CHEM 210 Biochemistry Module 8 Practice
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2025
Q&A | Instant Download PDF
1. Which enzyme is directly activated by cAMP in the signal transduction
pathway?
A. Adenylate cyclase
B. Phosphodiesterase
C. Protein kinase A
D. Protein kinase C
Protein kinase A (PKA) is activated by cAMP, which binds to its
regulatory subunits and releases active catalytic subunits.
2. Which hormone primarily stimulates glycogen breakdown in muscle
cells?
A. Insulin
B. Glucagon
, C. Epinephrine
D. Cortisol
Epinephrine activates glycogen phosphorylase in muscle via β-
adrenergic receptors, increasing glucose availability during stress.
3. The main site for gluconeogenesis is:
A. Muscle
B. Brain
C. Liver
D. Adipose tissue
The liver is the major organ responsible for synthesizing glucose
through gluconeogenesis to maintain blood glucose levels.
4. Which of the following inhibits acetyl-CoA carboxylase?
A. Insulin
B. Citrate
C. Palmitoyl-CoA
D. Malonyl-CoA
Palmitoyl-CoA, a long-chain fatty acid, acts as a feedback inhibitor of
acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid
synthesis.
5. What is the main function of AMP-activated protein kinase (AMPK)?
A. Activate glycogen synthesis
B. Switch on catabolic pathways during low energy states
C. Inhibit glucose uptake
, D. Promote fatty acid synthesis
AMPK senses cellular energy status and activates pathways that
generate ATP while inhibiting anabolic processes.
6. Which hormone receptor type is most likely a nuclear receptor?
A. Thyroid hormone receptor
B. Epinephrine receptor
C. Insulin receptor
D. Glucagon receptor
Thyroid hormone receptors are intracellular nuclear receptors that
bind to DNA and modulate gene expression.
7. Which of the following is NOT a second messenger?
A. Diacylglycerol (DAG)
B. cAMP
C. Inositol triphosphate (IP3)
D. Insulin
Insulin is a peptide hormone; it acts through cell-surface receptors
but is not itself a second messenger.
8. Which enzyme catalyzes the rate-limiting step in cholesterol
synthesis?
A. Squalene synthase
B. Farnesyl pyrophosphate synthase
C. HMG-CoA reductase
D. Acetyl-CoA carboxylase
, HMG-CoA reductase converts HMG-CoA to mevalonate, the key
regulatory step in cholesterol biosynthesis.
9. What is the major metabolic effect of glucagon?
A. Increase glucose uptake in muscle
B. Increase glycolysis in liver
C. Promote gluconeogenesis and glycogenolysis
D. Stimulate fatty acid synthesis
Glucagon acts mainly on the liver to raise blood glucose by
stimulating glycogen breakdown and glucose production.
10. Which signaling molecule binds to G-protein coupled receptors?
A. Insulin
B. Epinephrine
C. Cortisol
D. Thyroxine
Epinephrine binds to β-adrenergic GPCRs, triggering cAMP
production and downstream effects.
11. The insulin receptor has which type of intrinsic enzymatic
activity?
A. Adenylyl cyclase
B. Guanylate cyclase
C. Tyrosine kinase
D. Phospholipase C
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2025
Q&A | Instant Download PDF
1. Which enzyme is directly activated by cAMP in the signal transduction
pathway?
A. Adenylate cyclase
B. Phosphodiesterase
C. Protein kinase A
D. Protein kinase C
Protein kinase A (PKA) is activated by cAMP, which binds to its
regulatory subunits and releases active catalytic subunits.
2. Which hormone primarily stimulates glycogen breakdown in muscle
cells?
A. Insulin
B. Glucagon
, C. Epinephrine
D. Cortisol
Epinephrine activates glycogen phosphorylase in muscle via β-
adrenergic receptors, increasing glucose availability during stress.
3. The main site for gluconeogenesis is:
A. Muscle
B. Brain
C. Liver
D. Adipose tissue
The liver is the major organ responsible for synthesizing glucose
through gluconeogenesis to maintain blood glucose levels.
4. Which of the following inhibits acetyl-CoA carboxylase?
A. Insulin
B. Citrate
C. Palmitoyl-CoA
D. Malonyl-CoA
Palmitoyl-CoA, a long-chain fatty acid, acts as a feedback inhibitor of
acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid
synthesis.
5. What is the main function of AMP-activated protein kinase (AMPK)?
A. Activate glycogen synthesis
B. Switch on catabolic pathways during low energy states
C. Inhibit glucose uptake
, D. Promote fatty acid synthesis
AMPK senses cellular energy status and activates pathways that
generate ATP while inhibiting anabolic processes.
6. Which hormone receptor type is most likely a nuclear receptor?
A. Thyroid hormone receptor
B. Epinephrine receptor
C. Insulin receptor
D. Glucagon receptor
Thyroid hormone receptors are intracellular nuclear receptors that
bind to DNA and modulate gene expression.
7. Which of the following is NOT a second messenger?
A. Diacylglycerol (DAG)
B. cAMP
C. Inositol triphosphate (IP3)
D. Insulin
Insulin is a peptide hormone; it acts through cell-surface receptors
but is not itself a second messenger.
8. Which enzyme catalyzes the rate-limiting step in cholesterol
synthesis?
A. Squalene synthase
B. Farnesyl pyrophosphate synthase
C. HMG-CoA reductase
D. Acetyl-CoA carboxylase
, HMG-CoA reductase converts HMG-CoA to mevalonate, the key
regulatory step in cholesterol biosynthesis.
9. What is the major metabolic effect of glucagon?
A. Increase glucose uptake in muscle
B. Increase glycolysis in liver
C. Promote gluconeogenesis and glycogenolysis
D. Stimulate fatty acid synthesis
Glucagon acts mainly on the liver to raise blood glucose by
stimulating glycogen breakdown and glucose production.
10. Which signaling molecule binds to G-protein coupled receptors?
A. Insulin
B. Epinephrine
C. Cortisol
D. Thyroxine
Epinephrine binds to β-adrenergic GPCRs, triggering cAMP
production and downstream effects.
11. The insulin receptor has which type of intrinsic enzymatic
activity?
A. Adenylyl cyclase
B. Guanylate cyclase
C. Tyrosine kinase
D. Phospholipase C
