Goldfarb D. Biophysics DeMYSTiFied
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322 Biophysics DemystifieD
D.
A and B
E.
B and C
27.
Which property of cdDNA is a topological invariant?
A.
Lk
B.
Tw
C.
Wr
D.
A and B
E.
B and C
28.
Secondary active transport is called secondary because its source of
energy is
A.
an ionic current that was generated by a gated ion channel.
B.
a temperature gradient that was generated by a primary active
transport.
C.
a phospholipid gradient that was generated by secondary
photosynthesis.
D.
a concentration gradient that was generated by a primary active transport.
E.
the second of three pyrophosphate bonds in ATP.
29.
The cell cycle describes
A.
how certain cells with flagella swim in circles to surround their food.
B. the cycle of food entering the cell and being digested, and energy from
that food used to create ATP, which is used to actively transport more
food into the cell (and then the cycle repeats).
C. how cells grow and then divide in daughter cells, which grow and then
divide, and so on.
D. any of a variety of cyclical reactions in the cell, for example, the so-
dium-potassium pump, which has a cycle of repeatedly pumping so-
dium out of the cell and potassium into the cell.
E.
There’s no such thing as the cell cycle. You just made that up.
30.
Which amino acids tend to be on the outside of a folded protein that is
floating around in a cell?
A.
Nonpolar
B.
Uncharged polar
F inal Exam 323
C.
Charged
D.
A and B
E.
B and C
31.
What are the three major divisions of biophysics when categorizing
the branches of biophysics according to size of what is being
studied?
A.
Small, medium and large biophysics
B.
Microscopic, tissue, and organism biophysics
C.
Subcellular, physiological, and environmental biophysics
D.
Subcellular, structural, and macromolecular biophysics
32.
Fill in the blanks: The ultracentrifuge operates on the principle of
__________ and can be used to determine the relative __________ of
molecules.
A.
electrophoresis, size
B.
sedimentation, strengths
C.
centrifugation, elasticity
D.
gravity, compactness
E.
sedimentation, compactness
33.
If we double the number of segments in a freely jointed chain, what is
the effect on the root-mean-square end-to-end distance?
A.
Increase by a factor of 2
B.
Increase by a factor of
2
C.
Decrease by a factor of 2
D.
Decrease by a factor of
2
E.
Remain constant because the average length of each segment will
balance out the change
34.
What do disulfide bonds do?
A.
Provide a favorable Gibbs energy change for bringing together other-
wise distant cysteine residues in a folded protein.
B.
Add rigidity to the folded protein structure.
C.
Form ionic bonds between two charged, sulfur-containing amino
acids.
324 Biophysics De mystifieD
D.
A and B
E.
B and C
35.
How many arrangements are possible given a Boltzmann distribution
for a specific number of molecules and a specific amount of energy?
A.
It depends on how much energy is available.
B.
The average of all possible distributions.
C.
The maximum of all possible distributions.
D.
One.
E.
The answer cannot be determined on the basis of the information given.
36.
An amino acid is a molecule with what functional groups?
A.
An amine and hydrochloric acid
B.
A hydroxyl and an amine
C.
A protein and a polypeptide
D.
A carboxyl and an amine
E.
A hydrogen bond and a dipole
37.
Which of the following is not a membrane-bound organelle?
A.
Mitochondrion
B.
Chloroplast
C.
Vacuole
D.
Ribosome
E.
Nucleus
38.
In an alpha helix
A.
the backbone is on the inside of the helix.
B.
the side chains have dipoles.
C.
the dipoles are every fourth residue.
D.
the hydrogen bonds occur on the alpha residues.
E.
the base pairs are tilted slightly.
39.
Absorption of light is commonly used to measure
S1. conformational transitions.
S2. voltage across a membrane.
S3. ligand binding.
F inal Exam 325
S4. heat capacity.
A.
S1 and S2
B.
S2 and S3
C.
S3 and S
D.
S1 and S3
E.
S2 and S4
40.
Antiparallel strands are found in
A.
mRNA.
B.
phospholipid hydrocarbon chains.
C.
beta sheets.
D.
alpha helices.
E.
lipid bilayers.
41.
Cooperativity is
A.
the occurrence of separate events together in a nonindependent manner.
B.
several proteins cooperating to form a quaternary structure.
C.
the alpha helix and the beta sheet working together to fold a protein.
D.
a series of independent two-state processes.
E.
two cell membranes fusing together.
42.
Sedimentation describes
A.
the process of dead organisms forming layers on the ocean floor.
B.
a type of rock with fossils in it.
C.
the motion of particles in a fluid under the application of a force.
D.
an analytical ultracentrifuge with special optical devices and sensors.
E.
the release of waste from plant cells into the soil.
43.
An analytical ultracentrifuge contains special optical devices and sen-
sors that can track the movement of molecules as they are being centri-
fuged. From this we can learn the
A.
equations of sedimentation.
B.
size and approximate shape of molecules.
C.
Gibbs energy change for moving a molecule through a fluid.
D.
electric field strength required to ionize large proteins.
E.
sequence of DNA.
326 Biophysics De mystifieD
44.
A cell is
A.
a terrorist organization.
B.
a type of phone.
C.
the basic unit of life.
D.
an egg.
E.
a virus.
45.
Which of the following items apply to prokaryotes?
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
46.
Ribosomes are
A.
quaternary structures that contain protein and RNA.
B.
quaternary structures that contain protein and DNA.
C.
tertiary structures that synthesize polypeptides.
D.
tertiary structures that contain protein, DNA, and RNA.
E.
none of the above
47.
What are the major forces that hold membranes together?
A.
Dipole induction and phospholipid stacking
B.
Dispersion forces and hydrogen bonds
C.
Hydrogen bonds and hydrophobic interactions
D.
Hydrophobic interactions and dispersion forces
E.
Peptide bonds and hydrophilic interactions
48.
Which of the following statements is true?
S1. Superhelical DNA requires a force to hold the superhelix in place.
F inal Exam 327
S2. Circular DNA is always superhelical.
S3. A superhelix is a quaternary structure.
S4. Energy stored in the superhelix can be used to unwind the DNA.
A.
S1 and S2
B.
S1 and S3
C.
S1 and S4
D.
S2 and S3
E.
S2 and S4
49.
Which of the following statements about , contour diagrams are true?
S1. and are angles for the bonds in the polypeptide backbone that
can rotate.
S2. Contours are plotted for values of and for which the potential
energy is favorable.
S3. Steric hindrances disallow certain values of and .
A.
S1 and S2
B.
S2 and S3
C.
S1 and S3
D.
S1, S2, and S3
E.
None of the above
50.
The sedimentation force in gel electrophoresis comes from
A.
the sedimentation coefficient.
B.
gravity.
C.
an electric field.
D.
all of the above
E.
none of the above
51.
The process of converting the nucleotide sequence of an mRNA mole-
cule into an amino acid sequence in a polypeptide is called what?
A.
Transport protein synthesis
B.
Transcription
C.
Translation
D.
Transformation
E.
mRNA to amino acid conversion
328 Biophysics De mystifieD
52.
Molecules on the surface of the cell membrane that bind specific out-
side molecules and thereby signal the cell to do something are called
A.
signal proteins.
B.
ribosomes.
C.
receptors.
D.
antennae.
E.
cell walls.
53.
What do the Golgi apparatus and the endoplasmic reticulum have in
common?
A.
They are both folded membranes that provide surface area for bio-
chemical reactions.
B.
They are both part of the endomembrane system.
C.
They are both involved in protein synthesis from amino acids.
D.
A and B
E.
B and C
54.
A major role of lipids is what?
A.
Muscle contraction
B.
Phosphorylation of DNA
C.
Structure of phospholipids
D.
Structure of membranes
E.
Digestion
55.
Carbon atoms usually form how many covalent bonds?
A.
2
B.
4
C.
6
D.
8
E.
10
56.
DNA and RNA are examples of
A.
nucleic acids.
B.
nucleotides.
C.
proteins.
F inal Exam 329
D.
lipids.
E.
topoisomerases.
57.
A beta sheet is
A.
a common tertiary structure in proteins.
B.
two polypeptide strands with their backbones hydrogen bonded
together.
C.
a thin covering on the outside of the cell wall in some organisms.
D.
a common secondary structure in membranes.
E.
a series of flat aromatic molecules connected side to side.
58.
What source of energy does primary active transport use to move mole-
cules through a membrane?
A.
Optical tweezers
B.
Internal pressure
C.
Pyrophosphate bonds
D.
Concentration gradient
E.
Gibbs energy
59.
Polar bonds are
A.
ionic bonds.
B.
covalent bonds in which the electrons are shared unevenly.
C.
stronger than hydrogen bonds.
D.
A and B
E.
B and C
60.
The internal energy that results from a charge-dipole interaction
A.
depends on the angle between the dipole axis and a straight line be-
tween the dipole and the charge.
B.
decreases faster than it does for a charge-charge interaction, as the dis-
tance between the charge and the dipole increases.
C.
increases faster than it does for a charge-charge interaction, as the dis-
tance between the charge and the dipole increases.
D.
A and C
E.
A and B
330 Biophysics De mystifieD
61.
Forces that arise from synchronized fluctuating charge distributions are
classified as
A.
van der Waals forces.
B.
dispersion forces.
C.
synchronization forces.
D.
A and B
E.
B and C
62.
Stacking interactions are most important to which class of biomolecule?
A.
Proteins
B.
Lipids
C.
Nucleic acids
D.
Amino acids
E.
Tryptophan, tyrosine, and phenylalanine
63.
The helical shape of DNA is due primarily to
A.
aromatic side chains.
B.
base stacking.
C.
hydrogen bonds.
D.
van der Waals constant.
64.
Proteins are involved in
A.
DNA synthesis.
B.
enzymatic processes.
C.
lipid metabolism.
D.
all of the above
E.
none of the above
65.
The Gibbs energy change of bringing a hydrophobic molecule in con-
tact with water is unfavorable primarily due to a
A.
large decrease in the hydrophobic molecule’s entropy.
B.
large increase in the hydrophobic molecule’s entropy.
C.
large decrease in the water’s entropy.
D.
large increase in the water’s entropy.
E.
positive Gibbs energy change.
F inal Exam 331
66.
In which of the following does the hydrophobic effect play a role?
A.
Hydration of ions, base stacking, protein folding, and micelle formation
B.
Hydration of ions, base stacking, and micelle formation
C.
Base stacking and protein folding
D.
Protein folding and micelle formation
E.
Hydration of ions and protein folding
67. The energy of steric interactions is
proportional to
A.
1/r.
B.
1/r
2
.
C.
1/r
4
.
D.
1/r
6
.
E.
1/r
12
.
68.
How is statistical mechanics useful in biophysics?
A.
Statistical mechanics provides a molecular interpretation
of experimental observables.
B.
Statistical mechanics allows us to do statistical analysis of the me-
chanical forces on a biological system.
C.
Statistical mechanics provides a thermodynamic
interpretation of biological events.
D.
All of the above
E.
None of the above
69.
How many distributions of 8 units of energy among four molecules are
possible?
A.
1
B.
2
C.
3
D.
4
E.
5
70.
Which distribution shown in Fig. 5-4 is most likely to occur (relative to
the other distributions shown in Fig. 5-4)?
A.
The one with the most permutations
B.
The one with the most molecules