Summary
Some anticancer drugs work by depriving tumors of needed blood vessels. The drugs work by prohibiting angiogenesis, which is the creation of blood vessels. The same drugs have been discovered to prevent obesity in rodents.
Strongly Supported Conclusions
Angiogenesis is necessary for fat cells to grow.
A
The cells in tumors are more similar in structure to fat cells than to other cells in the body.
This answer is unsupported. We don’t know what the structure is of any kind of cell.
B
Drugs that inhibit angiogenesis would probably enable obese humans to lose weight.
This answer is unsupported. We don’t know if these drugs would probably cause obese humans to lose weight. We only know that the drugs have been found to prevent obesity in rodents.
C
Fat tissue depends on angiogenesis in order to grow.
This answer is strongly supported. Since the drugs prevent obesity in rodents, the drugs probably do this by inhibiting angiogenesis.
D
Rodents with cancer are more likely to be obese than healthy rodents.
This answer is unsupported. We don’t know anything about rodents with cancer.
E
Drugs that inhibit angiogenesis also prevent absorption of vital nutrients.
This answer is unsupported. We don’t know if the drugs have any other effects besides inhibiting angiogenesis.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that the oil crisis of 1973 was due to collusion between oil companies and oil-producing countries. This is based on the fact that after 1973, the profits of oil companies increased, and the incomes of oil-producing companies also increased.
Identify and Describe Flaw
The author assumes that because oil companies and oil-producing countries benefited from the oil crisis, that they must have played a role in causing the oil crisis. This overlooks the possibility that they simply benefited from an event that they did not cause.
A
fails to consider the possibility that a party can benefit from an event without helping to bring about that event
This possibility shows why the conclusion doesn’t follow from the premises. If something can benefit from an event without helping to cause it, then the fact certain companies and countries benefited from the oil crisis does not prove that they caused it.
B
presumes, without providing justification, that oil companies and oil-producing countries were the only parties to benefit from the 1973 oil crisis
If other parties benefited, too, that doesn’t undermine the argument’s reasoning. The author might believe those other parties were also contributory factors in the oil crisis of 1973.
C
rests on using the term “profit” in an ambiguous way
The word “profit” is not used to mean two different things. “Profit” is used to mean financial gain.
D
fails to establish that there was a worldwide oil surplus prior to the crisis of 1973
There is no need to establish that there was a surplus in order to show that certain parties caused a reduction in available oil later.
E
fails to consider the possibility that events that occur simultaneously can be causally related
The author doesn’t overlook this possibility. In fact, the author’s conclusion assumes that the increased profits and income of oil companies and oil-producing countries are causally related to each other.
"Surprising" Phenomenon
Despite having high radiation levels, wildlife populations around Chernobyl have expanded rapidly.
Objective
The right answer will be a hypothesis that explains why wildlife populations expanded after the Chernobyl accident, despite the high levels of radiation wildlife populations have. This explanation must result in population increases being a likely outcome given the circumstances after the accident. These circumstances must outweigh the negative effects of the radiation.
A
Animals that did not arrive in the area around the Chernobyl nuclear plant until after the accident still developed high levels of radiation in their muscles and bones.
We need to know why these animals were still able to proliferate despite high levels of radiation. This doesn’t offer an explanation for that peculiar phenomenon.
B
Some of the species that inhabit the region are migratory and so only live in the region for part of the year, limiting their exposure to the radiation.
The stimulus tells us that wildlife populations generally have high levels of radiation. We’re not interested in a few outliers.
C
The region affected by the release of radiation is very large, encompassing 1,800 square miles (4,660 square kilometers).
All this says is that lots of wildlife populations were likely affected by the radiation. We need to know why their populations expanded.
D
While some of the radioactive chemicals released by the accident depress fertility in local birds, others do not.
Like (B), “some” signifies an outlier. We need to know why wildlife populations in general expanded despite having high levels of radiation.
E
The threat of radiation poisoning drove people out of the area, which opened up new habitat for wildlife and eliminated the danger from hunters.
Though radiation may be a threat in itself, wildlife populations were generally safer after Chernobyl. For one thing, they had a larger habitat since humans had to leave. For another, there were no more hunters around. This explains why their populations increased.
Summarize Argument
The author concludes that we should be skeptical when geneticists say that personality traits that aren’t thought to be genetically determined actually are genetically determined. The author supports this conclusion with the subsidiary conclusion that the geneticists are probably amplifying their own importance when they make such a claim. This sub-conclusion is supported by the fact that specialists tend to see their own specialties as important.
Identify and Describe Flaw
The author attacks the motivation of the geneticists rather than the substance of their claim. The motivation of the geneticists in making their claim that certain traits are genetically determined has no bearing on the truth of that claim.
A
generalizes about all specialists on the basis of an unrepresentative sample
The conclusion is just about geneticists. So it doesn’t generalize about all specialists.
B
presumes that the traditional view must be the right view simply because it is what has been traditionally believed
The author’s conclusion is not based merely on the fact that a particular view has been the traditional belief. The conclusion is based on comments on the motivation of the geneticists.
C
draws a conclusion that is merely a restatement of one of its main premises
(C) describes circular reasoning. The author’s conclusion — which asserts that we should be skeptical of a certain claim — is not restated in the premises, which concern the motivation of geneticists.
D
appeals to the authority of those unlikely to be well informed about the topic at issue
The author’s reasoning is not based on an appeal to authority. The author does not say that we should reject a belief because certain authorities reject it.
E
disputes a claim on the basis of a supposed motive for making the claim rather than by assessing the evidence relevant to the claim
The author disputes the geneticists’ claim based on the geneticists’ supposed motivation in making that claim (the desire to amplify their own importance). This is flawed because their motivation doesn’t relate to the truth of their claim.
"Surprising" Phenomenon
Toning shoes don’t exercise leg muscles more than regular shoes, yet most people who switch to toning shoes experience a strengthening of their leg muscles.
Objective
The correct answer will be a hypothesis that explains a key difference between toning shoes and regular shoes, beyond the actual exercise the shoes afford. This difference likely rests in who wears the shoes. People may, for example, experience a strengthening of their leg muscles after switching to toning shoes because they’re making a concerted effort to get exercise.
A
Toning shoes strengthen small underused muscles in the feet and ankles.
We’re concerned with how major leg muscles are strengthened.
B
Muscles in the leg adapt to the rounded shape of toning shoes almost immediately.
This reinforces the idea that toning shoes provide no exercise benefit. We need to know why people who switch to them get a benefit, anway.
C
Many people find toning shoes especially comfortable and walk more as a result.
True, toning shoes don’t have any real exercise advantage over regular shoes. But people who switch to toning shoes end up walking more, which certainly exercises their leg muscles. This explains how they get a benefit from toning shoes.
D
There is little evidence that toning shoes cause injuries to their wearers.
Our stimulus says nothing about injuries. We need to know why people who switch to toning shoes get a benefit.
E
Shoes that strengthen the major leg muscles are more marketable than ordinary shoes.
Toning shoes don’t themselves strengthen the major leg muscles.
Summary
Rodents are small mammals that have chisel-like incisor teeth. Most individual mammals in North America are rodents, even though most mammal species in North America are not rodents.
Strongly Supported Conclusions
In North America, rodent species usually have more individual members than other species of mammals.
A
Most species of North American mammals have chisel-like incisor teeth.
This answer is unsupported. The stimulus only tells us of one example of a species of mammal that has chisel-like incisor teeth. To say that most mammal species have these teeth is too extreme.
B
In North America, rodent species tend to have more individual members than other species of mammals have.
This answer is strongly supported. We know from the stimulus that most individual mammals in North America are rodents. Therefore, rodent species tend to have more individual member than mammal species that are not rodents.
C
Most species of mammals that have chisel-like incisor teeth can be found in North America.
This answer is unsupported. The stimulus only tells us of one example of a species of mammal in North America that has chisel-like incisor teeth. We cannot assume that there are other species with similar teeth from the stimulus.
D
Of the mammal species in North America, the one with the most individual members is a species of rodent.
This answer is unsupported. We don’t know from the stimulus how many species of rodent exist, and we don’t know how many individual members exist within each potential species of rodent to make this claim.
E
Most nonrodent mammal species can be found in North America.
This answer is unsupported. We don’t have any information in the stimulus about mammal species existing outside of North America to make this comparison.
Summarize Argument
The author concludes that Patricia’s garden will be productive. This is based on the fact that if a garden doesn’t have lots of water and sunlight, and isn’t planted in rich soil, it won’t be productive. However, Patricia’s garden will have lots of water and sunlight and will have rich soil.
Identify and Describe Flaw
The author confuses sufficient and necessary conditions. We know that having lots of sunlight and water, and rich soil are necessary for a garden to be productive. But this doesn’t imply that possessing these qualities is sufficient to make a garden productive. A garden might still be unproductive even if it has lots of water and sunlight and rich soil.
A
fails to specify adequately the meaning in context of the term “ideal”
The failure to specify the exact meaning of “ideal” is not what makes the argument flawed. “Ideal” has its own meaning, and we can simply interpret the word using its dictionary definition.
B
infers a cause from a correlation
The argument does not assume correlation proves cause. There is no causal relationship being concluded or assumed. The author simply believes Patricia’s garden will be productive because it has certain necessary conditions for being productive.
C
confuses a cause with its effect
There is no causal relationship being concluded or assumed. The author simply believes Patricia’s garden will be productive because it has certain necessary conditions for being productive.
D
takes a set of necessary conditions as sufficient
The first premise establishes that water, sunlight, and rich soil are necessary for a garden to be productive. But the author mistakenly thinks those qualities are sufficient to guarantee that a garden will be productive.
E
relies on a sample that is unlikely to be representative
The author doesn’t rely on a sample. We get a premise about Patricia’s garden, and the conclusion is about that same garden.
Summarize Argument
The author concludes that there must be a lake of liquid water between Enceladus’s rocky core and icy surface. This is because a space probe discovered something denser than ice between the core and the surface, and that denser substance can only be liquid water.
Identify Conclusion
The conclusion is the assertion that there’s a lake of liquid water between Enceladus’s rocky core and icy surface: “Between these two layers, there must be a lake of liquid water.”
A
Saturn’s moon Enceladus has a rocky core and an icy surface.
This is context. The author’s conclusion concerns what must be in between those two layers.
B
There must be a lake of liquid water between the rocky core and the icy surface of Enceladus.
This is a restatement of the second sentence, which is the conclusion.
C
The Cassini space probe was used to measure the density of Enceladus.
This is part of the support. The author concludes that there must be a lake of liquid water based on what this probe found.
D
Density measurements reveal something denser than ice between the core and surface of Enceladus.
This is part of the support. The author concludes that there must be a lake of liquid water based on these measurements.
E
Anything denser than ice between the core and surface of Enceladus would have to be liquid water.
This is part of the support. Because the denser substance could only be water, the author concludes that a lake of liquid water must exist between the rocky core and icy surface.
Summary
Seasonal allergy symptoms are the immune system's response to pollen in the air. When a large amount of pollen is inhaled, it can trigger allergy symptoms. While there are medications to suppress these symptoms, a more effective strategy is to stay indoors during dry, windy days during allergy season.
Strongly Supported Conclusions
Staying inside reduces allergy symptoms and limits the amount of pollen one inhales.
A
Medicines that minimize seasonal allergy symptoms prevent people from inhaling large amounts of pollen.
There is no support that these medicines prevent people from inhaling pollen. The stimulus only says that they minimize symptoms
B
Most types of pollen do not cause seasonal allergy symptoms.
There is no support for what “most” types of pollen do or don’t do.
C
People who stay indoors on dry, windy days during allergy season are unlikely to inhale large amounts of pollen.
The stimulus says that staying indoors is a more effective strategy to minimize allergy symptoms. Allergy symptoms are caused by inhaling large amounts of pollen. It is not unreasonable to assume that staying indoors makes this unlikely.
D
People who take medicines that minimize seasonal allergy symptoms tend to stay indoors on dry, windy days during allergy season.
The stimulus only says that medicines limit symptoms. There is no link between medicine and staying indoors.
E
People who experience seasonal allergy symptoms typically use air filters that remove pollen from the air in their homes.
This is not supported because there is no mention of air filters at all within the stimulus.