#24 - Passage Organization

[Administrator]

Complete Question Explanation
(See the complete passage discussion here: lsat/viewtopic.php?t=11562)

The correct answer choice is (A)

The organization of the passage is discussed in the VIEWSTAMP analysis above, and is nicely expanded upon by correct answer choice (A): The question about pathogens is presented, the perspective of “some biologists” is offered in response, implying that the more indirect the transmission the more virulent the pathogen in general. Finally, two exceptions to this general rule (diphtheria and tuberculosis) are presented.

Answer choices (B), (C), (D), and (E) are all wrong because they all include the component, the two examples of diphtheria and tuberculosis are not presented in order to illustrate the biologists’ explanation or implications thereof. They are presented to exemplify exceptions to the rule which links greater virulence to indirectly transmitted pathogens in general.

[Mariam]

Hello- I feel very lost with this question. I am lost in the terminology of the answer choice. can someone please breakdown the differences between the answer choices- especially A and B- they sound very similar. Thanks so much in advance!!

[Christen Hammock]

Hi Miriam!

Happy to help. Instead of getting overwhelmed by the similarity between the two answer choices, think about what's definitely different:

Introduction of a scientific anomaly - nope, same here!;
presentation of an explanation for the anomaly - the same!;

mention of an implication of the explanation (A) versus discussion of two examples illustrating the explanation (B);

discussion of two examples illustrating the implication (A) versus discussion of exceptions to the explanation (B);

discussion of exceptions to the implication (A) versus mention of an implication of the explanation (B)

The third clause ("mention of an implication of the explanation" in Answer Choice (A) makes all the difference! After the author introduces the scientific anomaly and its explanation, Paragraph 2 (lines 19-20) starts with this line: "One implication of this perspective is that . . . ." This happens before the author dives into the two examples illustrating this implication (direct versus vector transmission).

[crispycrispr]

Hi--I originally chose (D), so I was wondering if it's wrong because it misses a whole chunk in the first paragraph, the explanation of the anomaly, and it's not the implication of anomaly, but the implication of the explanation to the anomaly. Thanks!

[AspenHerman]

Hi All!

This might be silly and obvious, but I'm having a hard time making the synapses fly on this question.

How are the final two examples in the last paragraph (diphtheria and tuberculosis) an exception to the implication? If anything, those two are able to achieve transmission/evolutionary success despite incapacitating their hosts, they just transmit a different way.

Additionally, the two examples illustrating the implication, was that the rhinoviruses and mosquito?

This passaged confused me, because how I read it was that: "Here is this old way of thinking about host-parasite relationships, and now here is this new way of thinking of it" and then providing a bunch of examples on how it applies. I didn't see anything that indicated that exceptions were being made here.

Can I have some advice on how to better interpret this passage and others going forward?

[Robert Carroll]

Aspen,

The first sentence of the second paragraph mentions what the implication is - that virulence is a function of mode of transmission. The implication is not the last sentence of the first paragraph, which talks about how death-causing pathogens can still achieve evolutionary success.

Tuberculosis and diphtheria are directly transmitted, which the second paragraph suggests should make them low in virulence, but they're not - so they are exceptions to the implication about mode of transmission determining virulence.

The 30,000-foot view of the passage is basically as follows: The prevailing view of host-parasite relations is that parasites will develop a benign coexistence with their hosts, but that doesn't always happen, so the prevailing view can't be 100% right. Some biologists have proposed that pathogens could be less than benign as long as they can get transmitted to new hosts if they harm their current host. That view implies that we would expect pathogen virulence to be predictable from a given mode of transmission - directly-transmitted will be low in virulence, vector-borne will be high in virulence. That's true for some examples. Rhinoviruses are directly-transmitted and low in virulence, whereas malaria is vector-borne and high in virulence. But exceptions exist that reverse this, with directly-transmitted being high in virulence.

crispy.

The implication is not of the anomaly, but of the new view about pathogens, which is why answer choice (D) is incorrect.

Robert Carroll

[AspenHerman]

Aspen,

The first sentence of the second paragraph mentions what the implication is - that virulence is a function of mode of transmission. The implication is not the last sentence of the first paragraph, which talks about how death-causing pathogens can still achieve evolutionary success.

Tuberculosis and diphtheria are directly transmitted, which the second paragraph suggests should make them low in virulence, but they're not - so they are exceptions to the implication about mode of transmission determining virulence.

The 30,000-foot view of the passage is basically as follows: The prevailing view of host-parasite relations is that parasites will develop a benign coexistence with their hosts, but that doesn't always happen, so the prevailing view can't be 100% right. Some biologists have proposed that pathogens could be less than benign as long as they can get transmitted to new hosts if they harm their current host. That view implies that we would expect pathogen virulence to be predictable from a given mode of transmission - directly-transmitted will be low in virulence, vector-borne will be high in virulence. That's true for some examples. Rhinoviruses are directly-transmitted and low in virulence, whereas malaria is vector-borne and high in virulence. But exceptions exist that reverse this, with directly-transmitted being high in virulence.

crispy.

The implication is not of the anomaly, but of the new view about pathogens, which is why answer choice (D) is incorrect.

Robert Carroll

Alright, thank you Rob!