Until recently, biologists were unable to explain the fact that pathog

Question

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
  (5)   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 do not harm their hosts have the best
chance for long-term survival: they thrive because
  (10)   their hosts thrive. Some biologists, however, recently
have suggested that if a pathogen reproduced so
extensively as to cause its host to become gravely
sick, it could still achieve evolutionary success if its
replication led to a level of transmission into new
  (15)   hosts that exceeded the loss of pathogens 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
  (20)   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
  (25)   reproduces so extensively in a solitary host that the
host is too unwell to leave home for a day, the
thousands of new rhinoviruses produced that day will
die before they can be transmitted. So, because it is
transmitted directly, the common cold is unlikely to
  (30)   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
  (35)   reproduces so extensively that its human host is
immobilized, it can still pass along its genes if a
mosquito bites the host and transmits this dose to the
next human it bites. In such circumstances the
virulence is likely to be more severe, because the
  (40)   pathogen has reproduced to such concentration in the
host that the mosquito obtains a high dose of the
pathogen, increasing the level of transmission to new
hosts.

While medical literature generally supports the
  (45)   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
  (50)   diphtheria and tuberculosis bacteria can be just as
lethal. Scientists call these “sit and wait” pathogens,
because they are able to remain alive outside their
hosts until a new host comes along, without relying
on a vector. Indeed, the endurance of these pathogens,
  (55)   many of which can survive externally for weeks or
months before transmission into a new
host—compared, for instance, to an average
rhinovirus life span of hours—makes them among the
most dangerous of all pathogens.    1 
 1. Which one of the following most accurately summarizes the main idea of the passage?

(A) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that directly transmitted pathogens are just as virulent as vector-borne pathogens, due to the former’s ability to survive outside a host for long periods of time.
(B) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that, while most pathogens reproduce so extensively as to cause their hosts to become gravely sick or even to die, some eventually develop a benign coexistence with their hosts.
(C) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that they are able to achieve reproductive success because they reproduce to a high level of concentration in their incapacitated hosts.
(D) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that they are generally able to achieve reproductive success unless their reproduction causes the death of the host.
(E) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that pathogen virulence is generally a function of their mode of transmission, with vector-borne pathogens usually more virulent than directly transmitted pathogens, except for those directly transmitted pathogens able to endure outside their hosts.

2 
 2. According to the passage, the prevailing view of the host-parasite relationship is that, in general,

(A) the host is ultimately harmed enough to prevent the parasite from thriving
(B) a thriving parasite will eventually incapacitate its host
(C) a parasite must eventually be transmitted to a new host in order to survive
(D) the parasite eventually thrives with no harm to its host
(E) ultimately the host thrives only if the parasite thrives

3 
 3. With which one of the following statements about the prevailing view of host-parasite relations would the biologists mentioned in line 10 be most likely to agree?

(A) The view contradicts most evidence of actual host-parasite relations.
(B) The view suggests that even death-causing pathogens can achieve evolutionary success.
(C) The view presumes the existence of a type of parasite behavior that does not exist.
(D) The view ignores the possibility that there is more than one way to achieve evolutionary success.
(E) The view erroneously assumes that hosts never harm the parasites that feed off them.

4 
 4. The examples of diphtheria and tuberculosis bacteria provide the most support for which one of the following conclusions about the dangerousness of pathogens?

(A) The most dangerous pathogens are those with the shortest life spans outside a host.
(B) Those pathogens with the greatest endurance outside a host are among the most dangerous.
(C) Those pathogens transported by vectors are always the most dangerous.
(D) The least dangerous pathogens are among those with the longest life spans outside a host.
(E) Those pathogens transmitted directly are always the least dangerous.

5 
 5. Which one of the following, if true, would most seriously challenge the position of the biologists mentioned in line 10?

(A) Most pathogens capable of causing their hosts’ deaths are able to achieve reproductive success.
(B) Most pathogens transmitted from incapacitated hosts into new hosts are unable to overwhelm the new hosts.
(C) Most pathogens that do not incapacitate their hosts are unable to achieve reproductive success.
(D) Most hosts that become gravely sick are infected by pathogens that reproduce to relatively high concentrations.
(E) Most pathogens transmitted from incapacitated hosts are unable to reproduce in their new hosts.

6 
 6. Which one of the following most accurately describes the organization of the passage?

(A) introduction of a scientific anomaly; presentation of an explanation for the anomaly; mention of an implication of the explanation; discussion of two examples illustrating the implication; discussion of exceptions to the implication
(B) introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; discussion of exceptions to the explanation; mention of an implication of the explanation
(C) introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; mention of an implication of the explanation; discussion of examples illustrating the implication
(D) introduction of a scientific anomaly; presentation of an implication of the anomaly; discussion of two examples illustrating the implication; discussion of exceptions to the implication
(E) introduction of a scientific anomaly; discussion of two examples illustrating the anomaly; presentation of an explanation for the anomaly; discussion of examples illustrating the explanation

7 
 7. The passage implies that which one of the following is a reason that rhinoviruses are unlikely to be especially virulent?

(A) They immobilize their hosts before they have a chance to reproduce extensively enough to pass directly to new hosts.
(B) They cannot survive outside their hosts long enough to be transmitted from incapacitated hosts to new hosts.
(C) They cannot reproduce in numbers sufficient to allow vectors to obtain high enough doses to pass to new hosts.
(D) They cannot survive long enough in an incapacitated host to be picked up by vectors.
(E) They produce thousands of new rhinoviruses each day.

8 
 8. The primary purpose of the passage is to

(A) compare examples challenging the prevailing view of host-parasite relations with examples supporting it
(B) argue that the prevailing view of host-parasite relations is correct but is based on a mistaken rationale
(C) offer a modification to the prevailing view of host-parasite relations
(D) attack evidence that supports the prevailing view of host-parasite relations
(E) examine the origins of the prevailing view of host-parasite relations

Source:   LSAT Official PrepTest 47   
 Difficulty Level:   650

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 321 Date: 26-Aug-2021
 This question is a part of RC Butler 2021 .  Click here for Details

Makhabbat · Answer

Hello! Please help with explanation: 6,7,8 questions. 
Thank you in advance!

Sajjad1994 · Answer

Passage summary and Map

We hope you weren’t intimidated by the difficult language in this Natural Sciences passage. As always, the test helps those who don’t immediately understand certain vocabulary words by defining them as soon as they appear in the passage (or by providing helpful context). Test takers who aren’t scared off by science get a huge payoff here: eight questions, three of which are Globals and none of which are particularly difficult.

This passage also follows a very common structure.  ”Until recently” (line 1)  scientists held a certain view that it was  “unable to explain”  certain things. Naturally, we expect that the old view with all of its flaws will be contrasted with a new and improved idea: the  “however” in line 10  sets up this dichotomy. Our Topic appears early, and is the same as the biologists’: host–parasite relations. We have to wait until  line 10  to really define the Scope of this passage as why some parasites overwhelm their hosts. The paragraph ends by strongly suggesting the author’s Purpose as exploring or explaining the  “evolutionary success”  of the pathogens that kill their hosts. And that of course is just what the passage ends up doing.

Paragraph 2  begins to flesh out the new hypothesis by discussing one of its implications, namely that how a pathogen is transmitted reflects how nasty that bug is. We expect some evidence for this point of view, and sure enough,  line 22  begins the first of three examples of how it works. The common cold is relatively benign, since it depends upon its host to transmit it; if that host can’t get up and walk around to sneeze on other people, the virus dies off.

Paragraph 3  uses another type of pathogen to carry this implication even further. Viruses that don’t depend on their hosts for transmission (like mosquito-borne ones) can get even nastier than viruses that do. In the final paragraph, we learn that  “medical literature generally supports the hypothesis” (44–45) , with one important exception—the group known as the  “sit and wait pathogens” (line 51) . Those can hang around all by their lonesome selves until a new host comes along. Note that the author never expresses an opinion about this hypothesis beyond saying that the evidence supports it, so this neutrality is the closest we get to a  Main Idea.

Roadmap:

Paragraph 1 —How can pathogens kill hosts? New view

Paragraph 2 —Direct transmission (colds)—mild

Paragraph 3 —Vector transmission (mosquitoes)—severe

Paragraph 4 — “Sit & wait” —worst of all

Sajjad1994 · Answer

Explanation

6. Which one of the following most accurately describes the organization of the passage?

Difficulty Level:   Hard

Explanation

The simplest way to tackle this type of question is to compare the answer choices piece by piece to our Roadmap. Any choice that goes out of order, or that includes something outside the scope of the passage, is incorrect. All of the choices begin with,  “introduction of a scientific anomaly,”  so we’ll have to start eliminating choices based on the second and third phrases of the answer choices. At the end of this process,  (A)  will be the only one that remains:

(B)  lasts through the first round of elimination, but skips from  “presentation of an explanation for the anomaly”  to  “discussion of two examples.”  The correct step for the beginning of  paragraph 2  is  “mention of an implication of the explanation,”  which doesn’t appear in this choice until the very end. Eliminate.

(C)  likewise is fine until we reach the third clause, but reverses the order of  “discussion of two examples”  and  “mention of an implication.”  Eliminate.

(D)  and  (E)  both skip the end of paragraph 1: the  “presentation of an explanation of the anomaly”  that is present in the first three choices. Eliminate.

Answer: A

Sajjad1994 · Answer

Explanation

7. The passage implies that which one of the following is a reason that rhinoviruses are unlikely to be especially virulent?

Difficulty Level:   Easy

Explanation

Rhinoviruses are the first example discussed in the passage, back in  paragraph 2 . Good for you if you skimmed this example the first time around; if this question weren’t on the test, an in-depth reading of this detail would have been a waste of time. Now we can dig deeper, confident that it will earn us a point. We learn from our research that a rhinovirus  “requires physical proximity for transmission” (23–24) , which means that it is  “unlikely to disable its victims” (29–30) . Let’s use those facts to evaluate the choices:

(A)  is exactly what paragraph 2 tells us a rhinovirus doesn’t want to do, immobilize its host so quickly that it doesn’t have a chance to infect a new host. Eliminate.

(B) , on the other hand, sounds pretty good. If rhinoviruses require physical proximity to latch on to a new host, then incapacitating their current host isn’t a good idea.  (B)  even matches up with  lines 57–58 , the only mention of rhinoviruses in the passage outside of  paragraph 2 , which refer to  “an average rhinovirus life span of hours.”  This choice is correct.

(C)  and  (D)  both mention vectors, which are found in  paragraph 3  and have nothing to do with rhinoviruses. Eliminate them both.

(E)  is suggested by  line 27 , but is not given as a reason why rhinoviruses aren’t particularly virulent. Eliminate.

Answer: B

Sajjad1994 · Answer

Explanation

8. The primary purpose of the passage is to

Difficulty Level:   650-700

Explanation

Once again, the author’s neutral point of view helps us eliminate answers quickly on Global questions. We originally predicted that the author’s Purpose was to explain or evaluate the new hypothesis, but since she didn’t offer an opinion on it, perhaps  “describe”  or something similarly neutral will be a better prephrase.

(A)’s “compare examples”  focuses too much on the details of the passage. Even if you were tempted to read further, there are no examples  “supporting”  the prevailing view. Eliminate.

(B)  and  (D)  offer  “argue”  and  “attack,”  respectively. Too harsh. Eliminate.

(C) “Offer”  is sufficiently neutral, even if it wasn’t exactly what we originally predicted. And the  “modification to the prevailing view”  is clearly the new hypothesis that is the focus of the passage. This choice is correct. For the record:

(E)’s “examine”  might be a good start, but  “the origins of the prevailing view”  really aren’t discussed in the passage, and they certainly aren’t its focus.

Answer: C

tkorzhan1995 · Answer

Sajjad1994 , can you please help with q5?

As per the passage, this is the view by biologists:

it could still achieve evolutionary success if its
replication led to a level of transmission into new
(15) hosts that exceeded the loss of pathogens resulting
from the host’s incapacitation.

How E is relevant? How we can imply about reproduction in the new host from statement above. (I have hard time to tie the loss of pathogens resulting from host's incapacitation, level of transmission into new host and transmission from incapacitated host into new host. To sum up, I don't see transmission from incapacitated host to new host in the statement above).

Summary: transmission into new hosts>loss of pathogens from the incapacitated host--> evolutionary success.

Sajjad1994 · Answer

Explanation

5. Which one of the following, if true, would most seriously challenge the position of the biologists mentioned in line 10?

Difficulty Level:   650

Explanation

As always, to weaken an argument we’ll find the evidence and conclusion, formulate the assumption, then try to find evidence that makes it less likely. The biologists in  line 10  conclude that there’s a way for an incapacitating pathogen to  “achieve evolutionary success” (line 13) , namely  “if its replication led to a level of transmission into new hosts that exceeded the loss of pathogens resulting from the host’s incapacitation (13–15).”  In short, even nasty bugs can do well as long as they can get to new hosts in spite of their nastiness. This view assumes that getting to a new host is enough to  “achieve evolutionary success.”  We’ll have to look for a new piece of evidence that tells us otherwise.

(A)  is a 180. If even pathogens that cause death usually achieve reproductive success, the biologists’ argument would be strengthened, not weakened. Eliminate.

(B)  may have been tempting, but a pathogen could still be successful if it can’t overwhelm its new host. In fact, the prevailing view suggests that these newly underwhelming pathogens would even be more successful, since their hosts would be able to transmit them more widely. Eliminate.

(C)  misses the point. The biologists in  line 10  are concerned with pathogens that do incapacitate their hosts, not those that don’t. Eliminate.

(D)  repeats information from  lines 11–13.  This choice merely tells us how pathogens make their hosts gravely ill, not how those same pathogens might (or might not) be successful in spite of causing illness. Eliminate.

(E)  At last, something that weakens the biologists’ position. If the pathogens transmitted from incapacitated hosts can no longer reproduce, they will die off. That certainly doesn’t fit the definition of evolutionary success suggested by  line 9: “long-term survival.”  This choice is correct.

Answer: E

siddhantvarma · Answer

Summary:

The passage discusses a new hypothesis explaining how some pathogens that incapacitate or kill their hosts still achieve evolutionary success. This challenges the prevailing view that host-parasite relationships evolve toward benign coexistence, as parasites would thrive if their hosts survive. The new hypothesis suggests that pathogens' virulence depends on their mode of transmission. Directly transmitted pathogens are usually less virulent, while vector-borne pathogens can be more virulent. However, some directly transmitted pathogens, like diphtheria and tuberculosis, which can survive outside the host for long periods, are exceptions.

Passage Breakdown:  
 
  Paragraph 1 (Lines 1–18):  Introduces a scientific puzzle: pathogens incapacitating their hosts contradict the traditional view that parasites evolve to coexist benignly with their hosts. The new hypothesis suggests pathogens can achieve reproductive success even if they kill their host, as long as they transmit to new hosts. 
  Paragraph 2 (Lines 19–30):  Discusses how virulence depends on the pathogen’s mode of transmission. Rhinoviruses, which require close contact, tend to be less virulent because incapacitating the host reduces their transmission opportunities. 
  Paragraph 3 (Lines 31–44):  Describes how vector-borne pathogens (e.g., malaria) are often more virulent because transmission does not rely on the host’s mobility but on a vector (e.g., a mosquito), which increases transmission even from an incapacitated host. 
  Paragraph 4 (Lines 45–58):  Introduces exceptions: directly transmitted pathogens like diphtheria and tuberculosis can also be highly virulent. These pathogens, called "sit and wait" pathogens, can survive outside their hosts for extended periods, making them dangerous even without vectors.

1. Which one of the following most accurately summarizes the main idea of the passage?

(A) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that directly transmitted pathogens are just as virulent as vector-borne pathogens, due to the former’s ability to survive outside a host for long periods of time.
  This is incorrect   because the passage distinguishes directly transmitted pathogens like rhinoviruses from the more virulent vector-borne pathogens, though it acknowledges exceptions like diphtheria and tuberculosis.

(B) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that, while most pathogens reproduce so extensively as to cause their hosts to become gravely sick or even to die, some eventually develop a benign coexistence with their hosts.
  This is incorrect   because the passage does not suggest that most pathogens eventually develop benign coexistence. The new hypothesis instead explains how pathogens can be successful even when they harm or kill their hosts.

(C) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that they are able to achieve reproductive success because they reproduce to a high level of concentration in their incapacitated hosts.
  This is incorrect   because the passage focuses on the relationship between virulence and mode of transmission, rather than merely on pathogens reproducing in incapacitated hosts.

(D) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that they are generally able to achieve reproductive success unless their reproduction causes the death of the host
  This is incorrect   because the passage does not focus on the reproductive success of pathogens that don’t cause death but on the idea that different transmission modes affect virulence.

(E) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that pathogen virulence is generally a function of their mode of transmission, with vector-borne pathogens usually more virulent than directly transmitted pathogens, except for those directly transmitted pathogens able to endure outside their hosts.
  This is correct   because it accurately reflects the passage's main idea: the new hypothesis links virulence to the mode of transmission, with vector-borne pathogens generally being more virulent but some directly transmitted pathogens posing exceptions due to their endurance outside hosts.

Answer: (E)

2. According to the passage, the prevailing view of the host-parasite relationship is that, in general,

(A) the host is ultimately harmed enough to prevent the parasite from thriving
  This is incorrect   because the prevailing view suggests that parasites and hosts develop benign coexistence, not that the host is harmed enough to prevent the parasite from thriving.

(B) a thriving parasite will eventually incapacitate its host
  This is incorrect   because the prevailing view does not expect thriving parasites to incapacitate their hosts; it assumes benign coexistence.

(C) a parasite must eventually be transmitted to a new host in order to survive
  This is incorrect   because while transmission to a new host is crucial, the prevailing view emphasizes that parasites that do not harm their hosts are more likely to thrive.

(D) the parasite eventually thrives with no harm to its host
  This is correct   because the passage states the prevailing view is that host and parasite develop a benign coexistence, allowing the parasite to thrive without harming the host (lines 5–9).

(E) ultimately the host thrives only if the parasite thrives
  This is incorrect   because the prevailing view prioritizes the parasite thriving without harming the host.

Answer: (D)

3. With which one of the following statements about the prevailing view of host-parasite relations would the biologists mentioned in line 10 be most likely to agree?

(A) The view contradicts most evidence of actual host-parasite relations.
  This is incorrect   because the biologists are not asserting that the prevailing view contradicts most evidence, only that it may not fully account for all pathogen behaviors.

(B) The view suggests that even death-causing pathogens can achieve evolutionary success.
  This is incorrect   because the prevailing view does not suggest that death-causing pathogens achieve evolutionary success. That idea comes from the new hypothesis.

(C) The view presumes the existence of a type of parasite behavior that does not exist.
  This is incorrect   because the prevailing view does not assume a type of parasite behavior that does not exist.

(D) The view ignores the possibility that there is more than one way to achieve evolutionary success.
  This is correct   because the biologists argue that the prevailing view overlooks the fact that there are multiple ways for pathogens to achieve evolutionary success, including through incapacitating their hosts (lines 10–18).

(E) The view erroneously assumes that hosts never harm the parasites that feed off them.
  This is incorrect   because the prevailing view does not assume that hosts never harm parasites.  Answer: (D)

4. The examples of diphtheria and tuberculosis bacteria provide the most support for which one of the following conclusions about the dangerousness of pathogens?

(A) The most dangerous pathogens are those with the shortest life spans outside a host.
  This is incorrect   because pathogens with short life spans (like rhinoviruses) are not considered the most dangerous.

(B) Those pathogens with the greatest endurance outside a host are among the most dangerous.
  This is correct   because the passage emphasizes that "sit and wait" pathogens, which can survive outside hosts for long periods, are particularly dangerous (lines 50–58).

(C) Those pathogens transported by vectors are always the most dangerous.
  This is incorrect   because the passage discusses that some directly transmitted pathogens can also be dangerous, challenging the idea that only vector-borne pathogens are dangerous.

(D) The least dangerous pathogens are among those with the longest life spans outside a host.
  This is incorrect   because the passage suggests that pathogens with long life spans outside hosts can be dangerous.

(E) Those pathogens transmitted directly are always the least dangerous.
  This is incorrect   because directly transmitted pathogens can still be highly dangerous (e.g., diphtheria and tuberculosis).  Answer: (B)

5. Which one of the following, if true, would most seriously challenge the position of the biologists mentioned in line 10?

(A) Most pathogens capable of causing their hosts’ deaths are able to achieve reproductive success.
  This is incorrect   because it supports the biologists' view that even pathogens causing death can achieve reproductive success.

(B) Most pathogens transmitted from incapacitated hosts into new hosts are unable to overwhelm the new hosts.
  This is incorrect   because it does not directly challenge the idea that incapacitating hosts can still lead to reproductive success.

(C) Most pathogens that do not incapacitate their hosts are unable to achieve reproductive success.
  This is incorrect   because it aligns with the biologists' argument that pathogens often incapacitate their hosts and still achieve success.

(D) Most hosts that become gravely sick are infected by pathogens that reproduce to relatively high concentrations.
  This is incorrect   because it does not address the core hypothesis about evolutionary success despite host sickness.

(E) Most pathogens transmitted from incapacitated hosts are unable to reproduce in their new hosts.
  This is correct   because it challenges the biologists' view by suggesting that pathogens from incapacitated hosts may not reproduce in new hosts, undermining the argument that pathogens benefit from incapacitating their hosts (lines 10–15).

Answer: (E)

6. Which one of the following most accurately describes the organization of the passage?

(A) introduction of a scientific anomaly; presentation of an explanation for the anomaly; mention of an implication of the explanation; discussion of two examples illustrating the implication; discussion of exceptions to the implication
  This is correct.   The passage begins by introducing the anomaly, presents a hypothesis, then discusses the implication (mode of transmission and virulence), provides two examples (rhinoviruses and vector-borne diseases), and mentions exceptions (sit and wait pathogens).

(B) introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; discussion of exceptions to the explanation; mention of an implication of the explanation
  This is incorrect   because the exceptions are discussed before the final implication.

(C) introduction of a scientific anomaly; presentation of an explanation for the anomaly; discussion of two examples illustrating the explanation; mention of an implication of the explanation; discussion of examples illustrating the implication
  This is incorrect   because the examples illustrate the explanation, not the implication.

(D) introduction of a scientific anomaly; presentation of an implication of the anomaly; discussion of two examples illustrating the implication; discussion of exceptions to the implication
  This is incorrect   because the anomaly's implication is not presented immediately after the anomaly itself.

(E) introduction of a scientific anomaly; discussion of two examples illustrating the anomaly; presentation of an explanation for the anomaly; discussion of examples illustrating the explanation
  This is incorrect   because the passage first explains the anomaly and then provides examples.  Answer: (A)

7. The passage implies that which one of the following is a reason that rhinoviruses are unlikely to be especially virulent?

(A) They immobilize their hosts before they have a chance to reproduce extensively enough to pass directly to new hosts.
  This is incorrect   because rhinoviruses do not immobilize their hosts quickly.

(B) They cannot survive outside their hosts long enough to be transmitted from incapacitated hosts to new hosts.
  This is correct.   The passage explains that rhinoviruses cannot survive long outside their hosts, so incapacitating their hosts would reduce transmission opportunities (lines 19–30).

(C) They cannot reproduce in numbers sufficient to allow vectors to obtain high enough doses to pass to new hosts.
  This is incorrect   because vectors are not involved in rhinovirus transmission.

(D) They cannot survive long enough in an incapacitated host to be picked up by vectors.
  This is incorrect   because vectors do not pick up rhinoviruses.

(E) They produce thousands of new rhinoviruses each day.
  This is incorrect.   While rhinoviruses reproduce in large numbers, this is not the reason for their low virulence.  Answer: (B)

8. The primary purpose of the passage is to

(A) compare examples challenging the prevailing view of host-parasite relations with examples supporting it
  This is incorrect   because the passage does not focus on comparing examples supporting and challenging the prevailing view.

(B) argue that the prevailing view of host-parasite relations is correct but is based on a mistaken rationale
  This is incorrect   because the passage does not argue that the prevailing view is correct.

(C) offer a modification to the prevailing view of host-parasite relations
  This is correct  . The passage offers a modification to the prevailing view by introducing the new hypothesis regarding virulence and transmission modes.

(D) attack evidence that supports the prevailing view of host-parasite relations
  This is incorrect   because the passage does not attack the prevailing view’s evidence, but rather modifies its rationale.

(E) examine the origins of the prevailing view of host-parasite relations
  This is incorrect   because the passage does not focus on the origins of the prevailing view.  Answer: (C)

Until recently, biologists were unable to explain the fact that pathog

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Until recently, biologists were unable to explain the fact that pathog

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