Summary
Viruses can have beneficial effects.
Some viruses kill more-complex organisms. Some of these more-complex organisms that are killed by viruses are deadly to humans.
Viruses have simple structures. Modifying these structures can make a virus deadly to humans.
Random mutations commonly produce changes in the structures of viruses.
Any virus can easily become dangerous to humans.
Some viruses kill more-complex organisms. Some of these more-complex organisms that are killed by viruses are deadly to humans.
Viruses have simple structures. Modifying these structures can make a virus deadly to humans.
Random mutations commonly produce changes in the structures of viruses.
Any virus can easily become dangerous to humans.
Notable Valid Inferences
There’s no clear inference to draw. I’d rely on process of elimination to identify what must be false.
A
Random mutation makes some deadly viruses beneficial to humans.
Could be true. We know mutations can make viruses dangerous. That doesn’t mean mutations can’t make deadly viruses beneficial.
B
Some organisms of greater complexity than viruses are no more likely than viruses to undergo significant alterations through random mutation.
Could be true. It’s possible that there are some viruses that are less likely or equally likely as viruses to undergo major changes from mutations. We were never told that viruses are the least likely to undergo major changes from mutation.
C
Some microorganisms that are more complex than viruses are beneficial to humans.
We know some microorganisms that are more complex than viruses can kill humans. But there could be other microorganisms that are more complex than viruses that are beneficial to humans.
D
Some viruses that fail to kill other viruses that are deadly to humans are nevertheless beneficial to humans.
Could be true. Some viruses could be beneficial in other ways besides killing organisms that are deadly to humans. That was just one example of a benefit.
E
No virus that is deadly to organisms of greater complexity than itself is beneficial to humans.
Must be false. We know some viruses kill more-complex organisms that are deadly to humans. So these viruses are beneficial to humans by killing organisms that might kill humans.
Summary
In the retina, light is registered when photons make contact with molecules of rhodopsin and cause the molecules to change shape. Rhodopsin molecules sometimes change shape caused by normal molecular motion, which causes errors in the visual system. The amount of normal molecular motion is directly proportional to the temperature of the retina.
Strongly Supported Conclusions
The warmer the retina, the higher the chance that errors in the visual system occur.
A
The temperature of an animal’s retina depends on the amount of light the retina is absorbing.
This answer is not supported. We don’t know whether the amount of light the retina absorbs actually causes the retina to change in temperature.
B
The visual systems of animals whose body temperature matches that of their surroundings are more error-prone in hot surroundings than in cold ones.
This answer is strongly supported. If the amount of normal molecular motion that causes visual errors is proportional to the temperature of the retina, then the warmer an animals’ environment the more error-prone that animal’s visual system is.
C
As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons.
This answer is unsupported. We don’t know from the stimulus how quickly rhodopsin reacts after being struck by photons.
D
Rhodopsin molecules are more sensitive to photons in animals whose retinas have large surface areas than in animals whose retinas have small surface areas.
This answer is unsupported. We don’t know from the stimulus if the surface area of an animal’s retina is correlated with the sensitivity of rhodopsin molecules.
E
Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina.
This answer is unsupported. We don’t know whether rhodopsin is the only pigment molecule. We only know that it is an example of a naturally occurring pigment molecule.
Summarize Argument
The critic concludes the “society-as-body” metaphor justifies authoritarian rule better than other metaphors. Why? Because metaphors are popular to the extent they’re politically useful, and the society-as-body metaphor is popular in authoritarian societies.
Notable Assumptions
The critic assumes there’s no political use for the society-as-body metaphor except to justify authoritarian repression. He also assumes the society-as-family metaphor and the other metaphors mentioned are less popular in authoritarian societies than the society-as-body metaphor.
A
In authoritarian societies, the metaphor of society as a family is just as pervasive as the society-as-body metaphor.
This disputes the author’s assumption that the society-as-family metaphor is less popular than the society-as-body metaphor. If both metaphors are equally widespread, then the society-as-body metaphor cannot be popular simply because it justifies authoritarian rule.
B
Every society tries to justify the legitimacy of its government through the use of metaphor.
This strengthens the critic’s argument. It explains why the society-as-body metaphor would be politically useful to authoritarian governments.
C
The metaphor of society as a human body is sometimes used in nonauthoritarian societies.
This doesn’t say the society-as-body metaphor is popular in nonauthoritarian societies. It may be quite rare, in which case its relative popularity in authoritarian societies still supports the argument.
D
Authoritarian leaders are always searching for new metaphors for society in their effort to maintain their power.
This doesn’t say the society-as-body metaphor becomes less useful to authoritarian leaders over time—they can search for new metaphors without abandoning old ones.
E
The metaphor of society as a human body governed by a head is rarely used in liberal democracies.
This strengthens the argument. It supports the critic’s claim that metaphors are popular to the extent they’re politically useful, since it suggests the society-as-body metaphor is much more popular in authoritarian societies than in liberal democracies.