BIO 202 practice exam 2
When a membrane is freeze-fractured, the bilayer splits down the middle between the
two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane,
the bumps seen on the fractured surface of the membrane are
a. integral proteins.
b. ice crystals
c. carbohydrates.
d. platinum
e. cholesterol molecules. - answera. integral proteins.
An animal cell lacking oligosaccharides on the external surface of its plasma membrane
would likely be impaired in which function?
a. cell-cell recognition
b. attaching to the cytoskeleton
c. establishing the diffusion barrier to charged molecules
d. transporting ions against an electrochemical gradient
e. maintaining fluidity of the phospholipid bilaye - answera. cell-cell recognition
Water passes quickly through cell membranes because
a. it is a small, polar, charged molecule.
b. there are hydrophobic channels
c. it moves through aquaporins in the membrane.
d. cells are always hypotonic to their environment
e. the bilayer is amphipathic - answerc. it moves through aquaporins in the membrane.
In order for a protein to be an integral membrane protein it would have to be which of
the following?
a. completely covered with phospholipids
b. amphipathic
c. hydrophilic
d. hydrophobic
e. exposed on only one surface of the membrane - answerb. amphipathic
The transmission of nerve impulses between adjacent nerve cells often requires the
release of a peptide neurotransmitter into the synapse by the process of exocytosis. To
quench the signal, these neurotransmitters are then selectively internalized (taken back
into cells) by a process known as...
a. passive transport
b. phagocytosis
c. receptor-mediated endocytosis
d. signal transduction
e. facilitated diffusion - answerc. receptor-mediated endocytosis
, Celery stalks that are standing in a glass of pure water for several hours become stiff.
Other celery stalks that are standing in a glass of salt-water become limp. From this we
can predict that ....
a. the cells of the celery stalks are hypertonic to the pure water and isotonic to the salt-
water
b. the cells of the celery stalks are isotonic to the pure water and hypertonic to the salt-
water
c. the cells of the celery stalks are hypertonic to both the pure water and to the salt-
water
d. the cells of the celery stalks are hypertonic to the pure water and hypotonic to the
salt-water
e. the cells of the celery stalks are hypotonic to the pure water and hypertonic to the
salt-water - answerd. the cells of the celery stalks are hypertonic to the pure water and
hypotonic to the salt-water
Under what circumstances does membrane transport always require energy?
a. whenever a molecule is polar and is moved through a phospholipid bilayer membrane
b. whenever a solute is charged, such as an ion, and is moved through a phospholipid
bilayer membrane
c. whenever a solute needs to be moved from low concentration to high concentration
through a phospholipid bilayer membrane
d. All of the above - answerc. whenever a solute needs to be moved from low
concentration to high concentration through a
phospholipid bilayer membrane
According to the fluid mosaic model of cell membranes, which of the following is a
TRUE statement about membrane phospholipids?
a. They form a viscous fluid through which proteins shift and flow.
b. They frequently flip-flop from one side of the membrane to the other.
c. They occur in an uninterrupted bilayer, with membrane proteins strictly anchored to
the surface of the membrane.
d. They are free to depart from the membrane and are dissolved in the surrounding
solution.
e. They have hydrophilic tails in the interior of the membrane. - answera. They form a
viscous fluid through which proteins shift and flow.
Which part of the cell is most crucial for getting membrane proteins to their proper
location?
a. Golgi apparatus
b. nucleolus
c. ribosomes
d. lysosome
e. plasma membrane - answera. Golgi apparatus
When a membrane is freeze-fractured, the bilayer splits down the middle between the
two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane,
the bumps seen on the fractured surface of the membrane are
a. integral proteins.
b. ice crystals
c. carbohydrates.
d. platinum
e. cholesterol molecules. - answera. integral proteins.
An animal cell lacking oligosaccharides on the external surface of its plasma membrane
would likely be impaired in which function?
a. cell-cell recognition
b. attaching to the cytoskeleton
c. establishing the diffusion barrier to charged molecules
d. transporting ions against an electrochemical gradient
e. maintaining fluidity of the phospholipid bilaye - answera. cell-cell recognition
Water passes quickly through cell membranes because
a. it is a small, polar, charged molecule.
b. there are hydrophobic channels
c. it moves through aquaporins in the membrane.
d. cells are always hypotonic to their environment
e. the bilayer is amphipathic - answerc. it moves through aquaporins in the membrane.
In order for a protein to be an integral membrane protein it would have to be which of
the following?
a. completely covered with phospholipids
b. amphipathic
c. hydrophilic
d. hydrophobic
e. exposed on only one surface of the membrane - answerb. amphipathic
The transmission of nerve impulses between adjacent nerve cells often requires the
release of a peptide neurotransmitter into the synapse by the process of exocytosis. To
quench the signal, these neurotransmitters are then selectively internalized (taken back
into cells) by a process known as...
a. passive transport
b. phagocytosis
c. receptor-mediated endocytosis
d. signal transduction
e. facilitated diffusion - answerc. receptor-mediated endocytosis
, Celery stalks that are standing in a glass of pure water for several hours become stiff.
Other celery stalks that are standing in a glass of salt-water become limp. From this we
can predict that ....
a. the cells of the celery stalks are hypertonic to the pure water and isotonic to the salt-
water
b. the cells of the celery stalks are isotonic to the pure water and hypertonic to the salt-
water
c. the cells of the celery stalks are hypertonic to both the pure water and to the salt-
water
d. the cells of the celery stalks are hypertonic to the pure water and hypotonic to the
salt-water
e. the cells of the celery stalks are hypotonic to the pure water and hypertonic to the
salt-water - answerd. the cells of the celery stalks are hypertonic to the pure water and
hypotonic to the salt-water
Under what circumstances does membrane transport always require energy?
a. whenever a molecule is polar and is moved through a phospholipid bilayer membrane
b. whenever a solute is charged, such as an ion, and is moved through a phospholipid
bilayer membrane
c. whenever a solute needs to be moved from low concentration to high concentration
through a phospholipid bilayer membrane
d. All of the above - answerc. whenever a solute needs to be moved from low
concentration to high concentration through a
phospholipid bilayer membrane
According to the fluid mosaic model of cell membranes, which of the following is a
TRUE statement about membrane phospholipids?
a. They form a viscous fluid through which proteins shift and flow.
b. They frequently flip-flop from one side of the membrane to the other.
c. They occur in an uninterrupted bilayer, with membrane proteins strictly anchored to
the surface of the membrane.
d. They are free to depart from the membrane and are dissolved in the surrounding
solution.
e. They have hydrophilic tails in the interior of the membrane. - answera. They form a
viscous fluid through which proteins shift and flow.
Which part of the cell is most crucial for getting membrane proteins to their proper
location?
a. Golgi apparatus
b. nucleolus
c. ribosomes
d. lysosome
e. plasma membrane - answera. Golgi apparatus
