PORTAGE LEARNING CHEM 210 MODULE 5 PROBLEM
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
Which membrane component often serves as a signal-binding protein?
A. Glycerol molecule
B. Receptor
C. Free fatty acid tail
D. Triacylglycerol droplet
Correct Answer: B. Receptor
Explanation: Receptor follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 2.
A laboratory observation shows that no transporter or metabolic energy is required. Which
concept best explains this finding?
A. Simple diffusion
B. Omega notation
C. Monounsaturated fatty acid
D. Trans double bond
Correct Answer: A. Simple diffusion
Explanation: Simple diffusion best explains the observation because simple diffusion
moves small nonpolar molecules down their concentration gradient directly through the
lipid bilayer. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 3.
Consider the following description. Which term matches the following description:
Membrane fluidity reflects how freely lipids and proteins move within the bilayer and is
influenced by temperature, chain length, unsaturation, and cholesterol.
A. Polyunsaturated fatty acid
B. Cholesterol
C. Membrane fluidity
D. Fat
Correct Answer: C. Membrane fluidity
Explanation: Membrane fluidity is defined by this description. The key identifying feature
is that more cis unsaturation usually increases fluidity at a given temperature. The other
choices refer to distinct concepts within lipid classes, fatty-acid nomenclature, storage
,lipids, membrane lipids, cholesterol, and membrane organization and do not match all
parts of the description.
Question 4.
A laboratory observation shows that it is abundant in many cellular membranes. Which
concept best explains this finding?
A. Lipid raft
B. Cholesterol
C. Oil
D. Phosphatidylethanolamine
Correct Answer: D. Phosphatidylethanolamine
Explanation: Phosphatidylethanolamine best explains the observation because
phosphatidylethanolamine is a glycerophospholipid containing ethanolamine as its polar
head group. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 5.
An 18:3 Delta9,12,15 fatty acid belongs to which omega family?
A. Omega-3
B. Omega-6
C. Omega-9
D. Omega-15
Correct Answer: A. Omega-3
Explanation: Omega-3 follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 6.
A laboratory observation shows that its small hydroxyl group aligns near phospholipid
head groups while the rings insert among acyl chains. Which concept best explains this
finding?
A. Transmembrane protein
B. Channel protein
C. Cholesterol
D. Amphipathic molecule
Correct Answer: C. Cholesterol
Explanation: Cholesterol best explains the observation because cholesterol is an
amphipathic sterol that modulates animal membrane fluidity and serves as a precursor of
steroid hormones and bile acids. The clue in the stem points directly to this mechanism or
,structural feature. The other options involve different biochemical properties and therefore
do not account for the observation as well.
Question 7.
Which statement about Simple diffusion is most accurate?
A. A monounsaturated fatty acid contains one carbon-carbon double bond.
B. A trans double bond leaves a fatty-acid chain more extended and allows tighter packing
than a cis bond.
C. Omega notation classifies an unsaturated fatty acid by the position of the first double
bond counted from the methyl end.
D. Simple diffusion moves small nonpolar molecules down their concentration gradient
directly through the lipid bilayer.
Correct Answer: D. Simple diffusion moves small nonpolar molecules down their
concentration gradient directly through the lipid bilayer.
Explanation: Simple diffusion moves small nonpolar molecules down their concentration
gradient directly through the lipid bilayer. This is the defining chemistry of Simple
diffusion. The alternative statements describe other concepts and would misclassify the
structure, force, or process under discussion.
Question 8.
A laboratory observation shows that carrier-mediated transport is saturable because the
number of binding sites is finite. Which concept best explains this finding?
A. Cholesterol as fluidity buffer
B. Carrier protein
C. Phosphatidylethanolamine
D. Fatty acid
Correct Answer: B. Carrier protein
Explanation: Carrier protein best explains the observation because a carrier protein binds
a solute and changes conformation to move it across the membrane. The clue in the stem
points directly to this mechanism or structural feature. The other options involve different
biochemical properties and therefore do not account for the observation as well.
Question 9.
Which option best identifies the following description: Sphingosine is a long-chain amino
alcohol that serves as the backbone of sphingolipids.
A. Ester linkage
B. Ceramide
C. Sphingosine
D. Delta notation
Correct Answer: C. Sphingosine
, Explanation: Sphingosine is defined by this description. The key identifying feature is
that it replaces glycerol as the core scaffold in this lipid class. The other choices refer to
distinct concepts within lipid classes, fatty-acid nomenclature, storage lipids, membrane
lipids, cholesterol, and membrane organization and do not match all parts of the
description.
Question 10.
A laboratory observation shows that ligand binding can trigger conformational or
biochemical changes. Which concept best explains this finding?
A. Membrane receptor
B. Ceramide
C. Lipid
D. Trans double bond
Correct Answer: A. Membrane receptor
Explanation: Membrane receptor best explains the observation because a membrane
receptor binds a signaling molecule and transduces information across or within the
membrane. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 11.
Which class contains cholesterol?
A. Fatty acids only
B. Sterols
C. Triacylglycerols
D. Glycerophospholipids
Correct Answer: B. Sterols
Explanation: Sterols follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 12.
A laboratory observation shows that 18:1 Delta9 denotes an 18-carbon fatty acid with a
double bond between C9 and C10. Which concept best explains this finding?
A. Selective permeability
B. Essential fatty acid
C. Cholesterol
D. Delta notation
Correct Answer: D. Delta notation
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
Which membrane component often serves as a signal-binding protein?
A. Glycerol molecule
B. Receptor
C. Free fatty acid tail
D. Triacylglycerol droplet
Correct Answer: B. Receptor
Explanation: Receptor follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 2.
A laboratory observation shows that no transporter or metabolic energy is required. Which
concept best explains this finding?
A. Simple diffusion
B. Omega notation
C. Monounsaturated fatty acid
D. Trans double bond
Correct Answer: A. Simple diffusion
Explanation: Simple diffusion best explains the observation because simple diffusion
moves small nonpolar molecules down their concentration gradient directly through the
lipid bilayer. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 3.
Consider the following description. Which term matches the following description:
Membrane fluidity reflects how freely lipids and proteins move within the bilayer and is
influenced by temperature, chain length, unsaturation, and cholesterol.
A. Polyunsaturated fatty acid
B. Cholesterol
C. Membrane fluidity
D. Fat
Correct Answer: C. Membrane fluidity
Explanation: Membrane fluidity is defined by this description. The key identifying feature
is that more cis unsaturation usually increases fluidity at a given temperature. The other
choices refer to distinct concepts within lipid classes, fatty-acid nomenclature, storage
,lipids, membrane lipids, cholesterol, and membrane organization and do not match all
parts of the description.
Question 4.
A laboratory observation shows that it is abundant in many cellular membranes. Which
concept best explains this finding?
A. Lipid raft
B. Cholesterol
C. Oil
D. Phosphatidylethanolamine
Correct Answer: D. Phosphatidylethanolamine
Explanation: Phosphatidylethanolamine best explains the observation because
phosphatidylethanolamine is a glycerophospholipid containing ethanolamine as its polar
head group. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 5.
An 18:3 Delta9,12,15 fatty acid belongs to which omega family?
A. Omega-3
B. Omega-6
C. Omega-9
D. Omega-15
Correct Answer: A. Omega-3
Explanation: Omega-3 follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 6.
A laboratory observation shows that its small hydroxyl group aligns near phospholipid
head groups while the rings insert among acyl chains. Which concept best explains this
finding?
A. Transmembrane protein
B. Channel protein
C. Cholesterol
D. Amphipathic molecule
Correct Answer: C. Cholesterol
Explanation: Cholesterol best explains the observation because cholesterol is an
amphipathic sterol that modulates animal membrane fluidity and serves as a precursor of
steroid hormones and bile acids. The clue in the stem points directly to this mechanism or
,structural feature. The other options involve different biochemical properties and therefore
do not account for the observation as well.
Question 7.
Which statement about Simple diffusion is most accurate?
A. A monounsaturated fatty acid contains one carbon-carbon double bond.
B. A trans double bond leaves a fatty-acid chain more extended and allows tighter packing
than a cis bond.
C. Omega notation classifies an unsaturated fatty acid by the position of the first double
bond counted from the methyl end.
D. Simple diffusion moves small nonpolar molecules down their concentration gradient
directly through the lipid bilayer.
Correct Answer: D. Simple diffusion moves small nonpolar molecules down their
concentration gradient directly through the lipid bilayer.
Explanation: Simple diffusion moves small nonpolar molecules down their concentration
gradient directly through the lipid bilayer. This is the defining chemistry of Simple
diffusion. The alternative statements describe other concepts and would misclassify the
structure, force, or process under discussion.
Question 8.
A laboratory observation shows that carrier-mediated transport is saturable because the
number of binding sites is finite. Which concept best explains this finding?
A. Cholesterol as fluidity buffer
B. Carrier protein
C. Phosphatidylethanolamine
D. Fatty acid
Correct Answer: B. Carrier protein
Explanation: Carrier protein best explains the observation because a carrier protein binds
a solute and changes conformation to move it across the membrane. The clue in the stem
points directly to this mechanism or structural feature. The other options involve different
biochemical properties and therefore do not account for the observation as well.
Question 9.
Which option best identifies the following description: Sphingosine is a long-chain amino
alcohol that serves as the backbone of sphingolipids.
A. Ester linkage
B. Ceramide
C. Sphingosine
D. Delta notation
Correct Answer: C. Sphingosine
, Explanation: Sphingosine is defined by this description. The key identifying feature is
that it replaces glycerol as the core scaffold in this lipid class. The other choices refer to
distinct concepts within lipid classes, fatty-acid nomenclature, storage lipids, membrane
lipids, cholesterol, and membrane organization and do not match all parts of the
description.
Question 10.
A laboratory observation shows that ligand binding can trigger conformational or
biochemical changes. Which concept best explains this finding?
A. Membrane receptor
B. Ceramide
C. Lipid
D. Trans double bond
Correct Answer: A. Membrane receptor
Explanation: Membrane receptor best explains the observation because a membrane
receptor binds a signaling molecule and transduces information across or within the
membrane. The clue in the stem points directly to this mechanism or structural feature.
The other options involve different biochemical properties and therefore do not account for
the observation as well.
Question 11.
Which class contains cholesterol?
A. Fatty acids only
B. Sterols
C. Triacylglycerols
D. Glycerophospholipids
Correct Answer: B. Sterols
Explanation: Sterols follows from the defining structure, nomenclature, or membrane
behavior described in the stem. The distractors conflict with lipid backbone chemistry,
fatty-acid packing, or transporter mechanism. Module 5 problems are most reliably solved
by connecting molecular structure to solubility, packing, and membrane function.
Question 12.
A laboratory observation shows that 18:1 Delta9 denotes an 18-carbon fatty acid with a
double bond between C9 and C10. Which concept best explains this finding?
A. Selective permeability
B. Essential fatty acid
C. Cholesterol
D. Delta notation
Correct Answer: D. Delta notation
