Download Multiple Choice - 32 points total In each of the questions, select the

Multiple Choice -
32 points total
In each of the questions, select the answer which you believe is most nearly correct and write it in the
blank. If more than one answer seems to be correct, pick the single answer you believe to be the best.
1)
E
Adult human stem cells
A) are derived from the inner cell mass of the blastocyst.
B) are found in the bone marrow.
C) are generally not pluripotent.
D) are associated with self-renewing tissues.
E) All of the above.
2)
E
John Gurdon shared the Nobel Prize in 2012 for experiments in which he used nuclear
transplantation to
A) Determine the role of mRNA in cell differentiation.
B) Develop the technique of shotgun DNA sequencing.
C) Repair damaged heart muscle tissue in mice.
D) Discover the process of apoptosis.
E) None of the above
3)
D
A typical plasmid, used as a vector to transform bacteria
using recombinant DNA techniques, generally includes all of the
following except
A) Restriction enzyme cutting sites
B) Antibiotic resistance genes
C) An origin of replication
D) PCR primer sequences
E) None of the above (Because a typical plasmid actually contains
all of these)
4)
D
Which of the following questions would be best addressed using microarray analysis?
A) How many genes are present in the human genome?
B) What is the approximate mutation rate of the human Β-actin gene?
C) How similar is the human genome to the mouse genome?
D) What subset of human genes is uniquely expressed in the liver?
E) What is the primary function of the human Β-actin gene?
Bio 0200 - 2013 – 3rd Exam Answer Key
5)
A
Which of the following locations in a giraffe would register
the highest blood pressure?
A) An artery in the head of a giraffe as it bends over to take a drink of
water (head at level of feet)
B) A vein in the leg of the giraffe.
C) An artery in the lungs of the giraffe
D) A vein in the lungs of the giraffe
E) The aorta of the giraffe
6) _____ E_____Increasing activity in the sympathetic nervous system
would cause
A) increased total peripheral resistance
B) decreased blood pressure
C) increased heart rate
D) decreased cardiac output
E) More than one of the above
7) _____ E_____Which of the following statements about the left ventricle is/are true?
A) The left ventricle is more muscular than the right ventricle.
B) The blood in the left ventricle has more oxygen than the blood in the right ventricle.
C) The valves regulating the filling and emptying of the left ventricle are the atrioventricular
valve and the aortic valve.
D) More than one of the above
E) All of the above are true.
8)_____ C_____A synapse that uses the amino acid glutamate as a neurotransmitter
A) contains glutamate receptors in the presynaptic membrane.
B) responds directly to increases in glutamate in the blood caused by eating a meal high in
protein.
C) requires calcium entry into the presynaptic terminal in order for synaptic vesicle release to
occur.
D) will take more time to elicit a response than signals sent through the endocrine system.
E) can cause responses throughout the body as glutamate is picked up by the circulatory system.
Formulas you may find useful for these and other questions:
Page 2
Bio 0200 - 2013 – 3rd Exam Answer Key
9) Control of Gene Expression (16 points)
As you know, in class, we have discussed two different operons, lac and tryp. the lac operon is a group
of three genes in E. coli that code for proteins in the pathways that metabolize lactose. The tryp operin
is a group of 5 genes that code for protein enzymes in the pathway that synthesizes the amino acid
tryptophan. The structure of the lac operon is shown below:
Transcription of the lac operon, as you know, is dependent on the presence or absence of food
molecules such as glucose and lactose. Normally, transcription of the operon in the presence or absence
of these two molecules produces this pattern of transcription:
Lactose
+
+
—
—
Glucose
+
—
+
—
Transcription
Low
High
Low
Low
You are studying three different mutations in the three different DNA-binding proteins associated with
these two operons. Predict the effects of each of these mutations on the level of transcription of these
operons under the conditions shown below.
A) Mutation Lac-2 deletes the DNA binding site from the lac repressor protein, but leaves the rest of
the protein otherwise unaffected. Predict the effect of this mutation on transcription in the lac operon.
You need only write “High” or “Low” in the table — no explanation needed.
Lactose
+
+
—
—
Glucose
+
—
+
—
Transcription
Low
High
Low
High
B) Mutation Lac-6 deletes the DNA binding site of the CAP protein, but leaves the rest of the protein
otherwise unaffected. Predict the effect of this mutation on transcription in the lac operon.
Lactose
+
+
—
—
Glucose
+
—
+
—
Page 3
Transcription
Low
Low
Low
Low
Bio 0200 - 2013 – 3rd Exam Answer Key
C) Predict the level of transcription that would occur if both mutations (Lac-2 and Lac-6) were found
in the same cell.
Lactose
+
+
—
—
Glucose
+
—
+
—
Transcription
Low
Low
Low
Low
Parts D and E concern the tryp operon.
• The structure of the tryp operon is shown below:
D) Predict the level of transcription that would be observed for the tryp operon under the conditions
shown below. You need only write “High” or “Low” in the table — no explanation needed.
Tryptophan
+
—
Glucose
+
+
Transcription
Low
High
E) Mutation Tryp-3 deletes the DNA binding site from the tryp repressor protein, but leaves the rest of
the protein otherwise unaffected. Predict the level of transcription that would be observed for the tryp
operon under the conditions shown below.
Tryptophan
+
—
Glucose
+
+
Page 4
Transcription
High
High
Bio 0200 - 2013 – 3rd Exam Answer Key
10) Human Genomics (16 points)
The human androgen receptor (AR) gene has 8 exons. A group studying the expression of this gene
isolated total mRNA from a variety of tissues. The mRNA was then run on a gel to separate the
transcripts based on their lengths. Finally, the researchers applied an AR specific probe to the separated
transcripts. This was done to make AR-specific
transcript visible. As a control, the group also
used a probe specific for a second gene called
GAPDH, making its transcript visible as well.
This gel shows their results:
As you can see, AR expression is the same in
heart muscle as it is in 11-day old embryo. For
each of the remaining samples, explain the
difference between AR expression in
heart/embryo and the tissue in question as
indicated by the results. Include an explanation of
a potential cause of the difference.
A) What is the difference between AR expression in the heart / 11-day embryo and AR expression in
the brain? (3 points)
AR is expressed in both heart and 11 day-old embryo, but it is not expressed in the brain.
Grading note: -1 for referring to expression levels (since the positions of bands indicate the
lengths of mRNA molecules, not the level of expression!)
B) What is the difference between AR expression in the heart/ 11-day embryo and AR expression in the
liver? (3 points)
AR is expressed in both heart and 11 day-old embryo (+1 pt.). It is also expressed in the
liver (+1 pt.), but the resulting mRNA is a different length (+1 pt.).
Grading note: -1 for referring to expression levels.
C) Propose a possible reason for this difference in part B (above). (2 points)
This could be the result of alternative splicing or use of an alternative promotor.
(2 points for either answer)
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Bio 0200 - 2013 – 3rd Exam Answer Key
D) Very briefly explain why the investigators would have
found it necessary to include a probe for mRNA from the
GAPDH gene as a control. (4 points)
GAPDH is expressed in all of the tissues tested
and is therefore useful as a positive control.
Grading note: The answer need not specifically say
“positive control,” but it should make it clear that
the GAPDH probe is included to ensure that overall mRNA expression levels are the same in
all samples (or something similar)
E) Preliminary results indicate that in some tissues, DNA in the promoter sequence for the AR gene is
heavily methylated. In which of the four tissues studied in the experiment is the most extensive DNA
methylation of the promoter sequence likely to be found? Name the tissue, and then explain your
choice. (4 points)
Name the tissue: Brain tissue. (2 points)
Explanation: Heavily methylated promotor sequences are associated with reduced
expression of adjacent genes. (2 points)
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Bio 0200 - 2013 – 3rd Exam Answer Key
11) Homeostasis (18 points)
A) A small heating device is attached to your hypothalamus which allows for the isolated heating of
this one, small part of the body. It will only heat up the hypothalamus, not your whole body. The
temperature of your hypothalamus is increased by 2 degrees Celsius (4 degrees Fahrenheit).
a) Which of the following statements are you most likely to say? (circle one) (3pts)
“I feel cold!”
“I feel warm!”
b) Your core body temperature, measured the most accurate way (with a rectal probe), registers 37
degrees Celsius (98.7 degrees Fahrenheit). What is going to happen to your body temperature when
this heating device is turned on? (circle one) (3pts)
It will go up.
It will go down.
c) Give two examples of effector systems that would accomplish this change in body temperature.
(4pts)
-Sweating;
If Heating is chosen give points for
-Shunting blood to surface of body (skin)
-Shivering
-Moving to a cool environment
-Shunting blood away from skin
-Seeking warm environment/put on clothing
d) Why will these effector systems never turn off under these experimental conditions? (1pt)
The response system will cool the body but the hypothalamus will continually be heated by the
experimental device.
e) In one sentence, explain the mechanism by which a bat’s body temperature drops below 35 deg C
when it is in torpor in a cold environment. (3pts)
When a bat is in torpor its setpoint for temperature is lowered.
B) Another device stimulates all of the axons of parasympathetic neurons in your peripheral nervous
system. What would be the effect(s) of increasing parasympathetic activity on these organs? (4pts)
a) Heart
Slower heart rate and weaker contraction (less forceful contraction)
b) Blood vessels
No change
(There is no direct effect of increasing parasympathetic activity on blood vessels because they are not innervated by
parasympathetic axons.)
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Bio 0200 - 2013 – 3rd Exam Answer Key
12) Messing with Neurons (18 points)
Ion X+ is positively charged and in equal concentrations on the inside and outside of a typical neuron
membrane. The concentration inside is 100 mM/L and outside is 100 mM/L. (see Formulas on page 3).
A) What is the equilibrium potential of X+? (3pts)
0 mV
B) With all X+ channels in the membrane closed the membrane potential rests at -65 mV. Given the
concentrations listed above, what would happen to the membrane potential if a large number of X+
channels opened? (3pts)
The membrane potential would move toward 0 mV from -65 mV (i.e. depolarize).
C) You are recording the membrane potential of a neuron that is stimulated at time zero with a stimulus
that is strong enough to bring the neuron to fire an action potential. You are now going to perform 2
different experiments where you stimulate under normal conditions first and then stimulate under
experimental conditions second. Below are the control responses for each of the 2 experiments. Draw
on each plot the response that would be expected under the experimental conditions listed.
Expt. 1 Voltage-gated K+ channels (delayedrectifier K+ channels) are blocked (3pts)
Expt. 2 The number of voltage-gated Na
channels is increased by 50% (3pts)
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Bio 0200 - 2013 – 3rd Exam Answer Key
D) One of the side effects of excessive diarrhea is loss of potassium from the body. A decrease in
extracellular potassium (K+), or hypokalemia, will have a dramatic effect on the membrane potentials
of all cells.
• Explain how a decrease in the concentration of extracellular potassium would affect the membrane
potential of neurons. (4pts)
A decrease in the concentration of extracellular potassium ([K+]out) would result in a more negative
equilibrium potential for potassium across the cell membrane.
EK+ =
61mV
1
log [K+]out
[K+]in
As numerator gets smaller the magnitude of the negative equilibrium potential would become greater.
• Would neurons be more or less likely to fire action potentials under these circumstances? (2pts)
Neurons would be less likely to fire action potentials.
(A more negative equilibrium potential for potassium would result in a more negative resting
membrane potential.)
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