CHEM 210 Module 5: Lipids and Lipid Metabolism 2026/2027 UPDATE
1. Which of the following is a characteristic of all lipids?
A. They are all polymers of fatty acids.
B. They are all strictly used for energy storage.
C. They all contain a glycerol backbone.
D. They are largely hydrophobic and insoluble in water.
Answer: D
Rationale: Lipids are a diverse group of compounds defined by their hydrophobicity and
solubility in nonpolar solvents rather than a shared chemical structure.
2. Which fatty acid is considered an essential fatty acid that humans must
obtain from their diet?
A. Palmitic acid
B. Stearic acid
C. Oleic acid
D. Linoleic acid
Answer: D
Rationale: Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) are essential
because humans lack the enzymes to insert double bonds beyond carbon 9.
3. How many carbons are typically found in a molecule of palmitic acid?
A. 12
B. 14
C. 18
D. 16
Answer: D
,Rationale: Palmitic acid is a common 16-carbon saturated fatty acid and is the primary
product of fatty acid synthase.
4. Triacylglycerols are composed of three fatty acids linked to which molecule
via ester bonds?
A. Sphingosine
B. Cholesterol
C. Glycerol
D. Ethanolamine
Answer: C
Rationale: Triacylglycerols (fats/oils) consist of a glycerol backbone esterified to three
fatty acid chains.
5. Which enzyme is responsible for the activation of fatty acids by attaching
them to Coenzyme A?
A. Lipoprotein lipase
B. Carnitine acyltransferase I
C. Thiolase
D. Acyl-CoA synthetase
Answer: D
Rationale: Acyl-CoA synthetase (also called fatty acid thiokinase) catalyzes the ATP-
dependent activation of fatty acids to form acyl-CoA.
6. The carnitine shuttle is required to transport long-chain fatty acids into which
cellular compartment?
A. Nucleus
B. Mitochondrial matrix
C. Endoplasmic reticulum
D. Lysosome
Answer: B
, Rationale: Fatty acid oxidation occurs in the mitochondrial matrix, and long-chain acyl-
CoAs cannot cross the inner membrane without the carnitine transport system.
7. What is the first step in the beta-oxidation of a saturated fatty acid?
A. Oxidation by FAD
B. Thiolysis
C. Hydration
D. Oxidation by NAD+
Answer: A
Rationale: The first step is the oxidation of the acyl-CoA by FAD, catalyzed by acyl-CoA
dehydrogenase, forming a trans-double bond.
8. Each cycle of beta-oxidation shortens the fatty acid chain by how many
carbons?
A. 1
B. 2
C. 3
D. 4
Answer: B
Rationale: Beta-oxidation removes two carbons at a time in the form of Acetyl-CoA.
9. What is the net yield of ATP from the complete oxidation of one palmitate
(16:0) molecule?
A. 106 ATP
B. 32 ATP
C. 129 ATP
D. 146 ATP
Answer: A
1. Which of the following is a characteristic of all lipids?
A. They are all polymers of fatty acids.
B. They are all strictly used for energy storage.
C. They all contain a glycerol backbone.
D. They are largely hydrophobic and insoluble in water.
Answer: D
Rationale: Lipids are a diverse group of compounds defined by their hydrophobicity and
solubility in nonpolar solvents rather than a shared chemical structure.
2. Which fatty acid is considered an essential fatty acid that humans must
obtain from their diet?
A. Palmitic acid
B. Stearic acid
C. Oleic acid
D. Linoleic acid
Answer: D
Rationale: Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) are essential
because humans lack the enzymes to insert double bonds beyond carbon 9.
3. How many carbons are typically found in a molecule of palmitic acid?
A. 12
B. 14
C. 18
D. 16
Answer: D
,Rationale: Palmitic acid is a common 16-carbon saturated fatty acid and is the primary
product of fatty acid synthase.
4. Triacylglycerols are composed of three fatty acids linked to which molecule
via ester bonds?
A. Sphingosine
B. Cholesterol
C. Glycerol
D. Ethanolamine
Answer: C
Rationale: Triacylglycerols (fats/oils) consist of a glycerol backbone esterified to three
fatty acid chains.
5. Which enzyme is responsible for the activation of fatty acids by attaching
them to Coenzyme A?
A. Lipoprotein lipase
B. Carnitine acyltransferase I
C. Thiolase
D. Acyl-CoA synthetase
Answer: D
Rationale: Acyl-CoA synthetase (also called fatty acid thiokinase) catalyzes the ATP-
dependent activation of fatty acids to form acyl-CoA.
6. The carnitine shuttle is required to transport long-chain fatty acids into which
cellular compartment?
A. Nucleus
B. Mitochondrial matrix
C. Endoplasmic reticulum
D. Lysosome
Answer: B
, Rationale: Fatty acid oxidation occurs in the mitochondrial matrix, and long-chain acyl-
CoAs cannot cross the inner membrane without the carnitine transport system.
7. What is the first step in the beta-oxidation of a saturated fatty acid?
A. Oxidation by FAD
B. Thiolysis
C. Hydration
D. Oxidation by NAD+
Answer: A
Rationale: The first step is the oxidation of the acyl-CoA by FAD, catalyzed by acyl-CoA
dehydrogenase, forming a trans-double bond.
8. Each cycle of beta-oxidation shortens the fatty acid chain by how many
carbons?
A. 1
B. 2
C. 3
D. 4
Answer: B
Rationale: Beta-oxidation removes two carbons at a time in the form of Acetyl-CoA.
9. What is the net yield of ATP from the complete oxidation of one palmitate
(16:0) molecule?
A. 106 ATP
B. 32 ATP
C. 129 ATP
D. 146 ATP
Answer: A
