BIOD 151 Cell Biology & Cell Membrane
Assessment 100 Questions Exam Prep with
Verified Answers Portage Learning Edition
2026/2027
SECTION A: CELLULAR ORGANIZATION & MEMBRANE
STRUCTURE (Questions 1-25)
1. What best describes the structure of cellular membranes?
• A) A solid protein matrix
• B) A carbohydrate shell
• C) A phospholipid bilayer with embedded proteins
• D) A single layer of lipids
Answer: C
Expert Rationale: Cell membranes consist of a phospholipid
bilayer with embedded proteins. This is the fundamental
principle of the fluid mosaic model, where phospholipids form the
basic barrier and proteins perform various functions including
transport, signaling, and cell recognition.
2. Which of the following accounts for the "fluid" designation
given to the plasma membrane?
• A) The movement of certain proteins and lipids within the bilayer
• B) The movement of substances across the membrane
,• C) The diffusion of certain lipid-soluble substances
• D) The membrane is water soluble
Answer: A
Expert Rationale: The "fluid" designation refers to the
movement of certain proteins and lipids within the bilayer.
Individual phospholipids can diffuse laterally within their leaflet,
and some proteins can also move within the plane of the
membrane.
3. How is the organization of the plasma membrane best
described?
• A) A double layer of phospholipid molecules in which
hydrophobic tails are directed outward
• B) A double layer of phospholipid molecules with hydrophilic
heads directed inward
• C) A double layer of phospholipid molecules with hydrophobic
tails oriented inward, toward each other
• D) A single layer of phospholipids with hydrophobic tails pointed
toward the cytoplasm
Answer: C
Expert Rationale: The plasma membrane is organized as a
double layer of phospholipid molecules with hydrophobic tails
oriented inward, toward each other. The hydrophilic heads face
outward toward the aqueous environments on both sides.
, 4. Cholesterol in the plasma membrane is responsible for
which of the following membrane properties?
• A) Receptor function
• B) Cell recognition
• C) Membrane fluidity
• D) Transport
Answer: C
Expert Rationale: Cholesterol in the plasma membrane is
responsible for regulating membrane fluidity. It intercalates
between phospholipid molecules and modulates fluidity across a
range of temperatures—reducing fluidity at warm temperatures
and preventing excessive rigidity at cool temperatures.
5. Peripheral proteins are found on the outer surface of a cell
membrane. (T or F)
• A) True
• B) False
Answer: A
Expert Rationale: Peripheral proteins are found on the outer
surface of a cell membrane. They are loosely attached to the
surface and do not penetrate the hydrophobic core.
, 6. The plasma membrane allows the passage of some
molecules while prohibiting the passage of others. Thus the
membrane is said to be:
• A) Permeable
• B) Semipermeable (selectively permeable)
• C) Porous
• D) Semiporous
Answer: B
Expert Rationale: The plasma membrane is described as
semipermeable or selectively permeable because it allows some
molecules to pass while prohibiting others. This property is
essential for maintaining cellular homeostasis.
7. Which component of the plasma membrane is primarily
responsible for its selective permeability?
• A) Membrane proteins
• B) Cholesterol
• C) Phospholipid bilayer
• D) Carbohydrate chains
Answer: C
Expert Rationale: The phospholipid bilayer forms the
fundamental barrier of the membrane. Its hydrophobic interior
prevents the passage of most water-soluble molecules, while
allowing small nonpolar molecules to diffuse through.
Assessment 100 Questions Exam Prep with
Verified Answers Portage Learning Edition
2026/2027
SECTION A: CELLULAR ORGANIZATION & MEMBRANE
STRUCTURE (Questions 1-25)
1. What best describes the structure of cellular membranes?
• A) A solid protein matrix
• B) A carbohydrate shell
• C) A phospholipid bilayer with embedded proteins
• D) A single layer of lipids
Answer: C
Expert Rationale: Cell membranes consist of a phospholipid
bilayer with embedded proteins. This is the fundamental
principle of the fluid mosaic model, where phospholipids form the
basic barrier and proteins perform various functions including
transport, signaling, and cell recognition.
2. Which of the following accounts for the "fluid" designation
given to the plasma membrane?
• A) The movement of certain proteins and lipids within the bilayer
• B) The movement of substances across the membrane
,• C) The diffusion of certain lipid-soluble substances
• D) The membrane is water soluble
Answer: A
Expert Rationale: The "fluid" designation refers to the
movement of certain proteins and lipids within the bilayer.
Individual phospholipids can diffuse laterally within their leaflet,
and some proteins can also move within the plane of the
membrane.
3. How is the organization of the plasma membrane best
described?
• A) A double layer of phospholipid molecules in which
hydrophobic tails are directed outward
• B) A double layer of phospholipid molecules with hydrophilic
heads directed inward
• C) A double layer of phospholipid molecules with hydrophobic
tails oriented inward, toward each other
• D) A single layer of phospholipids with hydrophobic tails pointed
toward the cytoplasm
Answer: C
Expert Rationale: The plasma membrane is organized as a
double layer of phospholipid molecules with hydrophobic tails
oriented inward, toward each other. The hydrophilic heads face
outward toward the aqueous environments on both sides.
, 4. Cholesterol in the plasma membrane is responsible for
which of the following membrane properties?
• A) Receptor function
• B) Cell recognition
• C) Membrane fluidity
• D) Transport
Answer: C
Expert Rationale: Cholesterol in the plasma membrane is
responsible for regulating membrane fluidity. It intercalates
between phospholipid molecules and modulates fluidity across a
range of temperatures—reducing fluidity at warm temperatures
and preventing excessive rigidity at cool temperatures.
5. Peripheral proteins are found on the outer surface of a cell
membrane. (T or F)
• A) True
• B) False
Answer: A
Expert Rationale: Peripheral proteins are found on the outer
surface of a cell membrane. They are loosely attached to the
surface and do not penetrate the hydrophobic core.
, 6. The plasma membrane allows the passage of some
molecules while prohibiting the passage of others. Thus the
membrane is said to be:
• A) Permeable
• B) Semipermeable (selectively permeable)
• C) Porous
• D) Semiporous
Answer: B
Expert Rationale: The plasma membrane is described as
semipermeable or selectively permeable because it allows some
molecules to pass while prohibiting others. This property is
essential for maintaining cellular homeostasis.
7. Which component of the plasma membrane is primarily
responsible for its selective permeability?
• A) Membrane proteins
• B) Cholesterol
• C) Phospholipid bilayer
• D) Carbohydrate chains
Answer: C
Expert Rationale: The phospholipid bilayer forms the
fundamental barrier of the membrane. Its hydrophobic interior
prevents the passage of most water-soluble molecules, while
allowing small nonpolar molecules to diffuse through.
