BIO 250 Final Exam V1 | BIO 250 Microbiology |
Actual Q&A with Rationale (BIO250 Final Exam) |
StraighterLine
1. Which of the following serves as the primary stain during the standard Gram stain
procedure?
A. Safranin
B. Iodine
C. Crystal Violet
D. Alcohol
Correct Answer: C
Explanation: Crystal violet is the primary stain in the Gram staining procedure. It binds to
the peptidoglycan layer of the bacterial cell wall. This step is essential for differentiating
between Gram-positive and Gram-negative organisms based on their cell wall composition.
2. Which of the following structures are found in all prokaryotic cells? Select all that apply.
A. Ribosomes
B. Nucleoid
C. Plasma membrane
D. A, B, and C only
E. Capsule
,F. Endospores
Correct Answer: D
Explanation: All prokaryotic cells must possess ribosomes for protein synthesis and a
nucleoid region to house their genetic material. The plasma membrane is also universal as
it regulates the transport of materials in and out of the cell. Endospores and capsules are
specialized structures found only in specific bacterial species.
3. During which phase of the bacterial growth curve do cells divide at their maximum rate?
A. Lag phase
B. Stationary phase
C. Log phase
D. Death phase
Correct Answer: C
Explanation: The log phase, or exponential phase, is characterized by active cell doubling.
During this period, the metabolic activity is highest and generation time is at its minimum.
This is the stage where bacteria are most sensitive to adverse conditions like antibiotics.
4. What is the net gain of ATP molecules produced per molecule of glucose during glycolysis?
A. 4 ATP
B. 2 ATP
C. 36 ATP
, D. 38 ATP
Correct Answer: B
Explanation: Glycolysis consumes 2 ATP molecules in the preparatory phase and produces
4 ATP molecules in the energy-conserving phase. This results in a net gain of 2 ATP per
glucose molecule. Additionally, 2 NADH molecules are produced for use in the electron
transport chain.
5. Which standard temperature and pressure parameters are required for sterilization in a
typical autoclave?
A. 100 degrees Celsius at 10 psi for 10 minutes
B. 160 degrees Celsius at 0 psi for 2 hours
C. 121 degrees Celsius at 20 psi for 30 minutes
D. 121 degrees Celsius at 15 psi for 15 minutes
Correct Answer: D
Explanation: Steam sterilization in an autoclave requires high pressure to raise the boiling
point of water. The standard setting of 121 degrees Celsius at 15 psi is sufficient to kill even
highly resistant bacterial endospores. Increasing the time may be necessary for large loads,
but the temperature and pressure are the standard benchmarks.
6. An apoenzyme combined with its cofactor is referred to as a:
A. Coenzyme
Actual Q&A with Rationale (BIO250 Final Exam) |
StraighterLine
1. Which of the following serves as the primary stain during the standard Gram stain
procedure?
A. Safranin
B. Iodine
C. Crystal Violet
D. Alcohol
Correct Answer: C
Explanation: Crystal violet is the primary stain in the Gram staining procedure. It binds to
the peptidoglycan layer of the bacterial cell wall. This step is essential for differentiating
between Gram-positive and Gram-negative organisms based on their cell wall composition.
2. Which of the following structures are found in all prokaryotic cells? Select all that apply.
A. Ribosomes
B. Nucleoid
C. Plasma membrane
D. A, B, and C only
E. Capsule
,F. Endospores
Correct Answer: D
Explanation: All prokaryotic cells must possess ribosomes for protein synthesis and a
nucleoid region to house their genetic material. The plasma membrane is also universal as
it regulates the transport of materials in and out of the cell. Endospores and capsules are
specialized structures found only in specific bacterial species.
3. During which phase of the bacterial growth curve do cells divide at their maximum rate?
A. Lag phase
B. Stationary phase
C. Log phase
D. Death phase
Correct Answer: C
Explanation: The log phase, or exponential phase, is characterized by active cell doubling.
During this period, the metabolic activity is highest and generation time is at its minimum.
This is the stage where bacteria are most sensitive to adverse conditions like antibiotics.
4. What is the net gain of ATP molecules produced per molecule of glucose during glycolysis?
A. 4 ATP
B. 2 ATP
C. 36 ATP
, D. 38 ATP
Correct Answer: B
Explanation: Glycolysis consumes 2 ATP molecules in the preparatory phase and produces
4 ATP molecules in the energy-conserving phase. This results in a net gain of 2 ATP per
glucose molecule. Additionally, 2 NADH molecules are produced for use in the electron
transport chain.
5. Which standard temperature and pressure parameters are required for sterilization in a
typical autoclave?
A. 100 degrees Celsius at 10 psi for 10 minutes
B. 160 degrees Celsius at 0 psi for 2 hours
C. 121 degrees Celsius at 20 psi for 30 minutes
D. 121 degrees Celsius at 15 psi for 15 minutes
Correct Answer: D
Explanation: Steam sterilization in an autoclave requires high pressure to raise the boiling
point of water. The standard setting of 121 degrees Celsius at 15 psi is sufficient to kill even
highly resistant bacterial endospores. Increasing the time may be necessary for large loads,
but the temperature and pressure are the standard benchmarks.
6. An apoenzyme combined with its cofactor is referred to as a:
A. Coenzyme
