"Surprising" Phenomenon
The group using mite-proof bedding reported no reduction in allergy symptoms despite the fact that the dust-mite allergens in their mattresses decreased by 69%.
Objective
The right answer will either show how a 69% reduction in mattress dust-mite allergens could have no impact on people’s symptoms, or explain that the participants’ reports inaccurately downplayed a symptom reduction that did occur.
A
Dust-mite allergens in bedding tend to irritate many allergy sufferers’ nasal passages more than do the same allergens in other locations, such as carpets.
This does the opposite of what we need. If bedding tends to be the dust-mite location that most irritates allergy sufferers, we would expect a 69% reduction in mattress allergens to lead to a decrease in allergy symptoms. We want something that shows why that didn’t happen here.
B
When people report their own allergy symptoms, they tend to exaggerate the severity of those symptoms.
Even if the allergy sufferers exaggerated the severity of their symptoms, they would have done so both before and after the study, meaning we would still expect the reports to show a change due to the decreased allergen exposure. This answer doesn’t explain why that didn’t occur.
C
The medical community does not fully understand how dust-mite allergens cause allergy.
In order for this to be the right answer, we would need some indication that the information the medical community is missing would explain why the allergy sufferers in the experiment did not experience a reduction in symptoms. Because this doesn’t give us that, it’s not helpful.
D
For dust-mite allergy sufferers to get relief from their allergies, dust-mite allergens must be reduced by 90 to 95 percent.
This explains why the participants in the study did not experience a reduction in their allergy symptoms: their exposure to allergens did not decrease enough to lead to symptom relief.
E
All of the participants in the study were told that one group in the study would be sleeping on mite-proof bedding.
This doesn’t help us. Many studies are structured this way; as long as participants are unaware of which group they are in, we wouldn’t expect a placebo effect to skew the reports of allergy symptoms.
Summary
One way to compare chess-playing programs is to compare how they perform a fixed time limit per move. This comparison is done by using any two computers that can run the program and giving each computer a set time limit to make a move. The faster computer will have a better chance of winning because the program can examine more moves within the same span of time and pick the best possible move.
Strongly Supported Conclusions
If two computers are running the same chess-playing software, the computer that can analyze the most available moves within a given time limit is most likely to win.
A
If one chess-playing program can examine more possible moves than a different chess-playing program run on the same computer under the same time constraints per move, the former program will have a better chance of winning than the latter.
This sounds similar but presents a very different situation. This talks about two *different* programs running on the *same* computer. If there were two different programs, there would be many more confounding variables to make a comparison.
B
How fast a given computer is has no effect on which chess-playing computer programs can run on that computer.
The stimulus says that the speed of a computer dictates how many moves the computer can assess, but nothing says its speed has no bearing on what program it can run. For example, you probably couldn’t run a fancy program on a potato computer.
C
In general, the more moves a given chess-playing program is able to examine under given time constraints per move, the better the chances that program will win.
This captures exactly what the stimulus details. The faster computer can examine more moves and is thus better positioned to make better moves and win.
D
If two different chess-playing programs are running on two different computers under the same time constraints per move, the program running on the faster computer will be able to examine more possible moves in the time allotted.
This is a very different scenario than the stimulus. This answer choice has two different computers and two different programs. You can only reach the same conclusion under the same conditions presented in the stimulus.
E
If a chess-playing program is run on two different computers and is allotted more time to examine possible moves when running on the slow computer than when running on the fast computer, it will have an equal chance of winning on either computer.
There is no information on what would happen if a slower computer was given more time compared to a faster computer. You have to assume that the processing speed of the slower computer is exactly equal to the time difference given to the faster computer.
Summarize Argument
The politician argues that it would harm democracy if a government were to monitor conversations. Why? Because for a democracy to work, people need to be able to freely share their ideas without worrying the government might take action against them. Unmonitored private conversations are essential to democracy.
Identify Argument Part
The referenced text supports the second sentence, which in turn supports the conclusion. Why is the right to private, unmonitored conversations essential to democracy? Because democracy requires free expression of ideas.
A
It is a claim for which no support is provided, and which is used to support only the argument’s main conclusion.
There’s certainly no support provided for the referenced text, but it doesn’t support the main conclusion. Instead, it supports a sub-conclusion, which in turn supports the main conclusion.
B
It is a claim for which no support is provided, and which is used to support a claim that is itself used to support the argument’s main conclusion.
The referenced text is definitely unsupported, which makes it a premise. It supports the second sentence, which in turn supports the main conclusion about democracy being harmed when the government monitors conversations.
C
It is a claim for which support is provided, and which is in turn used to support the argument’s main conclusion.
There’s no support for this claim. Nor does it support the main conclusion. Instead, it’s support for a sub-conclusion.
D
It is the argument’s main conclusion and is inferred from two other statements in the argument, one of which is used to support the other.
The argument’s main conclusion is the last sentence. The referenced text certainly isn’t inferred from the sub-conclusion and main conclusion.
E
It is the argument’s main conclusion and is inferred from two other statements in the argument, neither of which is used to support the other.
The referenced text isn’t the main conclusion. It also isn’t inferred from anything. It’s support for the second sentence, which is a sub-conclusion.
The diet of Heliothis subflexa caterpillars consists entirely of fruit from plants of the genus Physalis. These fruit do not contain linolenic acid, which is necessary to the growth and maturation of many insects other than H. subflexa. Linolenic acid in an insect’s diet is also necessary for the production of a chemical called volicitin. While most caterpillar species have volicitin in their saliva, H. subflexa does not.
Summary
Most caterpillar species have volicitin in their saliva.
If an insect produces volicitin, then it must have linolenic acid in its diet.
Many insects need linolenic acid to grow.
*Physalis* plants don’t contain linolenic acid.
*H. subflexa* caterpillars only eat *Physalis* plants.
*H. subflexa* caterpillars don’t have volicitin in their saliva.
Very Strongly Supported Conclusions
Most caterpillar species have linolenic acid in their diets.
Most caterpillar species don’t eat only *Physalis* plants.
Many insects can’t grow and mature if they only eat *Physalis* plants.
A
H. subflexa caterpillars synthesize linolenic acid within their bodies.
Unsupported. *H. subflexa* caterpillars don’t get linolenic acid from their diets, but this doesn’t necessarily mean that they synthesize it within their bodies. They might just not need any linolenic acid or volicitin.
B
Most species of caterpillar have sources of linolenic acid in their diets.
Very strongly supported. Most species of caterpillar have volicitin in their saliva. And if an insect produces volicitin, then it must have linolenic acid in its diet. So most species of caterpillar have linolenic acid in their diets.
C
Any caterpillar that has linolenic acid in its diet has volicitin in its saliva.
Unsupported. If a caterpillar has volicitin in its saliva, then it must have linolenic acid in its diet. But this doesn’t necessarily mean that if a caterpillar has linolenic acid in its diet, then it must have volicitin in its saliva. (C) reverses the conditional claim.
D
A food source containing linolenic acid would be poisonous to H. subflexa caterpillars.
Unsupported. *H. subflexa* caterpillars only eat plants that don’t contain linolenic acid. But this doesn’t necessarily mean that plants that do contain linolenic acid are poisonous to them. They might just hatch on *Physalis* plants and never move to other plants.
E
No caterpillars other than H. subflexa eat fruit from plants of the genus Physalis.
Unsupported. Most caterpillars have linolenic acid in their diets. But this doesn’t mean that no other caterpillars eat *Physalis* plants. There might be others like *H. subflexa* that only eat *Physalis* plants, or some that eat *Physalis* plants and other plants with linolenic acid.
Summarize Argument
The author concludes that the hepadnavirus present in the chromosomes of a zebra finch and dark-eyeed junco is at least 25 million years old. This is because after a hepadnavirus inserts itself into a chromosome of an animal, it’s based on to all of that animal’s descendants. In addition, the hepadnavirus is found in the same location in the corresponding chromosome of the finch and the junco. And, these two species diverged around 25 million years ago.
Notable Assumptions
The author assumes that having a hepadnavirus in the same corresponding location in the chromosome tells us something about when the hepadnavirus was inserted. The author also assumes the hepadnavirus didn’t insert itself into each bird’s chromosome more recently than 25 million years ago.
A
Viruses can affect the evolution of an organism and can thereby influence the likelihood of their diverging into two species.
This suggests viruses might have influenced the divergence of the two species. But this doesn’t suggest anything about the age of the hepadnavirus. Perhaps other viruses caused the species to diverge, and the hepadnavirus was inserted in each chromosome after divergence.
B
The chromosomes of the zebra finch and the dark-eyed junco contain fragments of no virus other than the hepadnavirus.
This tells us there’s no other virus in the chromosomes of the birds. But this doesn’t reveal anything about the age of the hepadnavirus.
C
When a virus inserts itself into an animal’s chromosome, the insertion occurs at a random spot.
This strengthens by casting doubt on the possibility that the virus inserted itself into each chromosome after the divergence 25 million years ago.
D
Many bird species other than the zebra finch and the dark-eyed junco contain fragments of the hepadnavirus.
The presence of the virus in other birds has no clear impact on how long the virus has been around.
E
The presence of a hepadnavirus in an animal species does not affect the likelihood of that species’ survival.
Whether the virus affects chances of a species’ survival has no clear impact on how long the virus has been around.