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Chapter 7 Online Questions



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

Which of the following types of molecules are the major structural components of the cell membrane?
a.
phospholipids and cellulose
b.
nucleic acids and proteins
c.
phospholipids and proteins
d.
proteins and cellulose
e.
glycoproteins and cholesterol
 

 2. 

When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that
a.
the integral membrane proteins are not strong enough to hold the bilayer together.
b.
water that is present in the middle of the bilayer freezes and is easily fractured.
c.
hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.
d.
the carbon-carbon bonds of the phospholipid tails are easily broken.
e.
the hydrophobic interactions that hold the membrane together are weakest at this point.
 

 3. 

The lateral mobility (fluidity) of lipids and proteins in membranes is a consequence of
a.
lack of covalent bonds between the lipid and protein components of the membrane.
b.
weak hydrophobic interactions among the components in the interior of the membrane.
c.
the presence of liquid water in the interior of the membrane.
d.
A and B only
e.
A, B, and C
 

 4. 

What is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
a.
by increasing the percentage of unsaturated phospholipids in the membrane
b.
by increasing the percentage of cholesterol molecules in the membrane
c.
by decreasing the number of hydrophobic proteins in the membrane
d.
A and B only
e.
A, B, and C
 

 5. 

All of the following are functions of integral membrane proteins except
a.
protein synthesis.
b.
active transport.
c.
hormone reception.
d.
cell adhesion.
e.
cytoskeleton attachment.
 

 6. 

Which of the following is correct about integral membrane proteins?
a.
They lack tertiary structure.
b.
They are loosely bound to the surface of the bilayer.
c.
They are usually transmembrane proteins.
d.
They are not mobile within the bilayer.
e.
They serve only a structural role in membranes.
 

 7. 

What membrane-surface molecules are thought to be most important as cells recognize each other?
a.
phospholipids
b.
integral proteins
c.
peripheral proteins
d.
cholesterol
e.
glycoproteins
 

 8. 

Which of the following adheres to the extracellular surface of animal cell plasma membranes?
a.
fibers of the extracellular matrix
b.
fibers of the cytoskeleton
c.
the phospholipid bilayer
d.
cholesterol
e.
carrier proteins
 

 9. 

After a membrane freezes and then thaws, it often becomes leaky to solutes. The most reasonable explanation for this is that
a.
transport proteins become nonfunctional during freezing.
b.
the lipid bilayer loses its fluidity when it freezes.
c.
aquaporins can no longer function after freezing.
d.
the integrity of the lipid bilayer is broken when the membrane freezes.
e.
the solubility of most solutes in the cytoplasm decreases on freezing.
 

 10. 

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
a.
CO2
b.
an amino acid
c.
glucose
d.
K+
e.
starch
 

 11. 

Water passes quickly through cell membranes because
a.
the bilayer is hydrophilic.
b.
it moves through hydrophobic channels.
c.
water movement is tied to ATP hydrolysis.
d.
it is a small, polar, charged molecule.
e.
it moves through aquaporins in the membrane.
 
 
Use the diagram of the U-tube in the figure below to answer the following questions.

The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half filled with a solution of 2 M sucrose and 1 M glucose. Side B is half filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.
chpt07_files/i0130000.jpg
 

 12. 

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?
a.
It will have no unfavorable effect as long as the water is free of viruses and bacteria.
b.
The patient's red blood cells will shrivel up because the blood fluid is hypotonic compared to the cells.
c.
The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
d.
The patient's red blood cells will shrivel up because the blood fluid is hypertonic compared to the cells.
e.
The patient's red blood cells will burst because the blood fluid is hypertonic compared to the cells.
 
 
Use the figure below to answer the following questions.

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.
chpt07_files/i0150000.jpg
 

 13. 

At the beginning of the experiment,
a.
side A is hypertonic to side B.
b.
side A is hypotonic to side B.
c.
side A is isotonic to side B.
d.
side A is hypertonic to side B with respect to glucose.
e.
side A is hypotonic to side B with respect to sodium chloride.
 

 14. 

If you examine side A after 3 days, you should find
a.
a decrease in the concentration of NaCl and glucose and an increase in the water level.
b.
a decrease in the concentration of NaCl, an increase in water level, and no change in the concentration of glucose.
c.
no net change in the system.
d.
a decrease in the concentration of NaCl and a decrease in the water level.
e.
no change in the concentration of NaCl and glucose and an increase in the water level.
 

 15. 

All of the following membrane activities require energy from ATP hydrolysis except
a.
facilitated diffusion.
b.
active transport.
c.
Na+ ions moving out of the cell.
d.
proton pumps.
e.
translocation of potassium into a cell.
 

 16. 

The main difference(s) between facilitated diffusion and active transport is (are)
a.
facilitated diffusion moves substances down their concentration gradient and active transport moves them against their gradient.
b.
facilitated diffusion does not rely on cellular energy and active transport does.
c.
facilitated diffusion uses channel or carrier proteins and active transport does not.
d.
A and B only
e.
A, B, and C
 

 17. 

Which of the following statements about membrane structure and function is false?
a.
Diffusion of gases is faster in air than across membranes.
b.
Diffusion, osmosis, and facilitated diffusion do not require any direct energy input from the cell.
c.
The types of proteins that are exposed on one side of a membrane are nearly identical to those exposed on the other side of the membrane.
d.
Voltage across the membrane depends on an unequal distribution of ions across the plasma membrane.
e.
Special membrane proteins can cotransport two solutes by coupling diffusion down a concentration gradient to transport against the concentration gradient.
 

 18. 

The membrane activity most nearly opposite to exocytosis is
a.
plasmolysis.
b.
osmosis.
c.
facilitated diffusion.
d.
phagocytosis.
e.
active transport.
 



 
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