BIO 250 Exam 2 V1 | BIO 250 Microbiology
| Actual Q&A with Rationale (BIO250 Exam
2) | StraighterLine
1. Which of the following describes the protein portion of a holoenzyme?
A. Cofactor
B. Coenzyme
C. Apoenzyme
D. Prosthetic group
Answer: C
Rationale: The apoenzyme is the protein component of a conjugated enzyme, also known
as a holoenzyme. It requires a specific cofactor or coenzyme to become catalytically active.
Once the cofactor is bound to the apoenzyme, the resulting complex is termed the
holoenzyme, which is capable of performing its biochemical function.
2. Metabolic pathways that release energy by breaking down complex molecules into simpler
compounds are known as:
A. Anabolic pathways
B. Fermentative pathways
C. Amphibolic pathways
D. Catabolic pathways
,Answer: D
Rationale: Catabolism involves the degradative phase of metabolism in which larger
molecules like glucose are broken down. These processes are exergonic, meaning they
release energy that the cell can then use for work. In contrast, anabolism refers to the
synthesis of complex molecules from simpler ones, requiring an input of energy.
3. Which of the following characteristics apply to the process of glycolysis? (Select All That
Apply)
A. It occurs in the cytoplasm of both prokaryotes and eukaryotes.
B. It results in the net production of 2 ATP per glucose molecule.
C. It requires the presence of oxygen to proceed.
D. It produces two molecules of NADH.
E. It takes place within the mitochondrial matrix.
F. It converts one glucose molecule into two molecules of pyruvate.
Answer: A, B, D, F
Rationale: Glycolysis is a universal metabolic pathway that does not require oxygen,
allowing it to function under both aerobic and anaerobic conditions. It yields a net gain of
two ATP through substrate-level phosphorylation and two NADH molecules through
oxidation. The final organic product of this pathway is pyruvate, which can then enter
further metabolic cycles depending on the organism’s respiratory capacity.
, 4. During the Krebs cycle (Citric Acid Cycle), which molecule is the first to form after the
combination of Acetyl-CoA and Oxaloacetate?
A. Pyruvate
B. Citrate
C. Alpha-ketoglutarate
D. Isocitrate
Answer: B
Rationale: The Krebs cycle begins when the two-carbon Acetyl-CoA combines with the
four-carbon oxaloacetate. This condensation reaction is catalyzed by citrate synthase and
results in the formation of citrate, a six-carbon molecule. This step is significant because it
initiates the cyclic sequence of reactions that regenerate oxaloacetate while producing CO2
and energy carriers.
5. Where is the electron transport chain (ETC) located in a prokaryotic cell?
A. Mitochondrial inner membrane
B. Cytoplasm
C. Periplasmic space
D. Cell membrane
Answer: D
| Actual Q&A with Rationale (BIO250 Exam
2) | StraighterLine
1. Which of the following describes the protein portion of a holoenzyme?
A. Cofactor
B. Coenzyme
C. Apoenzyme
D. Prosthetic group
Answer: C
Rationale: The apoenzyme is the protein component of a conjugated enzyme, also known
as a holoenzyme. It requires a specific cofactor or coenzyme to become catalytically active.
Once the cofactor is bound to the apoenzyme, the resulting complex is termed the
holoenzyme, which is capable of performing its biochemical function.
2. Metabolic pathways that release energy by breaking down complex molecules into simpler
compounds are known as:
A. Anabolic pathways
B. Fermentative pathways
C. Amphibolic pathways
D. Catabolic pathways
,Answer: D
Rationale: Catabolism involves the degradative phase of metabolism in which larger
molecules like glucose are broken down. These processes are exergonic, meaning they
release energy that the cell can then use for work. In contrast, anabolism refers to the
synthesis of complex molecules from simpler ones, requiring an input of energy.
3. Which of the following characteristics apply to the process of glycolysis? (Select All That
Apply)
A. It occurs in the cytoplasm of both prokaryotes and eukaryotes.
B. It results in the net production of 2 ATP per glucose molecule.
C. It requires the presence of oxygen to proceed.
D. It produces two molecules of NADH.
E. It takes place within the mitochondrial matrix.
F. It converts one glucose molecule into two molecules of pyruvate.
Answer: A, B, D, F
Rationale: Glycolysis is a universal metabolic pathway that does not require oxygen,
allowing it to function under both aerobic and anaerobic conditions. It yields a net gain of
two ATP through substrate-level phosphorylation and two NADH molecules through
oxidation. The final organic product of this pathway is pyruvate, which can then enter
further metabolic cycles depending on the organism’s respiratory capacity.
, 4. During the Krebs cycle (Citric Acid Cycle), which molecule is the first to form after the
combination of Acetyl-CoA and Oxaloacetate?
A. Pyruvate
B. Citrate
C. Alpha-ketoglutarate
D. Isocitrate
Answer: B
Rationale: The Krebs cycle begins when the two-carbon Acetyl-CoA combines with the
four-carbon oxaloacetate. This condensation reaction is catalyzed by citrate synthase and
results in the formation of citrate, a six-carbon molecule. This step is significant because it
initiates the cyclic sequence of reactions that regenerate oxaloacetate while producing CO2
and energy carriers.
5. Where is the electron transport chain (ETC) located in a prokaryotic cell?
A. Mitochondrial inner membrane
B. Cytoplasm
C. Periplasmic space
D. Cell membrane
Answer: D
