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Transcript
Please read Science 1
Which of the following statements best
describes why Experiment 1 is
important?
1. Experiment 1 demonstrates that insects
can thrive under the given conditions.
2. Experiment 1 establishes that both
Beetle A and Beetle B eat whole-wheat
flour.
3. Experiment 1 establishes the noncompetitive total population of each
insect.
4. Experiment 1 demonstrates that the
caterpillar has a much slower growth
rate than the beetles.
1
2
3
Explanation
Experiment 1 is a control experiment that
establishes the population size of each insect
when provided with an adequate food supply
for any size population. This population size is
used to compare what happens when there is
less food and/or more species eating the
same finite supply of food.
If Beetle A in Experiment 1 was left to
grow indefinitely, one would initially
observe an increase, followed by a brief
plateau, and then a rapid decline in the
population size. What would be the most
likely cause of the final decline?
1.
2.
3.
4.
1
Other species of insects
Limited supply of food
Limited supply of minerals
Long-term effects of confinement
2
3
Explanation
 The most likely limiting resource that is
discussed and applicable to the
paragraph is food supply. Over an
indefinitely long period of time, the food
supply would run out and population size
would cease to increase. The population
size would eventually start declining due
to starvation.
What would happen if, in Experiment 2,
Beetle B and caterpillars were put in the
same vial?
1. The caterpillars would die by Week 10 because of
overpopulation by Beetle B.
2. The average population of Beetle B would reach
100 and the average population for caterpillars
would reach 5 because of competition for food.
3. The average population of caterpillars would
reach 50 while Beetle B would die because
caterpillars are stronger competitors for food.
4. The average population of Beetle B would reach
500 while the average population of caterpillars
would reach 20, as in Experiment 2.
1
2
3
Explanation
 While Experiment 3 suggests that both
species of beetles compete for food,
Experiment 2 suggests that Beetle A
does not compete with caterpillars for
food. Therefore, Beetle B should not be
expected to compete with the caterpillars
for food either.
Which of the following statements is
true of Experiment 3?
1. Beetle B is the more dominant of the
two beetle species.
2. Beetle A and Beetle B compete for
space, food, or both.
3. The population size of beetle B is
smaller than Beetle A due to migration.
4. The population size of Beetle B is
smaller than Beetle A due to the
absence of the caterpillars.
1
2
3
Explanation
 The decrease in both Beetle A and Beetle
B population sizes indicate that there is
interspecies competition for
resources. All the other statements are
not true.
Suppose that, instead of starting with six
of each species in Experiment 3, only
three of each species were placed in the
vial. After ten weeks, what percentage
of the total population would the Beetle
B species constitute?
1.
2.
3.
4.
1
15%
25%
75%
85%
2
3
Explanation
 The ratio of Beetle A to Beetle B should
remain the same regardless of the initial
number of beetles. Hence, Beetle A
constitutes 75% while Beetle B
constitutes 25%.
Suppose another species of beetle, Beetle C,
replaces Beetle A in Experiment 3. After ten
weeks, only the Beetle C species can be
found in the vial. Which of the following
hypotheses does NOT explain the result in
terms of competition?
1.
2.
3.
4.
1
The adult and larval Beetle C species ate the eggs
and pupae of the Beetle B species.
The Beetle C species hoarded the food supply and
defended it from the Beetle B species.
The Beetle B species was unable to reproduce due
to a genetic mutation.
The Beetle C species secretes an enzyme on the
food supply that can only be broken down by its own
digestion system
2
3
Explanation
 The dearth of the Beetle B species in all
the other choices is due to a result of
direct influence of the Beetle C
species. The failure to reproduce due to
a genetic mutation is not a result of
competition.
Please read Science 2
Which of the following scenarios
definitively exemplifies drug resistance?
1. A specific antibiotic treats a broad spectrum of
bacterial infections.
2. A specific antibiotic does not treat bacterial
infections caused by Staphylococcus.
3. A specific antibiotic has become ineffective in
treating bacterial infections from some strains of
Staphylococcus.
4. A specific antibiotic treats bacterial infections
from Staphylococcus but does not treat
bacterial infections from the bacterium
Pseudomonas.
1
2
3
Explanation
 Drug resistance, defined in paragraph 1,
is the ability to resist the effects of a
once-potent antibiotic. #3 satisfies this
definition.
Which statement is true of the given
distribution curves?
1. The unshaded region in Curve 1
represents 5% drug non-resistance.
2. Curve 2 represents 100% drug
resistance.
3. Curve 1 represents 95% drug
resistance.
4. Curve 2 is not related to drug
resistance.
1
2
3
Explanation
 The unshaded region in curve 1
corresponds to strains of bacteria that
are resistant to antibiotics. Thus, curve 2
arises from the survival of these strains.
Which of the following conclusions is NOT
consistent with the results of the
experiment?
1. Doxycycline had no effect on
Staphylococcus.
2. Kanamycin and ethambutol were about
equally effective on Staphylococcus.
3. Streptomycin was effective at all
concentrations on Staphylococcus.
4. Sulfamethoxazole was effective only at low
concentrations on Staphylococcus.
1
2
3
Explanation
 From the table, sulfamethoxazole
prevents growth at high concentrations.
Its effectiveness diminishes as its
concentration decreases, as seen by
strong growth. Thus, sulfamethoxazole
was most effective at high
concentrations.
If the concentration of antibiotics used is
to be kept at a minimum to prevent drug
resistance, which of the antibiotics listed
in the table would be the best choice for
treatment of Staphylococcus?
1.
2.
3.
4.
1
Kanamycin
Ethambutol
Streptomycin
Sulfamethoxazole
2
3
Explanation
 From the table, streptomycin still
prevented bacterial growth at the lowest
concentration whereas all the other
antibiotics were ineffective.
Suppose that a strain of bacteria arose
which was resistant to
streptomycin. Which of the following
scenarios would you expect to occur in
the course of time?
1.
The streptomycin-resistant strain would come to dominate
the population of bacteria as the other strains died off after
being exposed to antibiotics.
At least one of the other antibiotics would prove effective in
treating the streptomycin-resistant bacteria.
The new strain of bacteria would become the source of a
new family of antibiotics useful in treating previously
intractable infections.
The distribution curves for bacteria treated with
streptomycin would now include a substantial shaded
region on the right-hand side.
2.
3.
4.
1
2
3
Explanation
 The distribution curves show that, over the
course of time, the strains of bacteria which
can be treated using any specific antibiotic die
off, leaving a population of bacteria consisting
solely of drug-resistant strains. If we start with
a strain of bacteria which we know to be
resistant to the most effective antibiotics, we
can confidently expect that this strain will come
to dominate the population of bacteria.
Please read Science 3
The characteristics common
to the studies is that both:
1. measured periods of maximum
glaciations
2. utilized ancient and modern
sedimentary rocks
3. analyzed data from marine sediments
4. measured the depth of the cycles
1
2
3
Explanation
 Both studies state that they are analyzing
marine sediment. Study 2 makes no
mention of sedimentary rocks (ruling out
#2). Depth of the cores is irrelevant
(ruling out #4) and only study 2 states
that it measured peak glaciation (ruling
out #1).
Which of the following characteristics of
a sequence of marine sediments or
sedimentary rocks would make it
unsuitable for a study such as this?
I. an age of only 30,000 to 40,000 years
II. depth of ocean water
III. location away from the polar ice caps
1.
2.
3.
4.
1
I only
II and III only
I, II, and III
I and III only
2
3
Explanation
 The passage makes no mention of the
relevance of ocean depth or proximity to
polar ice caps, but it does mention that
these sequences have a minimum age of
50,000 years.
Each of the following is true
EXCEPT:
1. Both studies are compatible with the claim that
major climate changes occur at intervals of
50,000 years or more.
2. Both studies provide support for the claim that
cyclic climate changes caused changes in
sediment patterns.
3. Sediment size was a central factor in the
results of both studies.
4. Both studies concerned ancient marine
sedimentary rocks.
1
2
3
Explanation
 Sediment size was the crucial factor in
Study 1 but not Study 2 (where the
central factors were the abundance and
shape of microfossils).
According to the theory discussed in the
passage, as glacial melting increases,
the sediments along coastlines and
microfossils within oceans should
respectively show:
1. more deposition and cooler global
temperatures
2. more erosion and cooler global
temperatures
3. more deposition and warmer global
temperatures
4. more erosion and warmer global
temperatures
1
2
3
Explanation
 As stated in the second paragraph,
glacial melting results in deposition and
warmer global temperatures.
Which of the following
hypotheses was investigated
in Study 1?
1. Changes in sea level cause sequences
of sediments.
2. Cycles occur every 50,000, 100,000, 5
million and 12 million years.
3. The sea level is currently rising.
4. Cyclicity in sediment deposition is the
result of changes in global ice volume.
1
2
3
Explanation
 Study 1's hypothesis was that marine
sediments record sequences of sediment
that occur in cycles. #2 is the conclusion
of study 1, not a hypothesis. #1 and #3
are not discussed in Study 1.
Please read Science 4
Which one of the following
statements best describes why
Experiment 1 is important?
1.
Experiment 1 shows that the hamsters need an
average of 10 hours of sleep.
Experiment 1 is used as a basis of comparison by the
other experiments.
Experiment 1 shows that hamsters exercise
regularly.
Experiment 1 has no relation with the other
experiments.
2.
3.
4.
1
2
3
Explanation
 Experiment 1 is a control experiment that
establishes the behavior of hamsters
under normal conditions. Conclusions
drawn from all the other experiments are
based on comparisons to Experiment 1.
Which of following
statements is NOT
consistent with hamster
sleep patterns?
1.
The greater the dark exposure in a 24-hour
period, the less a hamster sleeps.
The length of light exposure affects a hamster’s
sleep pattern.
Under normal conditions, a hamster will sleep
an average of 10 hours.
The greater the light exposure in a 24-hour
period, the less a hamster sleeps.
2.
3.
4.
1
2
3
Explanation
 From the “Hamster sleep pattern” graph,
the greater the dark exposure
(Experiment 3), the more a hamster
sleeps.
What would one expect to
observe at Day 3 if the
hamsters were exposed to
15 hours of light?
1. The hamsters would sleep and exercise less.
2. The hamsters would sleep and exercise
more.
3. The hamsters would sleep less and exercise
more.
4. No change from the normal would be
observed.
1
2
3
Explanation
 From the graphs, it is clear that the
hamsters need at least 5 days to respond
to a 20-hour light exposure. Hence, no
observable change would occur at Day 3
even at a 15-hour light exposure.
Which of the following
statements is true regarding
hamster exercise patterns?
1. Normal hamster sleep patterns lead to a
steady decrease in the number of hours
hamsters exercise a day.
2. Hamsters exercise more when more food is
provided.
3. Hamsters deprived of light will eventually
exercise very little or not at all.
4. Sleep deprivation and exercise are not
related.
1
2
3
Explanation
 According to the “Hamster exercise
pattern” graph, the odometer for
hamsters in Experiment 3 plateaus after
the eighth day, indicating that all exercise
has ceased or decreased to negligible
levels.
In view of the experimental results on
hamsters, which of the following
statements is a sound hypothesis
regarding the behavior of mice exposed
to light for abnormally long periods
during 24-hour days?
1.
The mice will not react, either in sleep patterns or in
exercise patterns, protracted exposure to light.
The mice will sleep more and exercise less than the
hamsters when exposed to light for protracted
periods.
The mice will exhibit a rapid increase in the number of
exercise hours, reaching a cumulative distance of
about 200 kilometers in 10 days.
The mice will react the same way as the hamsters to
prolonged light exposure, but this reaction will not
necessarily take place at the same rate.
2.
3.
4.
1
2
3
Explanation
 Given the gross similarities between mice and
hamsters, it is reasonable to expect them to
respond similarly to prolonged light exposure
(and there is no evidence suggesting
otherwise, ruling out 1 and 2). The two are
different species, however, and the hypothesis
that predicts identical behavior (3) is too strong
for that reason. Another set of similar
experiments will have to be performed to
definitively determine the time frames for mice.
If the hamsters in Experiment 3 were
put under normal conditions again after
Day 20, what would most likely be
observed?
1. No observable changes will occur as the
hamsters have grown accustomed to sleeping
in and not exercising.
2. No observable changes will occur as the
hamsters’ circadian rhythms were destroyed.
3. The hamsters will increasingly sleep less and
exercise more to a point that matches
Experiment 2.
4. The hamsters will increasingly sleep less and
exercise more to a point that matches
Experiment 1.
1
2
3
Explanation
 Since the effects on the disruption of
circadian rhythm is reversible, as
mentioned in the passage, the hamsters’
sleep and exercise patterns will
eventually reflect those of hamsters that
experience normal light and darkness
exposure.
Please read Science 5
Which statement
characterizes the migration
of SDS-associated proteins?
1. Diffusion moves the proteins from a region of
higher concentration to one of lower
concentration.
2. An electric field causes negatively charged
objects to migrate toward the anode (positive
end).
3. The electrical resistance of negatively charged
objects determines the speed of migration.
4. Osmosis of water indirectly causes the
migration of the proteins.
1
2
3
Explanation
 SDS-associated proteins, which are
negatively charged, will travel toward the
positive end of an electric field. All the
other options are true statements, but do
not describe the SDS-PAGE context.
A protein of weight 45 000 Da
would be expected to migrate
to the region on the graph
marked
1.
2.
3.
4.
1
W.
X.
Y.
Z.
2
3
Explanation
 From the table, the weight 45 000 falls
between the first 2 data points. This
would correspond to region W on the
graph.
A protein essential for metabolism
has just been discovered. SDSPAGE reveals that this protein
migrates a distance of 1.7
cm. Which statement best
characterizes the new protein?
1.
The weight of the protein is somewhere between 6
000 Da and 11 000 Da.
The weight of the protein is somewhere between 11
000 Da and 17 000 Da.
The weight of the protein is somewhere between
14 000 Da and 17 000 Da.
The weight of the protein is somewhere between
17 000 Da and 35 000 Da.
2.
3.
4.
1
2
3
Explanation
 Since a protein weighing 17 000 Da
travels 1.8 cm, and since the new protein
traveled only 1.7 cm, we can confidently
conclude that the new protein is heavier
and thus rule out answers #1, #2, and
#3. #4 is the only answer allowing for
heavier weights.
Another essential protein in metabolism
is made up of 2 units, each unit
traveling a different distance from the
other. The combined weight of the 2
units is approximately 50 000
Da. Referring to the regions W, X, Y
and Z on the graph, which combination
will NOT give the possible weight of
each unit?
1.
2.
3.
4.
1
X+Z
Y+Z
X+Y
W+Y
2
3
Explanation
 All the other combinations can be
manipulated to give a combined weight of
approximately 50 000 Da. The highest
weight that Y + Z can attain under 25 000
Da.
What would happen if an
electric field were to be
applied to SDS-PAGE for an
indefinite length of time?
1.
Larger proteins will reach the anode before the
smaller proteins.
All proteins will eventually reach a limiting
resistance in the matrix, at which point they cease
to migrate further.
Proteins associated with more SDS will reach the
anode while proteins associated with less SDS will
stop migrating due to resistance.
All proteins will eventually reach the anode.
2.
3.
4.
1
2
3
Explanation
 It is consistent with the information
provided that, given an indefinitely long
period of time, all negatively charged
proteins will reach the anode at the rates
determined by their sizes. Smaller
proteins will arrive at the anode before
the larger proteins, ruling out #1.
Please read Science 6
The final three-dimensional
structure of a protein, regardless of
the folding pathway models,
ultimately depends on:
1.
2.
3.
4.
1
2
how it is manufactured by the cell.
the flexibility of the peptide bonds.
the number of amino acids.
the sequence of the amino acids.
3
Explanation
 The passage states (in the first sentence)
that each protein is characterized by the
sequence of amino acids and that this
sequence is what makes the protein
unique.
A mutation of an important amino
acid affects the proper conformation
of the protein. Which of the
proposed models cannot account for
this observation?
1.
2.
3.
4.
1
Diffusion-collision model.
Nucleation model.
Hydrophobic-collapse model.
None of the above.
2
3
Explanation
 All the models are based on the fact that
the amino acid sequence specifies the
proper conformation. A loss of a vital
amino acid in any of the models would
lead to the wrong conformation.
A certain mutation of an amino
acid, which is thought to play a
major role in initiating protein
folding, does not affect the general
structure of the protein. Which of
the proposed models cannot
account for this observation?
1.
2.
3.
4.
1
Diffusion-collision model
Nucleation model
Hydrophobic-collapse model
None of the above
2
3
Explanation
 According to the nucleation model, the
mutated amino acid will fail to produce a
properly folded protein. However, the
protein still acquires the proper fold,
suggesting the shortfall of this model.
The nucleation model suggests that some
amino acids are more important than
others whereas the diffusion-collision
model supposes that all amino acids are
equally important. Which of the following
statements is NOT true?
1.
2.
3.
4.
1
2
A mutation in an important amino acid in the
nucleation model will have no effect according to the
diffusion-collision model.
A mutation in an amino acid, which is important in the
nucleation model, will result in a wrong
conformation.
A mutation in an amino acid might affect proper
protein conformation according to the diffusioncollision model.
A mutation in a certain amino acid might have an
effect according to both the nucleation model and the
3
diffusion-collision
model.
Explanation
 Even though the diffusion-collision model
does not posit that there are any
especially important amino acids, it is still
the case, according to that model, that a
mutation of any amino acid might affect
the folding pathway
Implicit in the nucleation
model is the assumption
that:
1. temperature is an important factor for a protein
to attain the proper conformation
2. the presence of salt promotes a protein in
attaining the proper conformation
3. the addition of a strong base will destroy the
peptide bonds and thus the protein
4. the time required to attain the proper
conformation is dependent on the length of the
protein
1
2
3
Explanation
 Since the nucleation method is akin to a
domino effect, it follows that the longer a
protein, the longer it will take to attain the
proper conformation.
A molecular chaperonin is a protein that aids
small proteins in establishing their
structures. The chaperonin has a barrel-like
cavity that provides an unfolded protein an
opportunity to fold. If the hydrophobic-collapse
model can be used to explain this particular
folding process, what can be said about the
amino acids of the molecular chaperonin that
come in contact with the unfolded protein?
1.
The amino acids in the molecular chaperonins are
hydrophobic.
The amino acids in the molecular chaperonins are
hydrophilic.
The amino acids in the molecular chaperonins are
both hydrophobic and hydrophilic.
The amino acids in the molecular chaperonins are not
involved in the folding process.
2.
3.
4.
1
2
3
Explanation
 According to the hydrophobic-collapse
model, hydrophobic amino acids prefer to
interact with themselves. Thus, the
interacting molecular chaperonin amino
acids must be hydrophilic to promote
protein folding.
A fourth, all-inclusive view of protein
folding is that similar proteins can
fold via any of the three
models. What cannot be said of
proteins that conform to this allinclusive model?
1. The structure of a protein can be attained by
any model.
2. The length of the protein does not influence
the choice of a model.
3. The sequence of the protein determines the
folding pathway.
4. A folding pathway that is hindered by a
mutation can be compensated by another.
1
2
3
Explanation
 Statements #1 and #4 demonstrate that a
protein fold can be achieved by any of the
three suggested pathways. While sequence is
the only element important in the folding
process, hence negating Statement #2, the fact
that similar proteins can attain proper
conformations via any of the proposed
pathways, in this particular case, suggests that
sequence does not determine the folding
pathway.
Please read Science 7
Which of the following statements is
supported by the data presented in
the graph?
1. Amount of clay depends on time only
2. Amount of clay depends on time and
climate
3. Climate depends upon amount of clay only
4. The graph does not support a relationship
between climate, amount of clay, or time
1
2
3
Explanation
 The three variables described in the
passage and shown on the graph
indicate a relationship that can only be
explained by climate, time, and amount
of clay.
The graph indicates that after
100,000 years the greatest change
in amount of clay (g/cm3) has
occurred in which climate?
1.
2.
3.
4.
1
Climate XX
Climate ZZ
Climate TT
Climate WW
2
3
Explanation
 Climate XX, because the graph is
logarithmic, climate XX has experienced
a change from 0 g/cm3 to 30 g/cm3.
Climate ZZ only changes from 0 to 15
g/cm3.
For any given climate, which of the
following generalizations is
supported by the graph?
1. As time increases, the amount of clay present
increases.
2. As time increases, the change in amount of
clay decreases.
3. As the amount of clay increases, the change in
the amount of clay decreases.
4. As time increases, the amount of clay present
changes.
1
2
3
Explanation
 The other answers are not true. D is true
because, whether the change is an
increase or a decrease, there always is a
change between two points in time for
any given climate.
Based on the information in this
graph, an extended graph including
data up to 10,000,000 years would
show the least change in amount of
clay present in which climate?
1. Climate ZZ
2. Climate WW
3. Climate TT
4. Climate QQ
1
2
3
Explanation
 Climate QQ has a relatively stable slope,
indicating small changes in amount of
clay present. Slopes for all other graphs
are steeper.
A ranking of these soils from most
developed to least developed changes
significantly between 1,000-10,000
years and 10,000-100,000 years. If we
extended this graph back to include
data to 0 years, which of the following
could be predicted to occur?
1. Climate TT and YY would have equal
ranking.
2. Climate YY would have the highest ranking.
3. All soils would have equal ranking.
4. Climate TT would have the highest ranking.
1
2
3
Explanation
 As stated in the passage, all soils began
with no clay present, and the graph also
supports this assertion where soils in
climates XX, ZZ, WW, and QQ develop
clay much later than time 0 years.
Please read Science 8
Which statement explains
some of the strategy
employed in experiment 1?
1.
Adding a radioactive label to the LDL particle ensured
that the particle would be soluble in the blood.
Adding a radioactive label to the LDL particle allowed
the rate of transport to be measured.
Adding a radioactive label to the LDL particle allowed
the test animal to metabolize the LDL.
Adding a radioactive label to the LDL particle altered
the protein component of the particle.
2.
3.
4.
1
2
3
4
5
Explantion
 The correct answer is 2. The addition of the radioactive
label on the LDL particle allowed the researcher to
measure radioactive levels in the blood against other
tissues. This, in turn, allowed the researcher to follow the
rate of transport of the LDL. As the hypothesis stated that
the transport of the LDL is dependent on a protein
component of the LDL interacting with a receptor on the
cells, the strategy required that the movement of the
particle be measured. Choices 1, 3, and 4 are all
incorrect because the addition of the radioactive label has
no impact on the solubility or metabolism of the LDL
particle nor does the addition of the label alter the protein
component of the LDL particle.
A minor criticism of the
scientist's strategy
employed for experiment 1 is
1. the method used for measuring the rate of
transport.
2. the use of an animal as a model for a
human disease.
3. the use of radioactivity, because it is
dangerous.
4. the injection of the LDL particle instead of
the ingestion through diet.
1
2
3
4
5
Explanation
 The correct answer is 4. The relation between coronary
heart disease and cholesterol is primarily due to high
consumption of cholesterol through the diet. Analysis of
cholesterol transport through the introduction of this
lipid directly into the bloodstream versus through the
digestive tract may not be the best experimental
strategy for understanding this relationship. Choice 1 is
incorrect, as it describes a valid method for measuring
the amount of a molecule. Choice 2 is incorrect, as it
describes the widely accepted use of animals as
models for humans. Choice 3 is incorrect since,
although radioactivity can be dangerous, it does not
invalidate the strategy employed by the scientist.
A major criticism of the
scientist's interpretation of
the result of experiment 1
is that
1.
measurement of radioactivity does not accurately
reveal the relative amount and, therefore, the rate, of
LDL in the blood.
variation in the rate of transport of the altered LDL is
controlled by a receptor molecule.
variation in the rate of transport of the altered LDL is a
result of the alteration of the protein component in the
particle.
there must be a comparison to unaltered LDL
transport rates.
2.
3.
4.
1
2
3
4
5
Explanation
 The correct answer is 2. The result reveals only that
changing the LDL protein component has an effect on
the rate of transport of the particle. It does not show
directly the presence of a receptor molecule and its
interaction with the protein. Choice 1 is incorrect, as
the use of a radioactive label is an accurate way to
measure the amount of LDL particle. Choice 3 is
incorrect, as this is exactly what the experiment
revealed. Choice 4 is incorrect because the passage
states, "The results of the experiment revealed that
when the LDL protein was altered, the LDL particles
remained in the blood much longer than particles with
an unaltered protein."
Based on the hypothesis, as
the radioactivity decreases
from the blood, it would
increase
1. in the fur of the animal.
2. in the body cells of the animal.
3. nowhere; the radioactivity would be
degraded.
4. in the lungs of the animal.
1
2
3
4
5
Explanation
 The correct answer is 2. This is because cholesterol is
used by cells in their membranes, in the production of
lipid hormones, or in the dispersion of fat during
digestion. Therefore, the cholesterol would leave the
blood and enter the cells by the transport mechanism
proposed in the hypothesis. Choices 1 and 4 are
incorrect because cholesterol does not play a role in fur
or lung tissue as described in the passage. Choice 3 is
incorrect because cellular processes will not degrade
the radioactivity: Radioactivity decays over a longer
time period than was covered by the experiment.
In support of the scientist's
interpretations of the result of
experiment 1, one would predict that
which of the following tissues would
exhibit the greatest number of
cholesterol receptors?
1.
2.
3.
4.
1
liver
adrenal glands
ovaries
all of the above
2
3
4
5
Explanation
 The correct answer is 4. The role of cholesterol
involves fat digestion in the liver (choice 1) and
lipid-like hormones, such as adrenaline and
estrogen, produced in the adrenal glands
(choice 2) and ovaries (choice 3), respectively.
If the hypothesis is correct, then the receptors
that mediate the transport of cholesterol of
these cell types should be quite abundant in
these tissues.
Graph 1 reveals that
1.
total cholesterol levels are reduced approximately 15fold more in individuals who were administered the
drug Cissus versus individuals who did not receive the
drug.
total cholesterol increased in subjects who did not
receive the drug Cissus in the experiment.
total cholesterol decreased at a faster rate in
individuals who received the drug Cissus versus those
who did not receive the drug.
no change in cholesterol levels was observed in any
test subjects.
2.
3.
4.
1
2
3
4
5
Explanation
 The correct answer is 1. The graph plots the
percentage of total cholesterol measured after six
weeks in individuals who received the drug Cissus
versus those who received no drug (but did receive a
placebo). As the y-axis exhibits negative percentage
intervals the bar size corresponds to the extent of
decrease in cholesterol levels. Those subjects who
received Cissus exhibited a reduction in cholesterol by
11.6%. Those who received a placebo exhibited a
decrease of 0.7% (15-fold difference). Choice 3 is
incorrect because the graph does not reveal changes
over time, which would indicate rate.
What does Graph 2 state
about the source of blood
cholesterol?
1. LDL particles are the only source of total
blood cholesterol.
2. LDL particles are a major but not sole source
of total blood cholesterol.
3. LDL particles do not contribute to total blood
cholesterol levels.
4. The graph does not reveal any meaningful
data about the source of blood cholesterol.
1
2
3
4
5
Explanation
 The correct answer is 2. Graph 2 reveals that
LDL levels are at 2% in those test subjects
NOT given the drug Cissus. Graph 1 reveals
that there was a reduction in total cholesterol
levels in those subjects. There must be another
component contributing to blood cholesterol
levels to account for this variation in total
versus LDL levels in test subjects. Choice 4 is
incorrect because the graph clearly shows a
reduction in blood LDL cholesterol levels of
9.3% in those subjects taking Cissus.
The scientist concluded the drug is
effective in controlling total
cholesterol levels. This means that
1. high HDL levels in the blood may
contribute to a reduction in total blood
cholesterol.
2. low HDL levels in the blood contribute to
an increase in total blood cholesterol.
3. high LDL levels contribute to a reduction in
total blood cholesterol.
4. HDL levels increase when LDL levels
increase.
1
2
3
4
5
Explanation
 The correct answer is 1. The HDL levels of test
subjects receiving the drug Cissus increased
approximately 17-fold over those subjects who did not
receive the drug (Graph 3). This increase, coupled with
the concomitant decrease of total and LDL associated
cholesterol in Graphs 1 and 2, along with the scientist
interpretation that the drug was effective, indicates that
high HDL levels correlate with low blood cholesterol
levels. Choice 4 is incorrect because Graphs 1 and 3
reveal a decrease in LDL and an increase in HDL in
response to administration of the drug Cissus.
Please read Science 9
Which of the two hypotheses
should be rejected based on
the evidence described?
1. hypothesis 1
2. hypothesis 2
3. Neither hypothesis should be
rejected.
4. Both hypotheses should be rejected.
1
2
3
4
5
Explanation
 The correct answer is 3. Because there
is a single line of evidence, the iridium
layer of sediment, which supports both
statements, neither can be rejected at
this point.
What type of evidence would allow
for the acceptance of hypothesis 2?
1. identification of a large crater resulting from an
asteroid impact occurring approximately 65
million years ago
2. no evidence of a large crater resulting from an
asteroid impact occurring approximately 65
million years ago
3. the remains of extensive lava flows dating
back to 65 million years ago
4. no evidence for lava flows dating back to 65
million years ago
Explanation
 The correct answer is 3. Lava flow results from
volcanic eruptions; an extensive lava flow
dating to the time of the mass extinction would
support volcanic eruptions (hypothesis 2) more
than asteroid impacts (hypothesis 1). Choice 2
is not correct, as the lack of evidence for one
hypothesis (asteroid impact) does not lend
support to the competing hypothesis (volcanic
eruption). Choice 1 is incorrect, as it provides
solid evidence in support of hypothesis 1
(asteroid impact). Choice 4 is incorrect, and it
provides no evidence in support of hypothesis
2.
The recently uncovered
evidence discussed in
passage 2 lends support to
1.
2.
3.
4.
1
hypothesis 1.
hypothesis 2.
neither hypothesis.
both hypotheses.
2
3
4
5
Explanation
 The correct answer is 4. Both the quartz
grains and the lava flows, along with the
iridium layer, lend strong support to both
an asteroid impact and volcanic activity.
This evidence does not result in the
rejection of either hypothesis, but it does
lead to the acceptance of both
hypotheses and the need for further
testing.
The discovery of additional
evidence supporting both
hypotheses allows which of the
following conclusions to be drawn?
1.
Both events occurred approximately 65 million
years ago, leading to global climate change and a
mass extinction.
A massive asteroid impacted first, which led to
extensive volcanic eruptions and the resulting mass
extinction.
The iridium deposition was the result of both
asteroid impact and volcanic eruptions occurring 65
million years ago.
all of the above
2.
3.
4.
1
2
3
4
5
Explanation
 The correct answer is 4. All three
statements (1, 2, and 3) can be
conclusions drawn based on all the
evidence assembled. Both events could
have occurred simultaneously (choice 1)
or one event could have spurred the
second event (choice 2), which would
result in the deposit of iridium (choice 3)
among the other evidence identified.
Please read Science 10
Graph A demonstrates
1. the length of the light waves absorbed by
chlorophyll.
2. the ultraviolet portion of the
electromagnetic spectrum absorbed by
chlorophyll.
3. the extent to which chlorophyll absorbs
light of all wavelengths in the
electromagnetic spectrum.
4. nothing conclusive about chlorophyll.
1
2
3
4
5
Explanation
 The correct answer is 1. The graph plots the
amount of light energy absorbed (y-axis) by
chlorophyll against the wavelength of the light
(x-axis). A portion of the electromagnetic
spectrum is plotted on the x-axis. Choices 2
and 3 are incorrect because the graph shows
only the visible portion of the electromagnetic
spectrum. Choice 4 is incorrect because the
graph clearly shows the specific wavelengths
of visible light that chlorophyll absorbs.
Chlorophyll exhibits the
greatest absorption of light
of
1.
2.
3.
4.
1
high energy.
low energy.
equal energy.
You cannot determine the energy
content of light from this graph.
2
3
4
5
Explanation
 The correct answer is 1. Energy content of light
is inversely proportional to its wavelength. The
graph demonstrates that chlorophyll absorbs
more light of the higher energy, shorter
wavelength (400–450 nm) versus the lower
energy light of the longer wavelength (650–700
nm). Choice 4 is incorrect because the
wavelength of light reveals the relative energy
the light possesses.
A scientist wants to measure the
photosynthetic activity of the
common aquatic plant Elodea
under various growth conditions. A
good indicator of photosynthetic
activity would be
1. the amount of carbon dioxide
produced.
2. the amount of oxygen produced.
3. the amount of water produced.
4. the rate of stem/leaf growth.
1
2
3
4
5
Explanation
 The correct answer is 2. Photosynthesis is the
process by which a cell uses light energy to
convert water and carbon dioxide to oxygen
and sugar. The amount of product should
indicate the activity of the process of
photosynthesis. Choices 1 and 3 are incorrect
because these are the building blocks for the
photosynthetic process, not the products.
Choice 4 is incorrect because many factors
contribute to the rate of stem/leaf growth. This
is not a direct measure of photosynthetic
activity.
Please read Science 11
Which of the following
conclusion(s) can be drawn
from the data in Table A?
1. A.The lower the pH, the greater the
photosynthetic activity.
2. The higher the pH, the more oxygen is
generated.
3. Increased acidity leads to a reduction in
photosynthetic activity.
4. Carbon dioxide uptake is not indicative of
photosynthetic activity.
1
2
3
4
5
Explanation
 The correct answer is 1. Photosynthesis is the process
by which a cell uses light energy to convert water and
carbon dioxide to oxygen and sugar. The amount of
product should indicate the activity of the process of
photosynthesis. At pH 5, the amount of oxygen
generated is 5-fold greater than at pH 7. Choice 2 is
incorrect because the oxygen production decreases
with increasing pH. Choice 3 is incorrect because
increased acidity means a decrease in pH; and
decrease in pH facilitates oxygen generation, thereby
reflecting increased photosynthetic activity. Choice 4 is
incorrect because photosynthesis is the process by
which a cell uses light energy to convert water and
carbon dioxide to oxygen and sugar. This definition
requires that carbon dioxide be used for the process;
therefore, carbon dioxide uptake is indicative of
photosynthetic activity, in this experiment.
Based on the results
reported in Table A, the rate
of photosynthesis is limited
by
1. A.the amount of oxygen available.
2. the amount of hydrogen ion
available.
3. the amount of carbon dioxide
available.
4. an acidic environment.
1
2
3
4
5
Explanation
 The correct answer is 3. The mols of oxygen generated
during the photosynthetic event are directly
proportional to the mols of carbon dioxide available,
regardless of pH. Photosynthesis is the process by
which a cell uses light energy to convert water and
carbon dioxide to oxygen and sugar. Choice 1 is
incorrect because oxygen is a product of
photosynthesis. Choice 2 is incorrect because although
pH and, therefore, hydrogen ion concentration, has an
affect on the overall rate of photosynthesis, the
reaction is still limited to the amount of carbon dioxide
available (see direct relationship between mols of
carbon dioxide relative to mols of oxygen at each pH).
Choice 4 is incorrect because an acidic environment is
the direct result of hydrogen ion concentrations.
Please read Science 12
The results of this graph can
be described in which of the
following way(s)?
1. Oxygen levels are decreasing as the sugar
levels decrease.
2. Carbon dioxide levels are decreasing as
the sugar levels decrease.
3. The amount of sugar available has no
impact on carbon dioxide production.
4. Carbon dioxide levels are increasing with
increasing sugar levels.
1
2
3
4
5
Explanation
 The correct answer is 1. Sugar levels are decreasing
with increasing time (x-axis). As time progresses,
oxygen levels are decreasing and carbon dioxide
levels are increasing (y-axis). This also demonstrates
that the amount of sugar available (less with increasing
time, x-axis) impacts the amount of carbon dioxide
generated (y-axis). Choices 2 and 4 are incorrect
because carbon dioxide levels are increasing as sugar
levels are decreasing over time. Choice 3 is incorrect
because the graph clearly shows that the amount of
sugar available (less with increasing time, x-axis)
impacts the amount of carbon dioxide generated (more
with increasing time, y-axis).
What conclusion(s) can be
drawn from the
interpretation of these
results?
1. The reverse reaction of photosynthesis
must be occurring.
2. A plant will use carbon dioxide instead of
oxygen to make sugars.
3. Not enough time passed to draw a
conclusion.
4. Under low oxygen conditions, sugar can
still be generated by this plant.
1
2
3
4
5
Explanation
 The correct answer is 1. The graph illustrates the
reverse reaction of photosynthesis. Photosynthesis is
the process by which a cell uses light energy to convert
water and carbon dioxide to oxygen and sugar. In this
experiment, the products of photosynthesis (sugar and
oxygen) were made available to Elodea. The resulting
production of carbon dioxide and the depletion of
oxygen as sugar levels decrease support this
conclusion. Choice 2 is incorrect, as there is no sugar
being produced and carbon dioxide levels are
increasing. Choice 3 is incorrect because the graphs
generated are smooth and without outliers. An
additional experiment conducted for a longer time
period may generate new data; however, based on this
graph, this statement that "not enough time passed to
draw a conclusion" is invalid. Choice 4 is incorrect
because there is no data demonstrating an increase in
sugar over the course of the experiment.
The scientist repeated the
previous experiment (question 18)
in the absence of light. The results
obtained were identical to those
plotted in Graph B. These results
1. indicate that the reverse reaction of
photosynthesis can occur in the absence
of light.
2. are an anomaly.
3. refute the data obtained in the first
experiment (Graph B).
4. do not provide any new data.
1
2
3
4
5
Explanation
 The correct answer is 1. These data are in agreement
with the data obtained under all of the same conditions
except the presence of light (Graph B). Photosynthesis
is the process by which a cell uses light energy to
convert water and carbon dioxide to oxygen and sugar.
In this experiment, the products of photosynthesis
(sugar and oxygen) were made available to Elodea.
The resulting production of carbon dioxide and the
depletion of oxygen as sugar levels decrease support
this conclusion. Choice 2 is incorrect as there is no
basis to assume that these data are faulty. Choice 3 is
incorrect because these data agree with the data
represented in Graph B; therefore, the data is not
refuted but supported. Choice 4 is incorrect because
the results do provide new data as the data were
generated in the absence of light (a new variable,
generating new data).