,CHEM212/CHEM 212 Module 5 Exam Biochemistry
with Lab | Portage Learning | 26/27 Actual(PDF)
1. A lipid is defined functionally as a carbon compound that dissolves in which type of solvent?
A) Polar solvents such as water
B) Nonpolar solvents such as ether
C) Aqueous buffers at physiological pH
D) Ionic solutions containing salts
Correct Answer: Nonpolar solvents such as ether
Rationale: The module defines lipids functionally by their solubility, not by a specific structural
feature. Lipids dissolve in nonpolar organic solvents such as ether, chloroform, or benzene, and are
generally insoluble in water. This solubility-based definition distinguishes lipids from carbohydrates,
proteins, and nucleic acids.
2. How many alcohol functional groups are present on a glycerol molecule?
A) One
B) Two
C) Three
D) Four
Correct Answer: Three
Rationale: Glycerol is a three-carbon molecule with a hydroxyl group on each carbon, giving it three
alcohol functional groups. This triol structure allows glycerol to form ester linkages with up to three
fatty acids, producing triacylglycerols. The correct number is three, not one, two, or four.
3. A triacylglycerol is formed by the esterification of glycerol with how many fatty acid molecules?
A) One
B) Two
,C) Three
D) Four
Correct Answer: Three
Rationale: Triacylglycerols consist of a glycerol backbone esterified to three fatty acid chains at all
three hydroxyl positions. Diacylglycerols have two fatty acids, and monoacylglycerols have one. The
prefix tri- explicitly indicates three fatty acid chains.
4. Which type of linkage attaches fatty acids to the glycerol backbone in a triacylglycerol?
A) Amide linkage
B) Ester linkage
C) Ether linkage
D) Peptide linkage
Correct Answer: Ester linkage
Rationale: Fatty acids are attached to glycerol via ester bonds formed between the carboxyl group of
the fatty acid and the hydroxyl group of glycerol, with the release of water. Amide linkages occur in
sphingolipids, ether linkages appear in plasmalogens, and peptide linkages are found in proteins.
5. A particular lipid is solid at room temperature. This lipid is best classified as which of the following?
A) An oil
B) A fat
C) A wax
D) A sterol
Correct Answer: A fat
, Rationale: Fats are triacylglycerols that are solid at room temperature, typically because they contain
a high proportion of saturated fatty acids. Oils are liquid at room temperature due to higher
unsaturated fatty acid content. Waxes are esters of long-chain fatty acids with long-chain alcohols,
and sterols have a fused-ring structure.
6. Which statement correctly distinguishes saturated from unsaturated fatty acids?
A) Saturated fatty acids contain carbon-carbon double bonds
B) Unsaturated fatty acids contain only single bonds between carbons
C) Saturated fatty acids have no carbon-carbon double bonds in their hydrocarbon chain
D) Unsaturated fatty acids are always solid at room temperature
Correct Answer: Saturated fatty acids have no carbon-carbon double bonds in their hydrocarbon chain
Rationale: Saturated fatty acids are fully saturated with hydrogen and contain only single bonds
between carbon atoms, making them straight-chain molecules that pack tightly. Unsaturated fatty
acids contain one or more double bonds, which introduce kinks and prevent tight packing. This
structural difference explains why unsaturated fats are typically liquid at room temperature.
7. Palmitic acid has the shorthand notation 16:0. What does the "0" indicate?
A) The number of carbon atoms
B) The number of double bonds
C) The position of the first double bond
D) The number of hydroxyl groups
Correct Answer: The number of double bonds
Rationale: In the shorthand notation C:D, C represents the number of carbon atoms and D represents
the number of double bonds. Palmitic acid has 16 carbons and zero double bonds, making it a
saturated fatty acid. The first number (16) indicates carbon count, and the second number (0)
indicates double bond count.
8. Oleic acid is represented as 18:1 Δ⁹. What does the Δ⁹ indicate?
with Lab | Portage Learning | 26/27 Actual(PDF)
1. A lipid is defined functionally as a carbon compound that dissolves in which type of solvent?
A) Polar solvents such as water
B) Nonpolar solvents such as ether
C) Aqueous buffers at physiological pH
D) Ionic solutions containing salts
Correct Answer: Nonpolar solvents such as ether
Rationale: The module defines lipids functionally by their solubility, not by a specific structural
feature. Lipids dissolve in nonpolar organic solvents such as ether, chloroform, or benzene, and are
generally insoluble in water. This solubility-based definition distinguishes lipids from carbohydrates,
proteins, and nucleic acids.
2. How many alcohol functional groups are present on a glycerol molecule?
A) One
B) Two
C) Three
D) Four
Correct Answer: Three
Rationale: Glycerol is a three-carbon molecule with a hydroxyl group on each carbon, giving it three
alcohol functional groups. This triol structure allows glycerol to form ester linkages with up to three
fatty acids, producing triacylglycerols. The correct number is three, not one, two, or four.
3. A triacylglycerol is formed by the esterification of glycerol with how many fatty acid molecules?
A) One
B) Two
,C) Three
D) Four
Correct Answer: Three
Rationale: Triacylglycerols consist of a glycerol backbone esterified to three fatty acid chains at all
three hydroxyl positions. Diacylglycerols have two fatty acids, and monoacylglycerols have one. The
prefix tri- explicitly indicates three fatty acid chains.
4. Which type of linkage attaches fatty acids to the glycerol backbone in a triacylglycerol?
A) Amide linkage
B) Ester linkage
C) Ether linkage
D) Peptide linkage
Correct Answer: Ester linkage
Rationale: Fatty acids are attached to glycerol via ester bonds formed between the carboxyl group of
the fatty acid and the hydroxyl group of glycerol, with the release of water. Amide linkages occur in
sphingolipids, ether linkages appear in plasmalogens, and peptide linkages are found in proteins.
5. A particular lipid is solid at room temperature. This lipid is best classified as which of the following?
A) An oil
B) A fat
C) A wax
D) A sterol
Correct Answer: A fat
, Rationale: Fats are triacylglycerols that are solid at room temperature, typically because they contain
a high proportion of saturated fatty acids. Oils are liquid at room temperature due to higher
unsaturated fatty acid content. Waxes are esters of long-chain fatty acids with long-chain alcohols,
and sterols have a fused-ring structure.
6. Which statement correctly distinguishes saturated from unsaturated fatty acids?
A) Saturated fatty acids contain carbon-carbon double bonds
B) Unsaturated fatty acids contain only single bonds between carbons
C) Saturated fatty acids have no carbon-carbon double bonds in their hydrocarbon chain
D) Unsaturated fatty acids are always solid at room temperature
Correct Answer: Saturated fatty acids have no carbon-carbon double bonds in their hydrocarbon chain
Rationale: Saturated fatty acids are fully saturated with hydrogen and contain only single bonds
between carbon atoms, making them straight-chain molecules that pack tightly. Unsaturated fatty
acids contain one or more double bonds, which introduce kinks and prevent tight packing. This
structural difference explains why unsaturated fats are typically liquid at room temperature.
7. Palmitic acid has the shorthand notation 16:0. What does the "0" indicate?
A) The number of carbon atoms
B) The number of double bonds
C) The position of the first double bond
D) The number of hydroxyl groups
Correct Answer: The number of double bonds
Rationale: In the shorthand notation C:D, C represents the number of carbon atoms and D represents
the number of double bonds. Palmitic acid has 16 carbons and zero double bonds, making it a
saturated fatty acid. The first number (16) indicates carbon count, and the second number (0)
indicates double bond count.
8. Oleic acid is represented as 18:1 Δ⁹. What does the Δ⁹ indicate?
