BIO 250 Exam 3 V2 | BIO 250 Microbiology | Actual
Q&A with Rationale (BIO250 Exam 3) |
StraighterLine
1. Which of the following best describes the function of an apoenzyme?
A. The complete, active form of an enzyme including its cofactors.
B. A non-protein molecule that assists in catalytic activity.
C. The protein portion of an enzyme that is inactive without a specific cofactor.
D. An organic molecule that binds to the active site permanently.
Correct Answer: C
Explanation: An apoenzyme is specifically the proteinaceous part of an enzyme that
requires a cofactor to become a functional holoenzyme. Without the binding of its
necessary inorganic ion or organic coenzyme, the apoenzyme remains catalytically inactive.
This structural distinction is vital for understanding how metabolic pathways are regulated
via cofactor availability.
2. During aerobic respiration, which process yields the highest number of ATP molecules via
oxidative phosphorylation?
A. Glycolysis
B. The Electron Transport Chain
C. The Intermediate Step (Transition reaction)
,D. The Krebs Cycle
Correct Answer: B
Explanation: The Electron Transport Chain (ETC) utilizes the reduced coenzymes NADH
and FADH2 to generate a proton motive force. Through the process of chemiosmosis, ATP
synthase produces approximately 32-34 ATP per glucose molecule. In contrast, glycolysis
and the Krebs cycle only produce a small amount of ATP through substrate-level
phosphorylation.
3. In DNA replication, which enzyme is responsible for synthesizing a short RNA sequence to
provide a starting point for DNA Polymerase III?
A. Primase
B. Helicase
C. DNA Ligase
D. Gyrase
Correct Answer: A
Explanation: Primase is a type of RNA polymerase that creates a RNA primer, which is
essential because DNA polymerase III can only add nucleotides to an existing 3’ OH group.
Once the primer is in place, DNA replication can proceed on both the leading and lagging
strands. These RNA primers are eventually removed and replaced with DNA by DNA
Polymerase I.
, 4. Which of the following factors are known to influence the effectiveness of a chemical
antimicrobial agent? (Select all that apply)
A. The concentration of the chemical agent.
B. The presence of organic matter such as blood or biofilms.
C. The temperature and pH of the environment.
D. The population size and type of microorganisms present.
E. All of the above factors influence effectiveness.
F. The length of time the microbes are exposed to the agent.
Correct Answer: E
Explanation: Antimicrobial efficacy is not determined by a single factor but by a complex
interaction of environmental and biological variables. For instance, organic debris can
shield bacteria or neutralize chemicals, while higher temperatures often enhance the
reaction rate of disinfectants. Understanding these variables is critical for ensuring proper
sterilization and disinfection protocols in clinical settings.
5. What is the primary role of the Krebs cycle (Citric Acid Cycle) in microbial metabolism?
A. To produce large amounts of ATP through substrate-level phosphorylation only.
B. To regenerate NAD+ for glycolysis in the absence of oxygen.
C. To oxidize acetyl-CoA and reduce coenzymes NADH and FADH2 for the electron
transport chain.
Q&A with Rationale (BIO250 Exam 3) |
StraighterLine
1. Which of the following best describes the function of an apoenzyme?
A. The complete, active form of an enzyme including its cofactors.
B. A non-protein molecule that assists in catalytic activity.
C. The protein portion of an enzyme that is inactive without a specific cofactor.
D. An organic molecule that binds to the active site permanently.
Correct Answer: C
Explanation: An apoenzyme is specifically the proteinaceous part of an enzyme that
requires a cofactor to become a functional holoenzyme. Without the binding of its
necessary inorganic ion or organic coenzyme, the apoenzyme remains catalytically inactive.
This structural distinction is vital for understanding how metabolic pathways are regulated
via cofactor availability.
2. During aerobic respiration, which process yields the highest number of ATP molecules via
oxidative phosphorylation?
A. Glycolysis
B. The Electron Transport Chain
C. The Intermediate Step (Transition reaction)
,D. The Krebs Cycle
Correct Answer: B
Explanation: The Electron Transport Chain (ETC) utilizes the reduced coenzymes NADH
and FADH2 to generate a proton motive force. Through the process of chemiosmosis, ATP
synthase produces approximately 32-34 ATP per glucose molecule. In contrast, glycolysis
and the Krebs cycle only produce a small amount of ATP through substrate-level
phosphorylation.
3. In DNA replication, which enzyme is responsible for synthesizing a short RNA sequence to
provide a starting point for DNA Polymerase III?
A. Primase
B. Helicase
C. DNA Ligase
D. Gyrase
Correct Answer: A
Explanation: Primase is a type of RNA polymerase that creates a RNA primer, which is
essential because DNA polymerase III can only add nucleotides to an existing 3’ OH group.
Once the primer is in place, DNA replication can proceed on both the leading and lagging
strands. These RNA primers are eventually removed and replaced with DNA by DNA
Polymerase I.
, 4. Which of the following factors are known to influence the effectiveness of a chemical
antimicrobial agent? (Select all that apply)
A. The concentration of the chemical agent.
B. The presence of organic matter such as blood or biofilms.
C. The temperature and pH of the environment.
D. The population size and type of microorganisms present.
E. All of the above factors influence effectiveness.
F. The length of time the microbes are exposed to the agent.
Correct Answer: E
Explanation: Antimicrobial efficacy is not determined by a single factor but by a complex
interaction of environmental and biological variables. For instance, organic debris can
shield bacteria or neutralize chemicals, while higher temperatures often enhance the
reaction rate of disinfectants. Understanding these variables is critical for ensuring proper
sterilization and disinfection protocols in clinical settings.
5. What is the primary role of the Krebs cycle (Citric Acid Cycle) in microbial metabolism?
A. To produce large amounts of ATP through substrate-level phosphorylation only.
B. To regenerate NAD+ for glycolysis in the absence of oxygen.
C. To oxidize acetyl-CoA and reduce coenzymes NADH and FADH2 for the electron
transport chain.
