Goldfarb D. Biophysics DeMYSTiFied
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332 Biophysics DemystifieD
C.
The one with the maximum energy available
D.
The one with the most distributions
E.
None of the above
71.
Given the following two expressions for the partition function
Ze Ze
A
j
NStates
Bi
i
L
E
j
kT
E
i
kT
==
−
=
−
=
∑∑
11
and
MAX
ω
which of the following statements is not true?
A.
In Z
A
, each E
j
is a different state; In Z
B
, each E
i
is a different energy
level.
B. v
i
is the degeneracy of energy E
i
.
C.
The value of Z
B
will be larger than the value of Z
A
because each
term is multiplied by
v
i
.
D.
Whether you use Z
A
or Z
B
is just a matter of which is mathemati-
cally more convenient for the particular statistical mechanical model
at hand.
E.
If you use Z
B
, no two E
i
will have the same value, but if you use
Z
A
, it is possible that some of the E
j
will have the same value as
other E
j
.
72.
The sodium-calcium exchanger, a membrane transport protein that
moves three Na
+
ions into the cell for every Ca
2+
ion that it moves out
of the cell, is an example of
A.
inefficient use of sodium.
B.
secondary active transport.
C.
primary active transport.
D.
passive ion channels.
E.
the need for calcium to build strong bones.
73.
The patch clamp is a technique used in
A.
electrophoresis.
B.
electrophysiology.
C.
X-ray crystallography.
D.
optical tweezers.
E.
analytical ultracentrifugation.
F inal Exam 333
74.
A 225-lb firefighter climbs a ladder straight up to the ninth floor (36 m).
Assuming the only energy required to do this is the energy needed to
lift the firefighter’s weight to the ninth floor, how much energy must
the firefighter expend in climbing the ladder?
A.
36 kcal
B.
1800 J
C.
3600 kJ
D.
36 kJ
E.
3.6 kJ
75.
An increase in entropy
A.
requires energy input to the system.
B.
contributes to an unfavorable Gibbs energy change.
C.
was invented by Rudolf Clausius.
D.
contributes to reducing the Gibbs energy.
E.
explains why living systems can ignore the second law of
thermodynamics.
76.
Liposomes made from a certain type of phospholipid melt at 310 K. At
the melting temperature the Gibbs energy change is zero. The enthalpy
change for the lipid phase transition is 62 kcal/mol. What is the
entropy change? Hint: Use Eq. (4-14).
A.
200 cal/degree/mol
B.
2000 cal/degree/mol
C.
2 kcal/degree/mol
D.
200 kcal/degree/mol
E.
22 kcal/degree/mol
77.
Liposomes made from a certain type of phospholipid melt at 310 K.
At the melting temperature, the Gibbs energy change is zero. The
enthalpy change for the lipid phase transition is 31 kcal/mol. As-
suming that the enthalpy change and the entropy change are the
same at 320 K as they are at 310 K, what is the Gibbs energy
change at 320 K? Hint: You need to first calculate the entropy
change; use Eq. (4-14).
A.
210 kcal/mol
B.
220 kcal/mol
334 Biophysics DemystifieD
C.
21 kcal/mol
D.
11 kcal/mol
E.
110 kcal/mol
78.
Which of the following statements is true?
S1. Secondary structure is two dimensional, whereas tertiary structure is
three dimensional.
S2. Primary structure is one dimensional, specifying only the sequence in
which atoms or groups of atoms are connected to one another.
S3. Biological molecules are always polymers.
S4. Residues are the parts of a molecule left behind after the molecule
separates from its parent molecule.
S5. Quaternary structure takes into account time as well as three dimen-
sions in space.
A.
S1, S2, S3, and S4
B.
S2, S3, S4, and S5
C.
S3
D.
S2
E.
None of the above
79.
Enthalpy is internal energy plus
A.
pressure times volume.
B.
entropy.
C.
temperature times entropy.
D.
volume times temperature.
E.
Gibbs energy.
80.
Which of the following is true?
S1. Membrane protein structure is inside out relative to cytoplasmic
proteins.
S2. Positive charges on charged amino acid side chains can participate in
cation-pi interactions with aromatic amino acid side chains.
S3. Aromatic side chains are most likely to hydrogen bond with
water.
F inal Exam 335
S4. A lower potential energy means the conformation is more stable.
A.
S1, S2, and S3
B.
S1, S2, and S4
C.
S2, S3, and S4
D.
S1, S3, and S4
E.
None of the above
81.
Eight units of energy are distributed among five molecules as follows:
three molecules with 1 unit of energy each; one molecule with 2 units
of energy; one molecule with 3 units of energy. How many ways are
there to arrange the molecules in the same distribution?
A.
5
B.
10
C.
15
D.
20
E.
25
82.
If we use the Gibbs energy change to evaluate a biophysical process, we
can effectively ignore the second law of thermodynamics because
A.
the second law is irrelevant to biological systems.
B.
the second law only applies when entropy is increasing.
C.
an increase in entropy is favorable for the Gibbs energy change.
D.
the second law is built into the formula for Gibbs energy.
E.
Gibbs was able to show that the second law no longer applies nowa-
days.
83.
What do the two-state approximation and the nearest-neighbor approx-
imation have in common?
A.
They are both observed in DNA.
B.
They are both intermediate steps in calculating the partition
function.
C.
Nearest neighbors can only assume two states between them.
D.
All of the above
E.
None of the above
336 Biophysics DemystifieD
84.
Unsaturated lipids are
A.
lipids containing double bonds within the hydrocarbon chain.
B.
lipids that are not saturated with hydrogen.
C.
lipids that cannot pack as closely together as saturated lipids.
D.
all of the above
E.
none of the above
85.
A certain receptor on the cell surface binds the hormone insulin with
a Gibbs energy change of 212.5 kcal at body temperature (310 K).
Using a calorimeter, the binding enthalpy change was measured to be
290 kcal. Calculate the entropy change for insulin binding to
the receptor.
A.
20.1 kcal/degree
B.
20.75 kcal/degree
C.
20.25 kcal/degree
D.
20.025 kcal/degree
E.
277.5 kcal/degree
86.
What is special about pi electrons in aromatic rings?
A.
Each electron contains an internal energy of 3.141593 3 10
220
J.
B.
These elections are called cations because they participate in
cation-pi interactions.
C.
Pi electrons are delocalized in aromatic rings
D.
They form the circumference of the aromatic ring, which is 2 times
p times the radius of the ring.
E.
Nothing (this is a trick question; aromatic rings do not contain
pi electrons).
87.
Electromagnetic spectroscopy typically measures some property of the
EM radiation, such as the amount of radiation that is
A.
scattered.
B.
absorbed.
C.
radioactive.
D.
A and B
E.
B and C
F inal Exam 337
88.
Natural DNA sequences are
A.
homogenous.
B.
homozygous.
C.
heterozygous.
D.
heterogeneous.
E.
herbivorous.
89.
Which technique can be used to separate molecules both according to
size and according to electric charge?
A.
Gel electrophoresis
B.
Atomic force microscopy
C.
Ionization centrifugation
D.
Calorimetry
E.
Mass electrophoresis
90.
The peptide bond
A.
links amino acids together.
B.
can be treated as a dipole with D 5 0.7.
C.
is surrounded on both sides by polar bonds.
D.
all of the above
E.
none of the above
91.
In proteins, hydrogen bonds can form directly between various amino
acid side chains and other amino acid side chains, or they can form
between amino acid side chains and water. The Gibbs energy differ-
ence between these two types of hydrogen bonds is small. This fact
tells us that
A.
it is easy to form hydrogen bonds in proteins.
B.
amino acid side chains are not very good at forming hydrogen
bonds.
C.
many hydrogen bonds are needed to add up to a significant Gibbs
energy change.
D.
polar amino acids are an important dietary nutrient.
E.
hydrogen bonding plays a relatively minor role in stabilizing protein
structure.
338 Biophysics DemystifieD
92.
A favorable Gibbs energy change
A.
means that the Gibbs energy of the system has decreased.
B.
will drive a process forward.
C.
is negative.
D.
all of the above
E.
none of the above
93.
What effect does the presence of cholesterol in a bilayer have on the
movement of phospholipids in the plane of the bilayer?
A.
It causes them to move in a straight line.
B.
It prevents them from moving at all.
C.
It creates steric restrictions on phospholipid movement within the
fluid mosaic.
D.
All of the above
E.
None of the above
94.
A change in the shape of a biomolecule is called a
A.
conformational transition.
B.
topological transition.
C.
phase transition.
D.
transitional configuration.
E.
configurational alignment.
95.
Which has the largest influence on stabilizing protein structure?
A.
Zwitterions
B.
Hydrophilic dipoles
C.
Hydrophobic forces
D.
Hydrogen bonds
96.
When a membrane protein folds into its native state,
A.
all of the polar amino acid side chains are removed.
B.
nonpolar side chains are on the inside, away from the aqueous
environment.
C.
there is a favorable Gibbs energy change for moving the nonpolar
side chains to the inside.
D.
hydrophobic portions of the molecule will be on the outside.
E.
the protein will denature rapidly.
F inal Exam 339
97.
When the double helix of a closed duplex DNA unwinds,
A.
Tw increases and Wr increases.
B.
Tw decreases and Wr decreases.
C.
Tw increases and Wr decreases.
D.
Tw decreases and Wr increases.
E.
Tw and Wr remain constant.
98.
Which of the following items apply to eukaryotes?
S1. Typically larger
S2. Typically smaller
S3. Membrane-bound organelles
S4. Shorter cell cycle (rapid division)
S5. Simpler biochemical reactions
A.
S1 and S3
B.
S2 and S4
C.
S1 and S4
D.
S2 and S3
E.
S2, S4, and S5
99.
If a dipole is allowed to rotate freely in solution, what technique is used
to calculate the interaction energy?
A.
Circular dichroism
B.
Rotational symmetry
C.
Angular averaging
D.
Thermal averaging
E.
Rotational averaging
100.
What does the cytoskeleton do?
A.
Supports skin and muscle cells
B.
Adds support to help the cell maintain its shape
C.
Is involved in transporting molecules from one location in the cell to
another
D.
A and B
E.
B and C
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341
Answers to Quizzes
and Final Exam
chapter 1
1. C
2. D
3. A
4. D
5. D
6. C
7. D
8. A
chapter 2
1. C
2. D
3. B
4. D
5. C
6. A
7. D
8. D
9. D
10. C
chapter 3
1. C
2. A
3. C
4. C
5. C
6. C
7. B
8. D
9. C
10. B
chapter 4
1. C
2. A
3. D
4. C
5. B
6. D
7. D
8. D
9. B
10. A
chapter 5
1. D
2. B
3. A
4. D
5. B
6. A
7. D
8. D
9. A
10. C
chapter 6
1. C
2. C
3. E
4. B
5. D
6. D
7. C
8. A
9. E
10. A
chapter 7
1. B
2. C
3. D
4. B
5. D
6. A
7. A
8. B
9. D
10. D
chapter 8
1. D
2. A
3. D
4. B
5. B
6. C
7. D
8. C
9. C
10. G