BIOD 171 MICROBIOLOGY MODULE 6 EXAM –
PORTAGE LEARNING ACTUAL EXAM QUESTIONS
AND CORRECT ANSWERS WITH RATIONALES
GRADED A+ LATEST
Question 1
Which characteristic best distinguishes an enzyme from a non-biological catalyst?
A. It increases reaction temperature
B. It is consumed during the reaction
C. It exhibits substrate specificity
D. It functions only at neutral pH
Correct Answer: C
Rationale: Enzymes are highly specific, binding only particular substrates due to
their unique active sites. They are not consumed and can function across various
pH ranges depending on the enzyme.
Question 2
A competitive inhibitor reduces enzyme activity by:
A. Binding to an allosteric site
B. Permanently altering enzyme structure
C. Competing with the substrate for the active site
D. Lowering the activation energy
Correct Answer: C
Rationale: Competitive inhibitors resemble the substrate and compete for binding
at the enzyme’s active site, reducing enzyme–substrate complex formation.
,Question 3
Which metabolic pathway generates the greatest amount of ATP per glucose
molecule under aerobic conditions?
A. Glycolysis
B. Pentose phosphate pathway
C. Krebs cycle
D. Electron transport chain
Correct Answer: D
Rationale: While glycolysis and the Krebs cycle produce some ATP directly, the
majority of ATP is generated through oxidative phosphorylation in the electron
transport chain.
Question 4
During glycolysis, glucose is converted into:
A. Acetyl-CoA
B. Two molecules of pyruvate
C. Carbon dioxide and water
D. Lactate
Correct Answer: B
Rationale: Glycolysis splits one glucose molecule into two pyruvate molecules,
producing ATP and NADH in the process.
,Question 5
Which molecule acts as the final electron acceptor in aerobic respiration?
A. Carbon dioxide
B. Oxygen
C. NAD⁺
D. Pyruvate
Correct Answer: B
Rationale: Oxygen serves as the terminal electron acceptor in the electron
transport chain, forming water.
Question 6
Fermentation primarily functions to:
A. Generate large amounts of ATP
B. Produce carbon dioxide
C. Regenerate NAD⁺
D. Oxidize glucose completely
Correct Answer: C
Rationale: Fermentation allows cells to regenerate NAD⁺ from NADH so
glycolysis can continue in the absence of oxygen.
Question 7
Which organism classification requires organic carbon and light energy?
A. Chemoautotroph
B. Photoautotroph
C. Photoheterotroph
D. Chemoheterotroph
Correct Answer: C
Rationale: Photoheterotrophs use light as an energy source but rely on organic
compounds for carbon.
, Question 8
Anabolism is best described as metabolism that:
A. Breaks down complex molecules
B. Releases energy
C. Builds complex molecules
D. Occurs only in mitochondria
Correct Answer: C
Rationale: Anabolic reactions synthesize complex molecules from simpler ones
and typically require energy input.
Question 9
Which factor would most likely denature a bacterial enzyme?
A. Slight substrate increase
B. Minor temperature change
C. Extreme pH shift
D. Increased enzyme concentration
Correct Answer: C
Rationale: Extreme pH alters protein structure, disrupting hydrogen bonds and
denaturing enzymes.
Question 10
The lag phase of bacterial growth is characterized by:
A. Rapid cell division
B. Declining cell numbers
C. Cellular adaptation and enzyme synthesis
D. Maximum metabolic activity
Correct Answer: C
Rationale: During lag phase, bacteria adjust to the environment and synthesize
enzymes necessary for growth.
PORTAGE LEARNING ACTUAL EXAM QUESTIONS
AND CORRECT ANSWERS WITH RATIONALES
GRADED A+ LATEST
Question 1
Which characteristic best distinguishes an enzyme from a non-biological catalyst?
A. It increases reaction temperature
B. It is consumed during the reaction
C. It exhibits substrate specificity
D. It functions only at neutral pH
Correct Answer: C
Rationale: Enzymes are highly specific, binding only particular substrates due to
their unique active sites. They are not consumed and can function across various
pH ranges depending on the enzyme.
Question 2
A competitive inhibitor reduces enzyme activity by:
A. Binding to an allosteric site
B. Permanently altering enzyme structure
C. Competing with the substrate for the active site
D. Lowering the activation energy
Correct Answer: C
Rationale: Competitive inhibitors resemble the substrate and compete for binding
at the enzyme’s active site, reducing enzyme–substrate complex formation.
,Question 3
Which metabolic pathway generates the greatest amount of ATP per glucose
molecule under aerobic conditions?
A. Glycolysis
B. Pentose phosphate pathway
C. Krebs cycle
D. Electron transport chain
Correct Answer: D
Rationale: While glycolysis and the Krebs cycle produce some ATP directly, the
majority of ATP is generated through oxidative phosphorylation in the electron
transport chain.
Question 4
During glycolysis, glucose is converted into:
A. Acetyl-CoA
B. Two molecules of pyruvate
C. Carbon dioxide and water
D. Lactate
Correct Answer: B
Rationale: Glycolysis splits one glucose molecule into two pyruvate molecules,
producing ATP and NADH in the process.
,Question 5
Which molecule acts as the final electron acceptor in aerobic respiration?
A. Carbon dioxide
B. Oxygen
C. NAD⁺
D. Pyruvate
Correct Answer: B
Rationale: Oxygen serves as the terminal electron acceptor in the electron
transport chain, forming water.
Question 6
Fermentation primarily functions to:
A. Generate large amounts of ATP
B. Produce carbon dioxide
C. Regenerate NAD⁺
D. Oxidize glucose completely
Correct Answer: C
Rationale: Fermentation allows cells to regenerate NAD⁺ from NADH so
glycolysis can continue in the absence of oxygen.
Question 7
Which organism classification requires organic carbon and light energy?
A. Chemoautotroph
B. Photoautotroph
C. Photoheterotroph
D. Chemoheterotroph
Correct Answer: C
Rationale: Photoheterotrophs use light as an energy source but rely on organic
compounds for carbon.
, Question 8
Anabolism is best described as metabolism that:
A. Breaks down complex molecules
B. Releases energy
C. Builds complex molecules
D. Occurs only in mitochondria
Correct Answer: C
Rationale: Anabolic reactions synthesize complex molecules from simpler ones
and typically require energy input.
Question 9
Which factor would most likely denature a bacterial enzyme?
A. Slight substrate increase
B. Minor temperature change
C. Extreme pH shift
D. Increased enzyme concentration
Correct Answer: C
Rationale: Extreme pH alters protein structure, disrupting hydrogen bonds and
denaturing enzymes.
Question 10
The lag phase of bacterial growth is characterized by:
A. Rapid cell division
B. Declining cell numbers
C. Cellular adaptation and enzyme synthesis
D. Maximum metabolic activity
Correct Answer: C
Rationale: During lag phase, bacteria adjust to the environment and synthesize
enzymes necessary for growth.
