BIO250Y1Y April Exam 2003
Answers:
1-C
11-A
21-D
31-D
41-B
51-A
61-D
2-A
12-A
22-E
32-B
42-D
52-C
62-D
3-E
13-C
23-C
33-D
43-B
53-A
63-C
4-A
14-C
24-ABCDE** 34-B
44-A
54-A
64-ABCDE**
5-D
15-D
25-B
35-B
45-A
55-D
65-E
6-B
16-B
26-C
36-B
46-A
56-B
66-C
7-B
17-C
27-B
37-D
47-D
57-A
67-B
8-D
18-E
28-B
38-B
48-D
58-D
68-A
9-C
19-B
29-B
39-ABCDE** 49-A
59-B
69-C
10-E 20-A + B* 30-A
40-B
50-D
60-E
70-D
*Question 20 both A and B were accepted as right answers, see bottom of question
20 for explanation.
** These questions were not marked wrong. Please see their corresponding
questions below for details.
The following questions 1 through 25 are based on Section 3 lectures:
1. Which statement is INCORRECT?
a) Different types of cells in a eukaryotic organism can have different numbers of
cellular structures, depending on the cell’s function.
b) Photosynthetic prokaryotic cells have internal membranes.
c) Gram negative bacteria have two plasma membranes and no cell wall; gram positive
bacteria have one plasma membrane and a cell wall.
d) All prokaryotic and eukaryotic cells have a plasma membrane that controls which
organic molecules and ions can enter the cell.
e) The restriction of biochemical processes into membrane-bound compartments allow
eukaryotic cells to grow larger than prokaryotic cells because, if prokaryotic cells
get too big, diffusion does not occur fast enough for interacting molecules to “find”
each other efficiently.
2. Which statement is CORRECT?
a) Plant cells do not contain intermediate filaments.
b) Plant cells differ from animal cells because they do not have mitochondria.
c) Centrioles are found in the cells of multicellular plants and animals.
d) Plasmodesmata and gap junctions are identical in structure but are given different
names because they occur in plants or animals, respectively.
e) In eukaryotic cells, the endoplasmic reticulum is connected to the plasma
membrane.
3. Which statement is FALSE?
a) Phospholipids, glycolipids, and sphingomyelin are all polar lipids found in natural
membranes.
b) Plant membranes contain more types of steroids than do animal membranes.
c) Most membrane components are amphipathic.
d) Different membranes may contain different types and proportions of polar lipids.
e) Peripheral proteins are covalently bound to the surface of a membrane.
4. A scientist purified a protein from animal cells and made fluorescent antibodies to it.
When she isolated pieces of the plasma membrane from another batch of animal cells
and added the fluorescent antibodies, she could see fluorescence on only one side of
the membrane using a fluorescence microscope. She then took some fresh pieces of
plasma membrane and suspended them in a salt solution before adding the fluorescent
antibodies. The plasma membrane did not become fluorescent.
The protein was most likely:
a) a peripheral protein.
b) a receptor protein.
c) a glycosylphosphatidylinositol-anchored protein.
d) a cytosolic protein.
e) a transmembrane protein.
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Continued…
5. Which statement is CORRECT?
The phase transition temperature of an artificial lipid bilayer can be increased by:
a) decreasing the length of the fatty acyl chains.
b) decreasing the numbers of transmembrane proteins.
c) changing the type of steroids.
d) decreasing the frequency of unsaturated fatty acyl chains.
e) decreasing the frequency of lipid-anchored proteins.
6. Which statement is CORRECT?
a) In artificial lipid bilayers, flip-flop of lipid molecules is very fast.
b) In artificial lipid bilayers, added proteins often move laterally faster than they do in
natural membranes.
c) Proteins never flip-flop in natural membranes but they may flip-flop in artificial
lipid bilayers.
d) Lateral movement of proteins in natural membranes may be increased by
attachment to the cytoskeleton.
e) Because the flip-flop of lipids is fast in the endoplasmic reticulum, the two leaflets
of natural membranes always identical in the frequency and type of polar lipids.
7. Which of the following is an example of ACTIVE TRANSPORT?
a) The movement of calcium through a receptor ion channel.
b) The movement of calcium through a calcium/proton antiporter.
c) The movement of water across the plant plasma membrane.
d) The movement of glucose through a uniporter.
e) The movement of isopropanol across an erythrocyte plasma membrane.
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Continued…
8. A scientist transformed a plant with a gene for a cytoplasmic protein that fluoresced
when it bound a calcium ion. He then tried to push a very small needle into an
epidermal cell while he watched it under the microscope. As he tried to insert the
needle, there was a rapid increase in fluorescence of the cell. What type of ion
channel protein was most likely to be responsible for this response?
a) Resting.
b) Ligand gated.
c) Voltage gated.
d) Stretch-activated.
e) Aquaporins.
9. Which of the following is an example of PASSIVE DIFFUSION?
a) The movement of protons through an F-class ATPase.
b) The movement of nitrate ions into the plant vacuole.
c) The movement of oxygen across a membrane.
d) The movement of protons across a plant plasma membrane.
e) The movement of glucose through the sodium/glucose symporter.
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Continued…
10.Which statement is the BEST ANSWER?
If a transporter in the plasma membrane has a high affinity for the molecule that it
transports, and the cell has a very low cytosolic level of the molecule, then:
a) the transport rate increases linearly, with no limit, as the external concentration of
the molecule increases.
b) the transport rate increases very slowly as the external concentration of the
molecule increases.
c) the transport rate is not affected by the external concentration of the molecule.
d) the transporter binds tightly to the molecule, which slows the rate of uptake of the
molecule into the cell.
e) Half the maximum transport rate is reached at a low external concentration of the
molecule.
11. Which statement is FALSE?
a) P-Class ATP-powered pumps are found only in the plasma membrane.
b) V-Class ATP-powered pumps are not phosphorylated during the transport process.
c) The ABC superfamily of transport proteins includes members that transport a
variety of drugs out of mammalian cells.
d) V-Class and F-Class ATPases have subunits that have sequence homology.
e) During the synthesis of ATP by F-Class ATPases, protons flow though the
transport protein from the exoplasmic face to the cytosolic face.
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Continued…
12. Which of the following processes involve a proton motive force?
1. The release of glucose from an animal intestinal epithelial cell into the
bloodstream.
2. The uptake of amino acids into a plant cell.
3. The uptake of sucrose into the plant vacuole.
4. The uptake of calcium into the sarcoplasmic reticulum.
5. The uptake of glucose into a red blood cell.
6. The synthesis of ATP in the mitochondrion.
a) 2, 3, 6.
b) 3, 4, 6.
c) 2, 3, 4.
d) 1, 2, 6.
e) 1, 3, 5.
13. Which of the following vesicles have a clathrin coat when they are first formed?
a) Transport vesicles that form from the endoplasmic reticulum.
b) Vesicles that form from the cis-Golgi reticulum and travel to the endoplasmic
reticulum.
c) Transport vesicles that take lysosomal enzymes from the trans –Golgi reticulum.
d) Vesicles involved in constitutive secretion from the trans –Golgi reticulum.
e) Vesicles that form from the medial-Golgi cisterna.
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Continued…
14. Which statement is FALSE?
During receptor-mediated endocytosis of LDL particles:
a) only certain transmembrane proteins bind to assembly particles and get taken up in
coated vesicles.
b) the protein coat has to be removed from the vesicle before the vesicle can fuse with
the sorting vesicle.
c) the low proton concentration in the sorting vesicle causes the LDL particle to
become separated from its receptor.
d) the LDL receptors are sent back to the plasma membrane in the membrane of
vesicles that fuse with the plasma membrane.
e) the LDL particles travel by vesicles from the sorting vesicle to the lysosome, where
they are broken down by lysosomal enzymes.
15. Which statement is FALSE?
a) When a vesicle fuses with its target membrane, the V-snares are gathered into a
vesicle membrane which buds off the target membrane to prevent the target
membrane from accumulating V-snare proteins.
b) When a vesicle fuses with its target membrane, the cytosolic face of the vesicle
membrane becomes the cytosolic face of the target membrane.
c) In eukaryotic cells, new membranes are made by the extension of existing
membranes.
d) Phospholipid synthesis occurs on the exoplasmic face of the endoplasmic
reticulum.
e) Phospholipids are distributed from the endoplasmic reticulum to the Golgi by
vesicle transport.
.
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Continued…
16. During the synthesis of secretory proteins the following events happen:
1. the signal sequence is translated.
2. the two subunits of a cytosolic ribosome binds to the mRNA.
3. protein synthesis stops.
4. the signal recognition particle (SRP) binds to the signal sequence.
5 the ribosome and protein are transferred to a translocon.
6. the secretory protein folds.
7. the SRP binds to its receptor in the ER (endoplasmic reticulum) membrane.
8. the signal sequence is cleaved by a signal peptidase.
The correct order for these events is:
a) 1, 2, 3, 4, 7, 5, 8, 6.
b) 2, 1, 4, 3, 7, 5, 8, 6.
c) 2, 1, 4, 3. 5, 8, 7, 6.
d) 1, 2, 4, 3, 5, 8, 7, 6.
e) 2, 1, 3, 4, 8, 5, 7, 6.
17. Which statement is FALSE?
a) Transmembrane proteins may have their N-terminus on either the cytosolic or the
exoplasmic face of a membrane.
b) Proteins that will become GPI-anchored proteins have a stop-transfer membraneanchor sequence coded for by their mRNA.
c) In the case of proteins that span the membrane several times, the signal recognition
particle receptor is involved in the insertion into the membrane of each “loop” of
the protein.
d) Transmembrane proteins may be receptors, transport proteins or enzymes.
e) Secretory proteins do not have stop-transfer membrane-anchor sequences.
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Continued…
18. Which statement is CORRECT?
a) O-linked and N-linked oligosaccharides are added to a protein after the
oligosaccharide is completed.
b) The oligosaccharides of all glycoproteins are made partly on the cytoplasmic face
of the ER membrane and partly on the exoplasmic face.
c) Sugars of O-linked oligosaccharides are added to the protein only in the ER.
d) The N-linked oligosaccharide is added to an aspartic acid of the protein when the
aspartic acid is part of a sequence, Aspartic acid –Serine (or threonine).
e) Processing of the N-linked oligosaccharide begins in the endoplasmic reticulum.
19. In the cisternal progression hypothesis of the movement of lumen and
membrane proteins through the Golgi complex, which statement is FALSE?
a) The trans-Golgi reticulum breaks up to form vesicles that fuse with the plasma
membrane or the lysosome.
b) Transport vesicles containing secretory proteins from the trans-Golgi compartment
fuse with the previous medial-Golgi compartment.
c) The medial-Golgi compartment becomes the new trans-Golgi compartment.
d) Transport vesicles from the ER fuse to form the cis-Golgi reticulum.
e) Three different coat proteins are involved in vesicle movement to and from the
Golgi compartments.
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Continued…
20. A scientist grew some plant cells in a liquid culture medium and noticed that when he
added a large, water-soluble, macromolecule solution to the cell culture, the pH of the
medium decreased rapidly. Which of the following is the most likely explanation
for these observations?
a) The chemical inhibited the action of a proton ATPase in the plasma membrane.
b) The chemical inhibited the action of a proton symporter in the plasma membrane.
c) The chemical inhibited the action of an F-Class ATPase.
d) The chemical activated a calcium ion channel in the plasma membrane.
e) The chemical inhibited the action of a potassium resting channel.
The explanation “a” is the best and most likely reason for the observation and would be
the fastest mechanism for the observed results—notice the comment saying the pH of the
medium decreased rapidly. However, we also allowed explanation “b” because the
chemical might have inhibited the action of a proton symporter, but this inhibition would
have been slower.
21. Which of the following steps in the hormone-triggered breakdown of glucose in
liver cells involves an amplification of the signal?
1. The activation of the receptor by the ligand (hormone).
2. The activation of G protein by the receptor.
3. The activation of adenylyl cyclase.
4. The synthesis of cAMP by adenylyl cyclase.
5. The activation of cAMP-dependent protein kinase (cAPK) (=protein kinase A) by
cAMP.
6. The activation of glycogen phosphorylase kinase by cAPK.
a) 1, 2, 3, 4, 6.
b) 1, 3, 6.
c) 3, 4, 5.
d) 2, 4, 6.
e) 1, 4, 6
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Continued…
22. Which of the following events does NOT involve GTP-binding proteins?
a) The fusion of a vesicle with a target membrane.
b) The Ras signalling pathway.
c) The synthesis of secretory proteins.
d) The hormone-activation of phospholipase C.
e) The hormone-activation of a tyrosine kinase-linked receptor.
23. A scientist mutated animal cells so that a group of amino acids in a particular protein
were changed. The protein in normal cells was not secreted, and when the scientist
applied fluorescently-labeled antibodies to the protein to fixed sections of the normal
animal cell, small membrane-bound structures in the cytoplasm became fluorescent.
In the mutant cells, the protein was secreted into the culture medium and the cells
started to die. Which statement best explains these results?
a) The changed amino acids were part of the signal sequence.
b) The changed amino acids were part of a stop-transfer membrane anchor sequence.
c) The changed amino acids prevent the attachment of N-linked oligosaccharides to
the protein.
d) The changed protein was a signal peptidase.
e) The changed amino acids were part of a KDEL sequence.
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Continued…
24. The original wording of this question was ambiguous and therefore not marked
wrong on the April 2003 exam. See the corrected version of the questions below:
A scientist mutated a gene in some animal cells. When he added a hormone to the
normal cells, there was an increase in glycogen breakdown that was partly inhibited
by staurosporine(an inhibitor of some protein kinases), and partly inhibited by an
inhibitor of gene transcription. In the mutant cells, the hormone induced a lower level
of glycogen breakdown than in wildtype cells and this breakdown was totally
inhibited by staurosporine. Which of the following is most likely to be correct?
a) The mutation is in glycogen phosphorylase kinase.
b) The mutation is in a cAMP-dependent protein kinase.
c) The mutation is in the hormone receptor.
d) The mutated protein is a transcription factor.
e) The mutated protein is a MAPkinase.
25. You are a summer student hired by a lab doing research on signal transduction in
animal cells. You are asked to design ONE simple preliminary experiment to test
whether the IP3 signaling pathway is involved in the response to water-soluble
hormone X. The lab does not have the equipment to measure IP3 directly. Of the
choices below, which is the best experiment to choose (i.e. the one with the least
possible number of interpretations of the results)?
a) Measure the change in calcium level in the cell cytosol after hormone treatment.
b) Treat the cell with a “blocker” of ion channels in the endoplasmic reticulum and
then measure the change in calcium level in the cell cytosol after hormone
treatment.
c) Add a calcium-binding chemical of high molecular mass to the cell culture medium
and then check whether the cells still respond to the hormone.
d) Measure the amount of phospholipase C in the cell before and after hormone
treatment.
e) Measure the level of protein kinase activity in the cell before and after hormone
treatment.
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The following questions 26 through 50 are based on Section 4 lectures:
26. The uniform distribution of melanosome vesicles in fish melanophores is
promoted by:
a) dynein.
b) kinesin.
c) myosin.
d) treadmilling.
27. What process is likely to be affected by incubating an actin-myosin gel with
AMPPCP, a non-hydrolysable form of ATP?
a) The binding the myosin head to the thin filaments.
b) The displacement of the myosin head towards the Z-line.
c) The binding of calcium to the troponin regulatory subunit.
d) Rigor mortis will be prolonged.
28. Binding of profilin to the phospholipid phosphoinositol 4,5-bisphosphaste
(PIP2):
a) promotes polymerization of actin near the cell cortex.
b) inhibits binding of G-actin to profilin.
c) prevents binding of VASP to G-actin.
d) prevents capping of F-actin near the plasma membrane.
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Continued…
29. Injecting thymosin β4 into fibroblast cells causes:
a) polymerization of F-actin.
b) depolymerization of F-actin.
c) an increase in the affinity of profilin for G-actin.
d) a sequestration of G-actin into an active form.
30. Which of the following actin binding proteins is associated with cytokinesis:
a) Myosin II.
b) Myosin V.
c) Dynein.
d) Cadherins.
31. Dictyostelium cells lacking myosin I:
a) fail to form filopodia.
b) cannot from focal adhesion sites.
c) have enhanced stress-fiber assembly.
d) have a poor sense of direction in response to chemotactic agents.
32. In vitro, a “lag-period” is observed before actin polymerization occurs because:
a) hydrolysis of ATP by G-actin is delayed in the absence of profilin.
b) the formation of G-actin trimers is very slow.
c) addition of G-actin to trimers is slower than dimers.
d) a large amount of F-actin needs to made to increase the viscosity of the solution.
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Continued…
33. Which of the following are you LEAST LIKELY to use as a reagent to
determine the orientation of F-actin in a sliding filament assay?
a) Fluorescently-labelled CapZ.
b) Fluorescently-labelled tropomodulin.
c) S1 fragments.
d) Fluorescently-labelled G-actin.
34. The diversity of myosin interactions with other cellular components is
determined by:
a) regulatory chains.
b) the tail domain.
c) the actin-binding domain.
d) the light chains.
35. Fibroblast binding to the underlying ECM could be decreased by the addition of
which of the following reagents to the culture medium?
a) Anti-myosin II antibodies.
b) Disintegrins.
c) Anti-actin antibodies.
d) Fibronectin.
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Continued…
36. Injection of G-actin tagged with caged-fluorescent dyes allows researchers to
examine F-actin polymerization in vivo. Intense fluorescence is generated by
photoactivating the caged fluorescent dye with UV-irradiation. In migrating cells,
the change in the position of the fluorescence image shortly after
photoactivation indicates:
a) the rate of migration varies over time.
b) polymerization is occurring at the leading edge.
c) cortical F-actin polymerization is decreased by UV-irradiation.
d) the G-actin concentration varies in the cytosol.
37. Non-junctional cell adhesion is associated with:
a) fibroblast cells.
b) epithelial cells.
c) basal surfaces of epitheal cells.
d) all of the above.
38. At which point in the assembly of intermediate filament assembly is polarity
LOST?
a) dimer formation.
b) tetramer formation.
c) protofilament assembly.
d) protofibril assembly.
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Continued…
39. This question was not mark wrong because statement #4 should read “Mutations in
keratin cause epidermolysi bullosa simplex (not desmin)”. Therefore the correct
answer should have been C (2 and 4).
With respect to intermediate filaments, which of the following statements ARE
TRUE?
1. Dimers can only be formed between identical monomers.
2. Intermediate filaments are more stable and flexible than microtubules.
3. Intermediate filaments are sandwiched between microfilaments and microtubules.
4. Mutations in desmin cause epidermolysis bullosa simplex.
a) 1 and 2.
b) 2 and 3.
c) 2 and 4.
d) 1 and 4.
40. You have treated melanophores grown in tissue culture with nocodozole. Which of
the following statements BEST describes the likely outcome of the treatment?
a) Melanosomes will dissociate into chromatophores.
b) Melanosome aggregation will be inhibited.
c) Melanosome dispersal will not be affected.
d) Uniform dispersal of melanophores in the nucleus will be inhibited.
41. What is a common feature between microtubule and intermediate filaments in
fibroblast cells?
a) Polymerization is enhanced by the hydrolysis of GTP.
b) Both types of filaments undergo rapid depolymerization and repolymerization
during mitosis.
c) Both types of filaments undergo turnover during interphase.
d) Assembly of filaments is dependent on calcium ions.
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Continued…
42. A mutant p53 is likely to result in:
a) cell cycle arrest at G1.
b) a decreased response to growth factors.
c) cell cylcle arrest at G2.
d) incomplete DNA repair.
43. A key difference between mitosis and meiosis is:
a) homologous chromosomes are not paired during meiosis.
b) homologous recombination occurs during meiosis.
c) DNA synthesis occurs during interphase, only in meiosis.
d) meiosis requires a doubling of centromere.
44. In the experiment demonstrating that microtubule disassembly promotes
movement of sister chromatid towards poles, a laser light was used to:
a) bleach the kinetochore microtubules.
b) cross-link kinetochore microtububules.
c) visualize the fluorescent microtubules.
d) determine the orientation of the microtubules.
45. With respect to anaphase B, which of the following statement is FALSE?
a) Polymerization of microtubules is necessary to move the poles apart.
b) The overlap zone decreases in size with time.
c) ATP hydrolysis is required for pole separation.
d) The distance between the centrosomes increases.
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Continued…
46. Cell cycle progression in frog oocytes is promoted by progesterone:
a) after G2 arrest.
b) after M2 arrest.
c) during M1.
d) just prior to fertilization.
47. One of the functions of MPF is to:
a) target cdc2 for degradation.
b) promote nuclear membrane reassociation.
c) phosphorylate core histones.
d) phosphorylate intermediate filaments.
48. With respect to cell cycle regulation, which of the following statements is
TRUE?
a) SPF components are classified as early response genes.
b) c-fos expression activates c-jun expression.
c) Growth factors are phosphorylated by SPF.
d) Accumulation of SPF occurs after growth factor signaling.
49. Metastasis of epithelial cancer cells is often associated with:
a) decreased expression of E-cadherin by tumor cells.
b) increased expression of integrins by tumor cells.
c) the transformation of oncogenes into protooncogenes.
d) increased secretion of basal lamina components by tumor cells.
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50. How would defective cofilin affect Listeria movement inside cells?
a)
b)
c)
d)
The rat of microfilament polymerization will be enhanced.
The comet trail will remain the same size.
The comet trail should widen.
The comet trail will increase in length.
_______________________________________________________________________
The following questions 51 through 70 are based on labs 7 through 12:
51. Which of the following cellular structures is NOT detectable by a light
microscope?
a) Ribosomes.
b) Nucleolus.
c) Chloroplasts.
d) Mitochondria.
e) Vacuole.
52. Which statement is FALSE?
a) Fluorescein diacetate can cross the plant plasma membrane by passive diffusion.
b) With fluorescence microscopy, fluorescent compounds can be detected at very
low concentrations.
c) In fluorescence microscopy, the specimen absorbs light and emits it at the same
wavelength.
d) Epifluorescence microscopy is where the light passes through the objective onto
the specimen.
e) Living cells will fluoresce after treatment with fluorescein diacetate, but dead
cells will not.
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53. Which of the following statements is FALSE?
a) Köhler illumination is used to give contrast to the image of the specimen when
viewed under a light microscope.
b) The maximum resolution of a light microscope is determined by the objectives.
c) The condenser of a light microscope should have a numerical aperture equal or
higher than that of the objectives.
d) The resolution of a microscope is the minimum distance by which two objects
can be separated and still be distinguished as separate things.
e) For colour microscopy, objectives should be corrected to provide a flat field of
view and to show no chromatic or spherical aberration.
54. Which statement is CORRECT?
a) Plant cells can redistribute their organelles in response to local stimuli.
b) Plant cell walls often autofluoresce because of their carbohydrate content.
c) The largest organelle in a typical cell of a multicellular plant is the nucleus.
d) Plant cells have chloroplasts, but no mitochondria; animal cells have
mitochondria but no chloroplasts.
e) Plant cells have a cell wall instead of a plasma membrane.
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55. Your hypothesis is that fungal hyphae grow by tip growth. Which of the following
experiments would BEST show this?
a)
Determine the surface area of the fungal tip and the surface area of the vesicles
in the same region.
b)
Put the living fungus in a solution of fluorescent dye that binds to the fungal
wall. Then look for changes in fluorescence near the hyphal tip using an
electron microscope.
c)
Count the number of vesicles at the growing tip, determine their average
diameter and the rate of growth of the fungal tip membrane.
d)
Put the living fungus in a solution of fluorescent dye that binds to the fungal
wall. Then put the fungus in a solution without the dye and watch the fungus
grow using a fluorescence microscope
e)
Put the living fungus in a solution of fluorescent dye that binds to the fungal
walls. Then add fixative and look at the fungus using a fluorescence
microscope.
56. The process of cell wall modifications in French bean leaves differs from typical
secretory processes in animal cells in the following way:
a)
Glycoprotein processing in the ER is necessary for deposition of silica, callose,
and wall-bound phenolics in infected French bean leaves.
b)
Golgi apparatus is not involved in secretion of silica, callose, and wall-bound
phenolics in infected French bean leaves.
c)
Mitochondria are not essential in the secretion of silica, callose, and wall-bound
phenolics in infected French bean leaves.
d)
Vesicles are required for the secretion of silica, callose, and wall-bound
phenolics in infected French bean leaves.
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57. If the critical t-value for a two-tailed Student’s t-test is + 2.89, P= >0.05, and the
observed t-value is -5.00, what is the BEST statistically legitimate conclusion
about your data?
a)
There is a less than 5% chance that the difference between means is due to
chance alone, therefore this difference is significant.
b)
There is a greater than 5% chance that the difference between means is due to
chance alone, therefore this difference is significant.
c)
I need to re-do the experiment until I get a t-test value of 2.89.
d)
There is a greater than 5% chance that the difference between means is due to
chance alone, therefore this difference is not significant.
58. Which of the following hypotheses could BEST be investigated using
stereological analysis?
a)
Red blood cells hemolyse in a 0.1 M solution of NaCl.
b)
Mitochondria and chloroplasts have a different shape.
c)
Mitochondria move faster than chloroplasts in tomato hair cells.
d)
Vesicles are more frequent at the apical end of an intestinal epithelial cell.
e)
Glutaraldehyde is a better fixative of sea urchin eggs than is potassium
permanganate.
59. One reason for the difference in the composition of the test solution used for the
actomyosin gel preparation and the glycerinated muscle preparation is:
a)
EDTA is required to remove endogenous Ca2+ and Mg2+ from the glycerinated
muscle preparation.
b)
Ca2+ is included in the glycerinated muscle preparation because the
tropomyosin/troponin complex is intact.
c)
the glycinerated muscle preparation needs to be more strongly buffered.
d)
a lower concentration of salts is required in the glycerinated muscle preparation
to give optimal contraction.
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60. Ca2+ is necessary for muscle contraction because it
a)
acts as a co-factor for ATP.
b)
enhances the activity of myosin ATPase.
c)
removes the troponin complex from F-actin.
d)
stimulates the release of ADP from myosin.
e)
allows the binding of the myosin heads to F-actin.
61. In electron micrographs of fungal hyphal tips, indentations in the plasma membrane
contain dark particles that look similar to particles visible inside small vesicles within
the fungal hyphae. Which statement is scientifically CORRECT, based on these
observations?
a)
These observations prove that fungi secrete cell wall material through
exocytosis.
b)
These observations suggest that fungi can take up food by endocytosis.
c)
These observations prove that the vesicles come from the trans-Golgi reticulum.
d)
These observations could be the result of either endocytosis or exocytosis at the
hyphal tip.
e)
These observations prove that the small vesicles fuse with, and increase the
surface area of, the fungal plasma membrane.
62. One way to identify female fruit flies is to
a)
select flies with non-protruding genetalia.
b)
select flies with light brown wings.
c)
select flies with black abdomens.
d)
select flies without black abdomens.
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63. The two types of germline cells within the Drosophila follicle are?
a)
Oocyte and stem cells.
b)
Nurse cells and epithelial cells.
c)
Oocyte and nurse cells.
d)
Nurse cells and sperm cells.
64. This question was ambiguous and not counted; intended answer was “a”.
With respect to the formation of germ cells in a developing Drosophila embryo:
a)
germ cells form after the formation of a single layer of nuclei in the periphery of
the egg.
b)
germ cells form prior to fertilization.
c)
germ cells form immediately following the formation of the blastoderm.
d)
germ cells form synchronously with the formation of the single layer of nuclei
in the periphery of the egg.
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Continued…
65. You have just discovered a new protein that you hypothesize may be a motor protein
that binds to and distributes RNA to the anterior end of the developing Drosophila
embryo. Which of the following describe possible experiments that you could
perform to test this hypothesis? Give a complete list.
1. Make a transgenic Drosophila line that has a transgene consisting of the DNA for
the proposed motor protein and DNA for -galactosidase and look to see whether
blue is found at the anterior end of the transgenic embryos.
2. Purify the motor protein and determine whether it binds to RNA.
3. Perform immunohistochemistry on fixed Drosophila embryos using an antibody
that is specific for the motor protein to see whether the protein localizes to the
anterior end of the embryo.
4. Fluorescently label the motor protein and incubate it along with live Drosophilia
embryos. Observe whether the fluorescence moves to the anterior end of the
embryo.
5. Make a mutant Drosophila line that lacks the motor protein and look to see
whether RNA moves to the anterior end of the embryo.
a)
1, 2, 3, 4, 5.
b)
2, 4, 5.
c)
2, 3.
d)
1, 3, 4.
e)
1, 2, 3, 5.
66. Movement of Listeria in the cytoplasm of cells requires many cellular proteins. One
of the proteins involved is cofilin, also known as ADF. The function of cofilin is to:
a)
promote actin assembly at the barbed end of the microfilament.
b)
cap the pointed end of the microfilament.
c)
enhance disassembly of the microfilament at the pointed end of the
microfilament.
d)
promote exchange of ADP for ATP to re-charge the actin monomers.
e)
bind to ActA to promote actin assembly at the pointed end of the microfilament.
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Continued…
67. What is a cell cycle checkpoint?
a) The stage in the cell cycle where the cell divides.
b) The stage in the cell cycle where specific tasks must be completed before the next
stage can begin.
c) The stage in the cell cycle where the nucleus confirms that the DNA sequence is
correct.
d) A DNA sequence that signals the cell to begin synthesis.
68. What is the proposed damage-control system that blocks chromosome
segregation when the checkpoint control fails?
a) Centrosome inactivation.
b) Microtubule paralysis.
c) Retardation of movement of γ-tubulin ring complex.
d) Degradation of intermediate filament (IF) structure in cytoplasm.
69. Cell-cell adhesion is achieved by cadherin through:
a) interaction of C-terminal extracellular regions of two adjacent cadherin
molecules.
b) interaction of C-terminal cytosolic regions of two adjacent cadherin molecules.
c) interaction of N-terminal extracellular regions of two adjacent cadherin
molecules.
d) interaction of N-terminal cytosolic regions of two adjacent cadherin molecules.
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Continued…
70. Which of the following statements is FALSE with respect to the scientific
approaches and conclusions described in the article (#3) Drosphila Oocyte
Localization is mediated by Differential Cadherin-based Adhesion:
a) these experiments (by Godt and Tepass) were carried out in vivo in Drosophila.
b) Shg mutants had a defect in the shotgun gene and therefore could not express DECadherin.
c) mosaic models of the epithelial follicle layer were used to demonstrate the
oocyte’s affinity for the highest levels of cadherin.
d) different regions of follicle cells expressed the same amount of cadherin.
THE END
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