Reading ComprehensionDifficulty: Hard

PT120 S2 P4 Q24 Explanation

Pathogens

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TopicsOrganizationScience

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Passage

Until recently, biologists were unable to explain the fact that pathogens—disease-causing parasites—have evolved to incapacitate, and often overwhelm, their hosts. Such behavior is at odds with the prevailing view of host-parasite relations—that, in general, host and parasite ultimately develop a benign coexistence. This view is based on the idea that parasites that resulting from the host’s incapacitation. This scenario suggests that even death-causing pathogens can achieve evolutionary success.

One implication of this perspective is that a pathogen’s virulence—its capacity to overcome a host’s defenses and incapacitate it—is a function of its mode of transmission. For example, rhinoviruses, which cause the common cold, require physical proximity for transmission to occur. If a rhinovirus reproduces so extensively in a solitary host that because it is transmitted directly, the common cold is unlikely to disable its victims.

The opposite can occur when pathogens are transported by a vector—an organism that can carry and transmit an infectious agent. If, for example, a pathogen capable of being transported by a mosquito reproduces so extensively that its human host is immobilized, it can still pass along its genes if a mosquito bites mosquito obtains a high dose of the pathogen, increasing the level of transmission to new hosts.

While medical literature generally supports the hypothesis that vector-borne pathogens tend to be more virulent than directly transmitted pathogens—witness the lethal nature of malaria, yellow fever, typhus, and sleeping sickness, all carried by biting insects—a few directly transmitted pathogens such as diphtheria and tuberculosis bacteria can be just as lethal. Scientists call to an average rhinovirus life span of hours—makes them among the most dangerous of all pathogens.

What this question is testing

Organization

Your task

Pin down exactly what the question asks about the passage — a detail, the author's view, the structure, or the main point — before looking at the choices.

Common trap

Answers that restate a true detail from the passage but don't answer the specific question being asked.

Winning move

Anticipate the answer in your own words from the passage, then find the choice that matches that prediction.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
24.

Which one of the following most accurately describes the organization of

Answer choices

  1. Correct48% picked this

    introduction of a scientific anomaly; presentation of an explanation for the anomaly; mention of an implication of the explanation; discussion of two examples illustrating

    Why this is right

    The last ingredient is "exceptions to the implication", which works. The final paragraph discussed some exceptions to the implication that "vector-borne tend to be more virulent than directly transmitted": a few directly transmitted pathogens such as diptheria and tuberculosis bacteria can be just as lethal (as vector-borne pathogens). So let's read the rest: 1. scientific anomaly - "biologists were unable to explain / such behavior is at odds with prevailing view" (beginning of 1st P) 2. presentation of explanation for anomaly - the reason why pathogens often evolve to overwhelm their hosts is that the pathogen can still achieve evolutionary success if it transmits enough into new hosts. (end of 1st P) 3. mention of an implication - "One implication of this perspective is that virulence is connected to mode of transmission" (beginning of 2nd P) 4. discussion of two examples - For example, rhinoviruses are direct transmit / low virulence (2nd paragraph). A pathogen capable of being transported by a mosquito is vector transmit / high virulence (3rd paragraph) 5. discussion of exceptions to the implication - Last paragraph

    Skill tested: Organization · how this choice captures the passage's function is the move to repeat next time.

  2. Wrong Order10% picked this

    introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; discussion of exceptions to the

    Oddly, this has basically all the same ingredients as (A), just in different order. The last ingredient should go 3rd in this list, since the implication is named at the beginning of paragraph 2. There is no implication mentioned in the last paragraph, just exceptions to the implication.

  3. Bad Last Ingredient9% picked this

    introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; mention of an implication of

    When we check in on this last ingredient, it makes it seem like final paragraph was all about examples of an implication. But the last paragraph begins, While medical literature generally supports [the implication], a few directly transmitted pathogens such as diphtheria and tuberculosis bacteria can be just as lethal. And then the rest of the 3rd paragraph goes on to flesh out these examples of exceptions to the implication.

  4. Bad Match: implication of anomaly30% picked this

    introduction of a scientific anomaly; presentation of an implication of the anomaly; discussion of two examples illustrating the implication; discussion

    This is extremely close to (A), so we are pretty much stuck analyzing the difference between (A) and (D). The 2nd ingredient here is "an implication of the anomaly". The 2nd ingredient in (A) is "explanation for the anomaly". The anomaly was that "even though the prevailing view is that host and parasite develop a benign coexistence, there are some anomalous cases where the parasite evolves to overwhelm and incapacitate their hosts". An implication of the anomaly would be something like, "Given that some parasites actually evolve to overwhelm their hosts, we need to figure out which parasites those are so that we can develop medications to limit the parasites' damage." An explanation for the anomaly would be, "How is it that parasites could evolve to overwhelm their hosts?" The second half of the 1st paragraph explains how this anomaly could occur -- even though the parasite overwhelms the host, the parasite could still achieve evolutionary success if its replication led to a level of transmission that exceeded the loss of pathogens from the host being overwhelmed. The implication that gets mentioned at the outset of the 2nd paragraph isn't an implication of the anomaly. It's an implication of "this perspective". What is "this perspective"? It's the perspective of "some biologists" who have suggested a possible explanation for the anomaly.

  5. Bad Last Ingredient Wrong Order4% picked this

    introduction of a scientific anomaly; discussion of two examples illustrating the anomaly; presentation of an explanation for the anomaly; discussion

    When we check in on this last ingredient, it makes it seem like final paragraph was examples that illustrate an explanation, whereas we thought of the last paragraph as discussing nonconforming examples that don't illustrate the main thrust of the passage. Furthermore, the "explanation for the anomaly" comes at the end of the 1st paragraph, not after the two examples are discussed (P2 and P3).

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