organism
Answer: D
Rationale: Metabolism is defined as the total of all chemical reactions that occur within an
organism, including both energy-releasing and energy-consuming processes.
2. What is the primary function of enzymes in biological systems?
A. To provide structural support to the cell
B. To act as the genetic blueprint
C. To store energy in the form of lipids
D. To speed up chemical reactions by lowering activation energy
Answer: D
Rationale: Enzymes are biological catalysts that increase the rate of chemical reactions by
lowering the activation energy required for the reaction to proceed.
,3. In which type of metabolic reaction are complex molecules broken down into
simpler ones with the release of energy?
A. Anabolic
B. Isomeric
C. Photosynthetic
D. Catabolic
Answer: D
Rationale: Catabolism refers to the breakdown of complex organic compounds into
simpler ones, which generally releases energy.
4. The energy currency of the cell is known as:
A. DNA
B. Glucose
C. ATP
D. NADH
Answer: C
Rationale: Adenosine Triphosphate (ATP) is the principal energy-carrying molecule used
by all cells to perform work.
5. An enzyme’s specificity is determined by the shape of its:
A. Cofactor
B. Apoenzyme
C. Active site
D. Product
Answer: C
Rationale: The active site is the specific region of an enzyme where the substrate binds
and the reaction occurs; its unique shape determines specificity.
, 6. Which of the following describes a competitive inhibitor?
A. It binds to the allosteric site
B. It competes with the substrate for the active site
C. It changes the shape of the enzyme permanently
D. It acts as a cofactor for the reaction
Answer: B
Rationale: Competitive inhibitors have a similar shape to the substrate and compete for
binding at the active site, effectively blocking the substrate.
7. What is the net gain of ATP molecules produced during glycolysis?
A. 1
B. 38
C. 4
D. 2
Answer: D
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the early stages, resulting in
a net gain of 2 ATP per glucose molecule.
8. During the intermediate step between glycolysis and the Krebs cycle,
pyruvate is converted into:
A. Lactic acid
B. Citric acid
C. Oxaloacetate
D. Acetyl-CoA
Answer: D
Rationale: Pyruvate must be oxidized and decarboxylated into Acetyl-CoA before it can
enter the Krebs cycle.
UPDATE
1. Which of the following describes metabolism?
A. The study of microscopic organisms
B. The physical structure of a cell wall
C. The process of genetic replication
D. The sum of all chemical reactions within a living organism
Answer: D
Rationale: Metabolism is defined as the total of all chemical reactions that occur within an
organism, including both energy-releasing and energy-consuming processes.
2. What is the primary function of enzymes in biological systems?
A. To provide structural support to the cell
B. To act as the genetic blueprint
C. To store energy in the form of lipids
D. To speed up chemical reactions by lowering activation energy
Answer: D
Rationale: Enzymes are biological catalysts that increase the rate of chemical reactions by
lowering the activation energy required for the reaction to proceed.
,3. In which type of metabolic reaction are complex molecules broken down into
simpler ones with the release of energy?
A. Anabolic
B. Isomeric
C. Photosynthetic
D. Catabolic
Answer: D
Rationale: Catabolism refers to the breakdown of complex organic compounds into
simpler ones, which generally releases energy.
4. The energy currency of the cell is known as:
A. DNA
B. Glucose
C. ATP
D. NADH
Answer: C
Rationale: Adenosine Triphosphate (ATP) is the principal energy-carrying molecule used
by all cells to perform work.
5. An enzyme’s specificity is determined by the shape of its:
A. Cofactor
B. Apoenzyme
C. Active site
D. Product
Answer: C
Rationale: The active site is the specific region of an enzyme where the substrate binds
and the reaction occurs; its unique shape determines specificity.
, 6. Which of the following describes a competitive inhibitor?
A. It binds to the allosteric site
B. It competes with the substrate for the active site
C. It changes the shape of the enzyme permanently
D. It acts as a cofactor for the reaction
Answer: B
Rationale: Competitive inhibitors have a similar shape to the substrate and compete for
binding at the active site, effectively blocking the substrate.
7. What is the net gain of ATP molecules produced during glycolysis?
A. 1
B. 38
C. 4
D. 2
Answer: D
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the early stages, resulting in
a net gain of 2 ATP per glucose molecule.
8. During the intermediate step between glycolysis and the Krebs cycle,
pyruvate is converted into:
A. Lactic acid
B. Citric acid
C. Oxaloacetate
D. Acetyl-CoA
Answer: D
Rationale: Pyruvate must be oxidized and decarboxylated into Acetyl-CoA before it can
enter the Krebs cycle.
