Biology 2107/03
Fall 2000
Second Examination
Version A
Name
Be sure to put your name
on the mark-sense sheet as well
Directions:
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Be sure to put your name on the mark-sense sheet and on the exam
booklet. Both must be turned in at the end of the period.
Indicate the correct version letter of your exam in the upper right
corner of the mark-sense sheet in the box marked “KEY ID.”
Each questions has only one correct answer. When a group of choices
is used for more that one question, a choice may be used more than
once.
You may write in the exam booklet, but only the mark-sense sheet will
be graded. No other paper, scratch paper, etc., may be used.
Students must turn in the exam before leaving the room for any
reason. A student may not continue working on the exam after having
left the room.
Multiple Choice. 50 questions, 2 pt each.
The following choices are used for questions 1 – 4.
(a)
(b)
(c)
Microfilaments
Microtubules
Intermediate filaments
1.
These are composed of actin.
2.
These play a major role in maintaining the shape of cells. They also
mediate changes in cell shape, such as in the pseudopods of an
amoeba or the stress fiber attachments of a cell in culture.
3.
These play a major role in the movement of organelles and other
large particles within a cell.
4.
Of the three types of cytoskeletal fibers, this is the only one that is
NOT characterized by the possibility of rapid assembly and
disassembly.
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Page 1
The following diagram shows the structure of phosphatidyl ethanolamine
and applies to questions 5 - 10.
5.
Which of the following best describes the overall structure that is
shown?
(a)
(b)
(c)
Triglyceride
Amino Acid
Cholesterol
6.
Which of the following terms best describes the part labeled “A” in
the diagram?
(a)
(b)
(c)
Fatty acid chain
Amino Acid
Polar head group
7.
Which of the following terms best describes the part labeled “B” in
the diagram?
(a)
(b)
(c)
Fatty acid chain
Amino Acid
Polar head group
8.
Which of the following terms best describes the solubility of this
substance (overall structure) in water?
(a)
(b)
(c)
hydrophobic
hydrophilic
amphipathic
(d)
(e)
(d)
(e)
(d)
(e)
(d)
(e)
Page 2
Phospholipid
Disaccharide
Monosaccharide
Active site
Monosaccharide
Active site
dualistic
multiphasic
9.
This substance is sold in powdered form by chemical supply
houses. If some of the powdered form of this substance were mixed
thoroughly with water, what would happen?
(a)
(b)
The substance would separate from the water and float to the top.
The substance would completely dissolve in the water, making a
uniform solution.
The substance would become chemically oxidized.
The substance would become chemically reduced.
The substance would form microscopic spherical vesicles,
suspended in the water, with the surface of the vesicles made up of
lipid bilayers.
(c)
(d)
(e)
10.
If you wanted to isolate this substance from a cell, where should
you look?
(a)
(b)
(c)
(d)
In
In
In
In
the
the
the
the
plasma membrane
cytoplasm
matrix of the mitochondrion
chromatin of the nucleus.
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11. Some integral membrane proteins have the ability to move. How
would you best characterize this membrane protein mobility?
(a)
(b)
(c)
(d)
(e)
The proteins have free movement in all directions within, across,
and through the membrane (the “free-wheeling” model).
The proteins can move transversely (“flip-flop”) from one side of the
membrane to the other, but they cannot move laterally (side-toside) (the “trans-crystalline” model).
The proteins can move laterally (side-to-side), but they cannot
transversely (“flip-flop”) from one side of the membrane to the other
(the “fluid mosaic” model).
The proteins completely move out of the phospholipid bilayer and
travel through the inside of the cell (through the cytoplasm) until
they reach the phospholipid bilayer on the other side (the “subway
shuttle” model).
The proteins completely move out of the phospholipid bilayer and
travel around the outside of the cell (through the aqueous fluid in
which the cell is suspended) until they reach the phospholipid
bilayer on the other side (the “perimeter bypass” model).
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Page 3
The following choices are used for questions 12 - 15.
(a)
Simple diffusion directly across a phospholipid bilayer
(b)
Facilitated diffusion across a membrane
(c)
Active transport across a membrane
(d)
Both (a) and (b)
(e)
Both (b) and (c)
12.
Small hydrophobic and polar molecules (such as O2, CO2, N2, H2O,
and glycerol) can pass through a membrane by this mechanism,
but larger uncharged polar molecules and ions (such as glucose,
Na+, and K+) cannot pass through a membrane by this mechanism.
13.
This process is almost always mediated by a membrane-bound
carrier protein.
14.
This process requires the expenditure of the cell’s energy, usually
in the form of ATP hydrolysis or energy stored in a concentration
gradient.
15.
In this process, the substance being transported moves from a
high concentration to a low concentration until equilibrium is
reached.
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16. A symport
(a)
(b)
(c)
(d)
(e)
is a channel protein.
is a carrier protein that transports only a single type of solute.
is a carrier protein that transports two different solutes, each from
the same side of the membrane.
is a carrier protein that transports two different solutes, one from
one side of the membrane and one from the other side of the
membrane.
is a synthetic carrier of ions (also known as an ionophore) useful
as a model for ion transport studies.
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17.
What is the function of the Na+-K+ ATPase pump in the plasma
membrane of cells?
(a)
For each cycle in its mechanism, it transports three sodium ions
(Na+) into the cell, two potassium ions (K+) out of the cell, and
hydrolyzes one ATP molecule.
For each cycle in its mechanism, it transports three sodium ions
(Na+) out of the cell, two potassium ions (K+) into of the cell, and
hydrolyzes one ATP molecule.
For each cycle in its mechanism, it transports three sodium ions
(Na+) into the cell, two potassium ions (K+) out of the cell, and
synthesizes one ATP molecule.
For each cycle in its mechanism, it transports three sodium ions
(Na+) out of the cell, two potassium ions (K+) into the cell, and
synthesizes one ATP molecule.
(b)
(c)
(d)
18.
The protein that coats endocytotic vesicles and secretory vesicles is
called
(a)
(b)
(c)
actin
tubulin
porin
19.
Read the following statements about enzyme action:
I.
II.
III.
IV.
V.
(a)
(b)
(c)
(d)
(e)
(d)
(e)
clathrin
laughin
Enzymes are catalysts.
Enzymes significantly change the free energy (G) of a
reaction by changing the final equilibrium concentrations of
the reactants and products.
Enzymes lower the activation energy of a reaction by creating
a stabilized intermediate state known as an “EnzymeSubstrate Complex”
Amino acid side chains in the enzyme do not interact with
the substrate, because the enzyme molecule must be
unchanged at the end of the reaction.
The cell must manufacture a new enzyme molecule for each
substrate molecule that it converts to product (the law of
enzyme-substrate stoichiometry).
Which of the following is correct?
Only statement I is true.
Only statements I, III, and V are true.
Only statements I and III are true.
Only statements I, II, and III are true.
Only statements I, IV, and V are true.
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The following choices are used for questions 20 – 25.
(a)
(b)
(c)
cohabitant
cofactor
coenzyme
(d)
(e)
competitive inhibitor
noncompetitive inhibitor
20.
This is a substance that is chemically similar to the substrate of an
enzyme and can bind to the enzyme’s active site, blocking access
by the substrate.
21.
This is a substance that is not part of the amino acid structure of
an enzyme, but is required for the activity of certain enzymes. This
term specifically refers to a substance that is noncovalently bound
to the enzyme.
22.
This is a substance that is not part of the amino acid structure of
an enzyme, but is required for the activity of certain enzymes. This
term specifically refers to a substance that is covalently bound to
the enzyme.
23.
NAD is an example of this.
24.
Suppose I am studying an enzyme-catalyzed reaction. When I
added a certain substance “XYZ” to the enzyme-substrate mixture,
the reaction stopped. However, when I added more substrate, the
reaction started back again. What type of substance is substance
“XYZ”?
25.
High concentrations of ATP in a cell stop the action of
phosphofructokinase, one of the early enzymes in the glycolytic
pathway. Structural studies have shown that the ATP does not
bind to the active site of the enzyme; instead, it binds to a different
location and changes the conformation of the enzyme. Which of the
terms given above best describes what ATP does to
phosphofructokinase?
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The following choices are used for questions 26 – 31.
(a)
(b)
oxidation
reduction
26.
During glycolysis, NAD is converted into NADH. What has
happened to the NAD?
Page 6
27.
A process in which an atom gains electrons.
28.
This process can occur when an atom becomes bonded to another
atom than is less electronegative.
29.
In biological systems, this process often occurs when an atom
becomes bonded to hydrogen.
30.
Imagine a chemical reaction in which carbon dioxide is converted
into methane (CH4). What has happened to the carbon atom in this
reaction?
31.
During fermentation in human muscle tissue, pyruvic acid is
converted into lactic acid. What has happened to the pyruvic acid
in this process?
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The following choices are used for questions 32 – 34.
(a)
(b)
catabolism
anabolism
32.
This term refers to the processes by which a living organism
obtains its energy and raw materials from nutrients.
33.
Glycolysis and respiration are examples of this type of process.
34.
A synonym for this term is “biosynthesis.”
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The following choices are used for questions 35 - 45.
(a)
(b)
(c)
glycolysis
fermentation
respiration
35.
The final electron acceptor in this process is oxygen (in almost all
organisms)
36.
The final electron acceptor in this process is an acid or alcohol
derived from pyruvic acid.
37.
In the first stage of this process, two ATP are used up (and
converted to ADP).
Page 7
38.
The net yield of ATP in this process is two ATP per molecule of
glucose.
39.
During this process, the carbons of pyruvic acid are completely
oxidized to form three CO2 molecules.
40.
Of the tree processes listed, this one is responsible for synthesis of
the greatest number of ATP.
41.
When fatty acids are converted into acetyl CoA, their carbons are
metabolized by this process.
42.
In this process, electrons are transferred from NADH to pyruvic
acid.
43.
In this process, electrons are transferred from NADH to a series of
electron carriers in the inner mitochondrial membrane.
44.
In this process, electrons are transferred from a three-carbon
intermediate (derived from glucose) to NAD.
45.
A synonym for this pathway is the Embden-Meyerhoff-Parnas
pathway.
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46. During respiration, which of the following processes is most
directly responsible for the synthesis of the greatest amount of
ATP?
(a)
(b)
(c)
(d)
(e)
the
the
the
the
the
47.
The major purpose of fermentation in bacteria and yeast is
(a)
the synthesis of organic acids to regulate the pH of the organism’s
environment.
to provide a means for bacteria to identify each other by the
production of different fermentation end products.
to produce large quantities of ATP from pyruvic acid, since very
little ATP is produced during glycolysis.
to oxidize NADH into NAD.
to regenerate ADP for the process of glycolysis.
(b)
(c)
(d)
(e)
conversion of glucose into pyruvic acid
conversion of pyruvic acid into lactic acid
conversion of pyruvic acid into acetyl CoA and CO2
citric acid (Kreb’s) cycle
respiratory electron transport chain
Page 8
48.
Adenosine triphosphate (ATP) is a good “common currency” of
energy for the cell because
(a)
(d)
(e)
it is highly unstable, breaking down rapidly to provide the cell with
a “boost” of energy.
its G of hydrolysis is about –7.5 kcal/mol, making ATP hydrolysis
a thermodynamically favorable reaction.
the phosphate group that is released during ATP hydrolysis may
become attached to a protein, causing the protein to undergo a
conformational change and to do useful work.
Both (a) and (b) are true.
Both (b) and (c) are true.
49.
Which of the following can affect the fluidity of a membrane?
(a)
(b)
The size of the polar head groups in its phospholipids.
The number of carbon-carbon double bonds in the fatty acid
chains of its phospholipids.
The presence of cholesterol.
More than one of the above.
None of the above.
(b)
(c)
(c)
(d)
(e)
50.
The best term to describe the diffusion of water molecules across a
semipermeable membrane is called
(a)
(b)
(c)
(d)
(e)
pinocytosis
phagocytosis
osmosis
halitosis
active transport
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