One adaptation that enables an animal species to survive despite predation by other species is effective camouflage. Yet some prey species with few or no other adaptations to counteract predation have endured for a long time with black-and-white coloration that seems unlikely to provide effective camouflage.

"Surprising" Phenomenon
How have some black-and-white prey species survived despite the fact that they have few or no adaptations to counteract predation and their coloration seems unlikely to provide effective camouflage?

Objective
The right answer will describe some factor that has allowed the black-and-white species to endure for a long time, despite their apparent survival shortcomings. This might take the form of explaining how the coloration actually does benefit the species despite what we may think, adding some additional survival information about these species, or showing some weakness in the species’ predators.

A
Most species with black-and-white coloration are more populous than the species that prey upon them.
This doesn’t matter. We expect that predators eat more than one animal throughout their lives, so the prey species being more populous doesn’t explain their survival. This answer also doesn’t say how much more populous the prey are—it could be that there’s only one more of them!
B
No form of camouflage is completely effective against all kinds of predators.
This doesn’t help. The black-and-white species in question seem not to have any camouflage at all, so general information about camouflage effectiveness isn’t relevant or useful.
C
Animals of many predatory species do not perceive color or pattern in the same manner as humans do.
This explains how the black-and-white coloration that humans don’t see as effective camouflage might in fact function as such against predator species. Maybe these predators see the world in black-and-white or perceive patterns that match the prey’s coloration!
D
Conspicuous black-and-white areas help animals of the same species avoid encounters with one another.
This isn’t helpful. We need information about how these black-and-white animals evade predator species in order to survive, not how they avoid one another.
E
Black-and-white coloration is not as great a liability against predators at night as it is during the day.
This doesn’t matter. This answer choice suggests that black-and-white coloration is a liability against predators, even if that liability is less substantial at night!

Extracurricular


76 comments

Philosopher: A person is morally responsible for an action only if that action is performed freely. And an action is free only if there is an alternative action that is genuinely open to the person. But an alternative action is genuinely open only if performing that alternative action is not morally wrong.

Summary

The stimulus can be diagrammed as follows:

Notable Valid Inferences

If someone is morally responsible for an action, then it is not the case that the alternative to that action is morally wrong.

If an action was performed freely, then it is not the case that the alternative to that action is morally wrong.

If someone is morally responsible for an action, then there is an alternative action that is genuinely open to the person.

A
An alternative action is not genuinely open to a person unless that person would be morally responsible for performing the alternative action.

Could be false. We know that moral responsibility is a sufficient condition for an alternative action being genuinely open; (A) mixes up the sufficient and necessary conditions of this relationship.

B
People are not morally responsible for most of the actions that they perform.

Could be false. The stimulus does not discuss any quantities; we cannot make any inferences about “most” actions that people perform.

C
A person is morally responsible for an action if there is an alternative action that is genuinely open to the person.

Could be false. We know that moral responsibility is a sufficient condition for an alternative action being genuinely open. Like (A), (C) mixes up the sufficient and necessary conditions of this relationship.

D
If it would be morally wrong for a person to perform a given action, then that action is genuinely open to that person.

Could be false. We know that if an alternative action is morally wrong, then that alternative action was not genuinely open. (D) misses the fact that this relationship discusses “alternative” actions. Also, the necessary condition is that the action is not genuinely open.

E
An action is not free unless there is an alternative action that is not morally wrong.

Must be true. As shown below, an action being performed freely is a sufficient condition for the alternative to that action not being morally wrong.


15 comments

Nuts are high in calories. All else being equal, the more calories one consumes, the more likely one is to become overweight. However, studies have found that people who eat nuts regularly are actually less likely to be overweight than people who never eat nuts.

"Surprising" Phenomenon
Nuts are high in calories, yet people who eat nuts are less likely to be overweight than people who never eat nuts.

Objective
The correct answer will be a hypothesis that explains how people consuming a certain high-calorie food can gain less weight than those not consuming that high-calorie food. The explanation must result in nut-eaters mitigating their caloric intake with diet and/or exercise, or else result in the people who never eat nuts eating a higher-calorie diet overall.

A
The likelihood of becoming overweight depends not only on how many calories one consumes but also on how rapidly one burns those calories through physical activity.
This seems like a component of the explanation we’re looking for. However, we need to know that the nut-eaters are actually getting more physical activity.
B
Due to the fact that nuts are rich in calories, consuming a sufficiently large quantity produces a feeling of satiation.
This is missing a comparative aspect. How do we know the people who never eat nuts aren’t reaching the same feeling satiation on lower-calorie foods?
C
If people who avoid a certain kind of food are more likely to be overweight than people who consume that food regularly, then that food should not be avoided for weight loss purposes.
It doesn’t matter whether a food should or shouldn’t be avoided. We need to know why eating high-calorie nuts seems to be beneficial for preventing unhealthy weight gain.
D
On average, people who never eat nuts consume the same total calories per day as people who regularly eat nuts.
If both groups are eating the same amount of calories, then why are the nut-eaters less likely to be overweight? We need more information on how the two groups differ, rather than how they’re similar.
E
Most people who regularly eat nuts eat correspondingly less of foods whose taste, unlike that of nuts, stimulates a hunger response.
People who ate nuts were satisfied after eating. People who didn’t eat nuts ate food that made them think they were hungry, which led to overeating. This explains why eating nuts proved beneficial for preventing weight gain in the study.

15 comments

Newspaper: Increases in produce prices apparently have led to an increase in the planting of personal gardens. The two largest retail seed companies each reported sales increases of around 19 percent in the last year alone, a year in which the price of produce spiked.

Summarize Argument: Phenomenon-Hypothesis
The newspaper’s conclusion is a hypothesis about the effect of increased produce prices: they’ve resulted in an increase in gardening. To support this hypothesis, the newspaper points to a correlation: during the same year that produce prices rose, sales for two major seed companies also rose.

Notable Assumptions
Based on a mere correlation between produce prices and seed sales, the author concludes that produce prices are responsible for the increase in gardening. So, she assumes there’s not some other explanation for the increased sales. She also assumes that the relationship isn’t reversed—that is, increased seed sales aren’t somehow responsible for rising produce costs. Finally, she assumes a link between seed sales and gardening—namely, that increased sales at just the two largest seed companies is a reliable sign that people are actually gardening more.

A
Increases in produce prices are largely driven by increases in the fuel costs of bringing crops to market.
The cause of increased produce prices provides no info on whether those increased prices have, or have not, had an effect on gardening.
B
The average personal garden is much smaller than it was decades ago when inexpensive produce started to become available.
This suggests that perhaps gardening has declined compared to decades ago, but the argument is focused on whether, and why, gardening activity has changed since only last year.
C
Community gardens report that waiting lists for renting garden plots have gotten longer over the last year.
This suggests that interest in gardening has increased, but offers no insight into whether the actual planting of such gardens has increased or whether produce prices are, or are not, the underlying cause.
D
Personal gardens are usually popular in economic downturns.
Without knowing whether there has been an economic downturn, we can’t assess the effect (D) has on the argument Also, even if there has been a downturn, (D) still allows for increased produce prices to be the cause of the rising popularity of gardens.
E
A large retail seed company went out of business early last year.
This provides an alternative hypothesis for the increased seed sales at the two largest seed companies: one of their competitors went out of business. This undermines the author’s assumption that the increased seed sales were due to rising produce prices.

58 comments

Medical researcher: At the Flegco Corporation, all employees whose work involves lifting heavy objects wear back belts to prevent back injuries. However, a study found that Flegco employees who wear back belts are actually more likely to suffer back injuries than are employees who do not wear back belts. This suggests that back belts do not help to prevent back injuries.

Summarize Argument
The author concludes that back belts don’t help prevent back injuries. This is based on the fact that in a study of Flegco employees, those who wear back belts are more likely to suffer back injuries than employees who don’t wear back belts.

Identify and Describe Flaw
The author overlooks the possibility that the people who wear back belts at Flegco start off with a higher risk of back injuries than the people who don’t wear back belts. For example, maybe the people who wear back belts are involved in manual labor, whereas the people who don’t wear back belts are office workers who don’t lift anything heavy. If this is true, then we can’t conclude that back belts don’t reduce injuries simply because the people who wear back belts have more back injuries than the people who don’t wear the belts.

A
It compares the incidence of back injury between two groups who probably do not have the same risk factors for back injury.
This points out that the people who wear back belts might be more at risk of back injury due to the nature of their job than are the people who don’t wear back belts. This is why the fact that the belt-wearers are more likely to get back injuries does not prove the belts don’t help reduce injuries.
B
It fails to address the possibility that Flegco Corporation employees are more likely to wear back belts than are employees who perform similar tasks in other corporations.
The argument concerns a comparison between Flegco employees. How Flegco employees compare to employees of other corporations is not relevant.
C
It takes for granted that if a factor is associated with an increased likelihood of a certain effect, that factor must causally contribute to that effect.
The author does not assume that back belts causally contribute to back injuries. The conclusion is just that back belts do not help prevent back injuries. In other words, the author could believe back belts simply have no causal relationship to back injuries.
D
It confuses the claim that a phenomenon does not causally contribute to a certain effect with the claim that that phenomenon causally contributes to preventing that effect.
The author concludes that back belts do not help prevent back injuries. This claim is not confused for a claim that back belts do help prevent back injuries.
E
It fails to address the possibility that even if a factor is sufficient to produce a certain effect, its presence may not be necessary in order for that effect to be produced.
(E) describes a confusion of sufficient and necessary conditions. But there is no factor presented as sufficient to guarantee a certain effect. So there can’t be a confusion of sufficient and necessary conditions.

6 comments

The prevailing view among historians is that medieval European peasants were deeply dedicated to religion. But the record keepers in medieval Europe were members of the clergy. It should not surprise us that chroniclers who were professionally occupied with religion would exaggerate people’s religious devotion. Thus, there is reason to doubt the prevailing view of medieval peasants’ piety.

Summarize Argument
The author concludes that that there’s reason to think that medieval peasants were not deeply dedicated to religion. This is because the recordkeepers who recorded the religious devotion of peasants were members of the clergy, who we would expect to exaggerate peasants’ level of religious dedication.

Notable Assumptions
The author assumes that the recordkeepers actually exaggerated peasants’ level of religious dedication. (This overlooks the possibility that, even though we might expect them to have a motive to exaggerate dedication, they did not in fact exaggerate in their records.)

A
Among the written records produced by clergy in medieval Europe and currently available to historians are a number of documents detailing nonreligious, as well as religious, activities of peasants.
The author never assumed that clergy only recorded religious activities of peasants. The assumption is that the level of religious dedication was exaggerated; but this allows for plenty of records related to nonreligious things.
B
Many members of the clergy in medieval Europe spent more time among peasants than among people of any other social class.
This has no clear impact. We don’t know how the amount of time spent among peasants relates to the possibility that clergy exaggerated the level of peasants’ religious dedication.
C
Written records produced by clergy in medieval Europe very rarely portray merchants or nobles as being dedicated to religion.
This undermines the assumption that the clergy exaggerated peasants’ religious dedication. We would expect clergy to exaggerate other peoples’ dedication, too. But if they didn’t exaggerate for merchants/nobles, that suggests they might not have exaggerated for peasants, too.
D
Historians cannot develop a reliable account of the religious attitudes held during any given historical period unless they have consulted all of the relevant surviving records from that period.
This has no clear impact. We don’t know whether historians have consulted all relevant surviving records. Also, even if historians can’t develop a reliable account, that’s consistent with the author’s position that we have reason to doubt the prevailing view.
E
Documents produced by clergy in medieval Europe contain detailed descriptions of participation by peasants and others in religious activities.
The author already recognizes this possibility. His position is that these descriptions are likely to be exaggerations.

27 comments