CHEM 210 Biochemistry Module 4 Exam
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Q1. Which of the following best defines a lipid?
A) Polymers of amino acids
B) Water-soluble macromolecules
C) Hydrophobic or amphipathic biomolecules ✅
D) Carbohydrate derivatives
Rationale: Lipids are defined by solubility in nonpolar solvents
and include fats, steroids, phospholipids.
Q2. Which lipid is completely hydrophobic (no polar head
group)?
A) Phospholipid
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B) Triacylglycerol ✅
C) Sphingolipid
D) Ganglioside
Rationale: Triacylglycerols have three fatty acids esterified to
glycerol, no charged/polar group.
Q3. A fatty acid with the formula 18:2(Δ⁹,¹²) has:
A) 18 carbons, 2 double bonds at positions 9 and 12 ✅
B) 18 carbons, 2 double bonds at positions 1 and 2
C) 2 carbons, 18 double bonds
D) 18 double bonds, 2 carbons
Rationale: Standard notation: C:D(Δ positions). 18:2 means 18
carbons, 2 double bonds.
Q4. Which fatty acid is essential in humans?
A) Palmitic acid (16:0)
B) Stearic acid (18:0)
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C) Linoleic acid (18:2Δ⁹,¹²) ✅
D) Arachidic acid (20:0)
Rationale: Linoleic (omega-6) and α-linolenic (omega-3) are
essential; humans lack Δ12 and Δ15 desaturases.
Q5. Saturated fatty acids have:
A) One or more double bonds in cis configuration
B) No double bonds, maximum hydrogens ✅
C) Kinked chains
D) Lower melting point than unsaturated
Rationale: Saturated = all single bonds, straight chains, higher
melting point.
Q6. Which lipid is a major component of cell membranes?
A) Triacylglycerol
B) Cholesterol ✅
C) Wax ester
D) Free fatty acid
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Rationale: Cholesterol is a membrane lipid; triacylglycerols
are storage.
Q7. Sphingosine is the backbone for:
A) Glycerophospholipids
B) Sphingolipids ✅
C) Triacylglycerols
D) Waxes
Rationale: Sphingolipids contain sphingosine instead of
glycerol.
Q8. A cerebroside contains:
A) Sphingosine + fatty acid + glucose or galactose ✅
B) Glycerol + two fatty acids + phosphate
C) Sphingosine + fatty acid + sialic acid
D) Cholesterol + fatty acid
Rationale: Cerebrosides are simple glycosphingolipids with
one sugar.