BIOC 384 Exam 4 Questions & Answers 2026 | High-Yield
Review | Graded A+
1. Describe the impact of arsenite on the function of lipoamide coenzymes in
the pyruvate dehydrogenase reaction.
Arsenite enhances the activity of lipoamide coenzymes, increasing
reaction efficiency.
Arsenite inhibits the function of lipoamide coenzymes, disrupting
the pyruvate dehydrogenase reaction.
Arsenite has no effect on lipoamide coenzymes.
Arsenite converts lipoamide coenzymes into active forms.
2. If a patient is exposed to arsenic, which metabolic pathway would likely be
disrupted due to the inhibition of lipoamide?
The electron transport chain
The glycolysis pathway
The pyruvate dehydrogenase complex pathway
The citric acid cycle
3. The pyruvate dehydrogenase complex produces , and as products
of its reaction.
Thiamine pyrophosphate; NADH; CO2
FADH2; reduced lipoic acid; acetyl-CoA
Acetyl-CoA; NADH; CO2
Lactate; NADH; acteyl-CoA
,4. Which citrate cycle intermediate is known to be involved in the synthesis of
heme?
Citrate
Alpha-ketoglutarate
Isocitrate
Succinyl-CoA
5. Which statement regarding the Pyruvate Dehydrogenase reaction is correct?
Coenzyme A is irrevesibly metabolized, yielding NADH and acetyl
CoA.
Pyruvate is reduced to NADH and acetyl CoA.
Pyruvate undergoes oxidative decarboxylation, yielding NADH,
carbon dioxide and acetyl CoA.
The six carbon skeletons from the glycolytic intermediate pyruvate
are released as carbon dioxide.
Pyruvate is metabolized to lactic acid, yielding NADH.
6. Describe the significance of the reaction NADH + O2 --> H2O + NAD+ in the
context of cellular respiration.
This reaction shows that oxygen is reduced to form NADH, which is
used in the citric acid cycle.
This reaction is crucial as it represents the transfer of electrons from
NADH to oxygen, leading to the production of water and the
regeneration of NAD+, which is essential for glycolysis and the citric
acid cycle.
This reaction demonstrates the breakdown of glucose into pyruvate.
, This reaction indicates that NADH is converted into FADH2, which is
used in the electron transport chain.
7. Which of the following cofactors of pyruvate dehydrogenase is the target of
arsenic acid and mercury poisoning?
NAD+
FAD
Thiamine pyrophosphate
Lipoic acid
8. What is the typical membrane potential measured in millivolts (mV) for proton
transport across the mitochondrial inner membrane?
200 mV
180 mV
120 mV
160 mV
9. Which electron carrier in the electron transport chain is known to be soluble
and not attached to the inner mitochondrial membrane?
complex II
coenzyme Q
complex I
cytochrome c
10. If a drug inhibits the enzyme responsible for the conversion of pyruvate to
acetyl-CoA, what metabolic consequence might occur?
Increased glycolysis
, Increased lactate production
Enhanced ATP synthesis
Reduced production of acetyl-CoA
11. Citrate is transported out of the mitochondria into the cytosol for use in the
biosynthesis of:
amino acids
insulin
fatty acids
glucose
cholesterol
12. Describe how chloroplasts and mitochondria utilize the proton gradient in
ATP synthesis.
Chloroplasts and mitochondria use the energy from the proton
gradient to drive ATP synthesis through ATP synthase.
Chloroplasts and mitochondria convert the proton gradient into
glucose.
Chloroplasts and mitochondria use the proton gradient to transport
NADH.
Chloroplasts and mitochondria rely on the proton gradient for DNA
replication.
13. In your group: A comparison of mitochondria and chloroplasts shows that
they have very different electron transport protein complexes.
only mitochondria contain ATP synthase.
Review | Graded A+
1. Describe the impact of arsenite on the function of lipoamide coenzymes in
the pyruvate dehydrogenase reaction.
Arsenite enhances the activity of lipoamide coenzymes, increasing
reaction efficiency.
Arsenite inhibits the function of lipoamide coenzymes, disrupting
the pyruvate dehydrogenase reaction.
Arsenite has no effect on lipoamide coenzymes.
Arsenite converts lipoamide coenzymes into active forms.
2. If a patient is exposed to arsenic, which metabolic pathway would likely be
disrupted due to the inhibition of lipoamide?
The electron transport chain
The glycolysis pathway
The pyruvate dehydrogenase complex pathway
The citric acid cycle
3. The pyruvate dehydrogenase complex produces , and as products
of its reaction.
Thiamine pyrophosphate; NADH; CO2
FADH2; reduced lipoic acid; acetyl-CoA
Acetyl-CoA; NADH; CO2
Lactate; NADH; acteyl-CoA
,4. Which citrate cycle intermediate is known to be involved in the synthesis of
heme?
Citrate
Alpha-ketoglutarate
Isocitrate
Succinyl-CoA
5. Which statement regarding the Pyruvate Dehydrogenase reaction is correct?
Coenzyme A is irrevesibly metabolized, yielding NADH and acetyl
CoA.
Pyruvate is reduced to NADH and acetyl CoA.
Pyruvate undergoes oxidative decarboxylation, yielding NADH,
carbon dioxide and acetyl CoA.
The six carbon skeletons from the glycolytic intermediate pyruvate
are released as carbon dioxide.
Pyruvate is metabolized to lactic acid, yielding NADH.
6. Describe the significance of the reaction NADH + O2 --> H2O + NAD+ in the
context of cellular respiration.
This reaction shows that oxygen is reduced to form NADH, which is
used in the citric acid cycle.
This reaction is crucial as it represents the transfer of electrons from
NADH to oxygen, leading to the production of water and the
regeneration of NAD+, which is essential for glycolysis and the citric
acid cycle.
This reaction demonstrates the breakdown of glucose into pyruvate.
, This reaction indicates that NADH is converted into FADH2, which is
used in the electron transport chain.
7. Which of the following cofactors of pyruvate dehydrogenase is the target of
arsenic acid and mercury poisoning?
NAD+
FAD
Thiamine pyrophosphate
Lipoic acid
8. What is the typical membrane potential measured in millivolts (mV) for proton
transport across the mitochondrial inner membrane?
200 mV
180 mV
120 mV
160 mV
9. Which electron carrier in the electron transport chain is known to be soluble
and not attached to the inner mitochondrial membrane?
complex II
coenzyme Q
complex I
cytochrome c
10. If a drug inhibits the enzyme responsible for the conversion of pyruvate to
acetyl-CoA, what metabolic consequence might occur?
Increased glycolysis
, Increased lactate production
Enhanced ATP synthesis
Reduced production of acetyl-CoA
11. Citrate is transported out of the mitochondria into the cytosol for use in the
biosynthesis of:
amino acids
insulin
fatty acids
glucose
cholesterol
12. Describe how chloroplasts and mitochondria utilize the proton gradient in
ATP synthesis.
Chloroplasts and mitochondria use the energy from the proton
gradient to drive ATP synthesis through ATP synthase.
Chloroplasts and mitochondria convert the proton gradient into
glucose.
Chloroplasts and mitochondria use the proton gradient to transport
NADH.
Chloroplasts and mitochondria rely on the proton gradient for DNA
replication.
13. In your group: A comparison of mitochondria and chloroplasts shows that
they have very different electron transport protein complexes.
only mitochondria contain ATP synthase.
