,CHEM 210 Exam 5 | Biochemistry Exam Q&A
| Portage Learning
1. Which of the following is the best definition of a lipid?
A) A polymer of amino acids linked by peptide bonds
B) A molecule that is soluble in nonpolar organic solvents
C) A polyhydroxy aldehyde or ketone
D) A nitrogenous base linked to a pentose sugar
Correct Answer: A molecule that is soluble in nonpolar organic solvents
Rationale: Lipids are defined by their solubility in nonpolar solvents rather than by a
specific structural feature. This functional definition includes fats, oils, steroids, and
waxes. Proteins and carbohydrates are defined by their characteristic structures.
2. Which of the following is NOT a biological function of lipids?
A) Energy storage
B) Membrane structure
C) Catalysis of metabolic reactions
D) Insulation and protection
Correct Answer: Catalysis of metabolic reactions
,Rationale: Lipids serve as energy stores, form membrane bilayers, and provide
insulation, but they do not catalyze biochemical reactions. Catalysis is a function of
enzymes, which are proteins. This distinction is fundamental to understanding
biomolecule roles.
3. What is the structural difference between a fat and an oil?
A) Fats contain glycerol; oils do not
B) Fats are solid at room temperature; oils are liquid
C) Fats contain phosphate; oils do not
D) Fats are made from sphingosine; oils are made from glycerol
Correct Answer: Fats are solid at room temperature; oils are liquid
Rationale: The terms fat and oil describe the physical state of a lipid at room
temperature. Fats are solid, while oils are liquid. This difference is due to the degree of
unsaturation in their fatty acid chains, not to differences in backbone structure.
4. Glycerol contains how many alcohol functional groups?
A) 1
B) 2
C) 3
D) 4
Correct Answer: 3
, Rationale: Glycerol is a three-carbon molecule with three hydroxyl (-OH) groups, one
on each carbon. These three alcohol groups allow glycerol to form ester linkages with
three fatty acids, creating a triacylglycerol.
5. Which of the following molecules serves as the backbone for triacylglycerols and
phosphoglycerides?
A) Sphingosine
B) Glycerol
C) Cholesterol
D) Ceramide
Correct Answer: Glycerol
Rationale: Glycerol is a three-carbon alcohol that serves as the backbone for
triacylglycerols and phosphoglycerides. Sphingosine is the backbone for sphingolipids,
and cholesterol is a sterol with a four-ring structure.
6. A fatty acid with no carbon-carbon double bonds is classified as:
A) Saturated
B) Monounsaturated
C) Polyunsaturated
D) Unsaturated
Correct Answer: Saturated
| Portage Learning
1. Which of the following is the best definition of a lipid?
A) A polymer of amino acids linked by peptide bonds
B) A molecule that is soluble in nonpolar organic solvents
C) A polyhydroxy aldehyde or ketone
D) A nitrogenous base linked to a pentose sugar
Correct Answer: A molecule that is soluble in nonpolar organic solvents
Rationale: Lipids are defined by their solubility in nonpolar solvents rather than by a
specific structural feature. This functional definition includes fats, oils, steroids, and
waxes. Proteins and carbohydrates are defined by their characteristic structures.
2. Which of the following is NOT a biological function of lipids?
A) Energy storage
B) Membrane structure
C) Catalysis of metabolic reactions
D) Insulation and protection
Correct Answer: Catalysis of metabolic reactions
,Rationale: Lipids serve as energy stores, form membrane bilayers, and provide
insulation, but they do not catalyze biochemical reactions. Catalysis is a function of
enzymes, which are proteins. This distinction is fundamental to understanding
biomolecule roles.
3. What is the structural difference between a fat and an oil?
A) Fats contain glycerol; oils do not
B) Fats are solid at room temperature; oils are liquid
C) Fats contain phosphate; oils do not
D) Fats are made from sphingosine; oils are made from glycerol
Correct Answer: Fats are solid at room temperature; oils are liquid
Rationale: The terms fat and oil describe the physical state of a lipid at room
temperature. Fats are solid, while oils are liquid. This difference is due to the degree of
unsaturation in their fatty acid chains, not to differences in backbone structure.
4. Glycerol contains how many alcohol functional groups?
A) 1
B) 2
C) 3
D) 4
Correct Answer: 3
, Rationale: Glycerol is a three-carbon molecule with three hydroxyl (-OH) groups, one
on each carbon. These three alcohol groups allow glycerol to form ester linkages with
three fatty acids, creating a triacylglycerol.
5. Which of the following molecules serves as the backbone for triacylglycerols and
phosphoglycerides?
A) Sphingosine
B) Glycerol
C) Cholesterol
D) Ceramide
Correct Answer: Glycerol
Rationale: Glycerol is a three-carbon alcohol that serves as the backbone for
triacylglycerols and phosphoglycerides. Sphingosine is the backbone for sphingolipids,
and cholesterol is a sterol with a four-ring structure.
6. A fatty acid with no carbon-carbon double bonds is classified as:
A) Saturated
B) Monounsaturated
C) Polyunsaturated
D) Unsaturated
Correct Answer: Saturated
