BIO 250 Exam 2 V2 | BIO 250 Microbiology
| Actual Q&A with Rationale (BIO250 Exam
2) | StraighterLine
1. Which of the following are characteristics of enzymes in microbial metabolism? (Select all
that apply)
A. They are consumed during the chemical reaction
B. They lower the activation energy required for a reaction
C. They consist primarily of protein structures
D. They increase the free energy (delta G) of the products
E. They exhibit high specificity for their substrates
F. They function optimally regardless of pH changes
Answer: B, C, E
Rationale: Enzymes serve as biological catalysts that significantly speed up reactions by
lowering the energy barrier. Most enzymes are proteins that fold into specific three-
dimensional shapes to create an active site. This specificity ensures that only particular
substrates can bind and undergo transformation into products.
2. Which molecule is the standard ‘energy currency’ of the cell, providing energy for anabolic
reactions?
A. NAD+
,B. Glucose
C. Adenosine triphosphate (ATP)
D. Pyruvate
Answer: C
Rationale: ATP is the primary molecule used by cells to store and transfer energy for
cellular work. It contains high-energy phosphate bonds that release energy when
hydrolyzed to ADP and inorganic phosphate. This released energy is then used to drive
endergonic metabolic processes.
3. In aerobic respiration, what is the final electron acceptor in the electron transport chain?
A. Nitrate
B. Sulfate
C. Carbon dioxide
D. Oxygen
Answer: D
Rationale: Aerobic respiration is characterized by the use of molecular oxygen as the
ultimate recipient of electrons. As electrons move through the transport chain, they lose
energy which is used to pump protons. Finally, oxygen combines with these electrons and
protons to form water as a byproduct.
, 4. What occurs during the ‘lag phase’ of a bacterial growth curve?
A. Rapid cell division and population doubling
B. The death rate is equal to the reproduction rate
C. Cells are adjusting to their environment and synthesizing enzymes
D. Exhaustion of nutrients leading to cell dormancy
Answer: C
Rationale: The lag phase is the initial period after inoculation where no significant
increase in cell number is observed. During this time, bacteria are metabolically active as
they repair damage or prepare for growth in the new medium. They synthesize the specific
proteins and metabolites required for the upcoming phase of rapid division.
5. An organism that thrives at temperatures between 0°C and 15°C is classified as a:
A. Mesophile
B. Thermophile
C. Hyperthermophile
D. Psychrophile
Answer: D
Rationale: Psychrophiles are extremophilic organisms capable of growth and reproduction
in cold temperatures. Their cellular membranes and enzymes are specifically adapted to
| Actual Q&A with Rationale (BIO250 Exam
2) | StraighterLine
1. Which of the following are characteristics of enzymes in microbial metabolism? (Select all
that apply)
A. They are consumed during the chemical reaction
B. They lower the activation energy required for a reaction
C. They consist primarily of protein structures
D. They increase the free energy (delta G) of the products
E. They exhibit high specificity for their substrates
F. They function optimally regardless of pH changes
Answer: B, C, E
Rationale: Enzymes serve as biological catalysts that significantly speed up reactions by
lowering the energy barrier. Most enzymes are proteins that fold into specific three-
dimensional shapes to create an active site. This specificity ensures that only particular
substrates can bind and undergo transformation into products.
2. Which molecule is the standard ‘energy currency’ of the cell, providing energy for anabolic
reactions?
A. NAD+
,B. Glucose
C. Adenosine triphosphate (ATP)
D. Pyruvate
Answer: C
Rationale: ATP is the primary molecule used by cells to store and transfer energy for
cellular work. It contains high-energy phosphate bonds that release energy when
hydrolyzed to ADP and inorganic phosphate. This released energy is then used to drive
endergonic metabolic processes.
3. In aerobic respiration, what is the final electron acceptor in the electron transport chain?
A. Nitrate
B. Sulfate
C. Carbon dioxide
D. Oxygen
Answer: D
Rationale: Aerobic respiration is characterized by the use of molecular oxygen as the
ultimate recipient of electrons. As electrons move through the transport chain, they lose
energy which is used to pump protons. Finally, oxygen combines with these electrons and
protons to form water as a byproduct.
, 4. What occurs during the ‘lag phase’ of a bacterial growth curve?
A. Rapid cell division and population doubling
B. The death rate is equal to the reproduction rate
C. Cells are adjusting to their environment and synthesizing enzymes
D. Exhaustion of nutrients leading to cell dormancy
Answer: C
Rationale: The lag phase is the initial period after inoculation where no significant
increase in cell number is observed. During this time, bacteria are metabolically active as
they repair damage or prepare for growth in the new medium. They synthesize the specific
proteins and metabolites required for the upcoming phase of rapid division.
5. An organism that thrives at temperatures between 0°C and 15°C is classified as a:
A. Mesophile
B. Thermophile
C. Hyperthermophile
D. Psychrophile
Answer: D
Rationale: Psychrophiles are extremophilic organisms capable of growth and reproduction
in cold temperatures. Their cellular membranes and enzymes are specifically adapted to
