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Source: Official Guide Revised GRE 1st Ed. Part 8; Section 4; #20


Wills argues that certain malarial parasites are

Wills argues that certain malarial parasites are especially (i) because they have more recently entered humans than other species and therefore have had (ii) time to evolve toward (iii). Yet there is no reliable evidence that the most harmful Plasmodium species has been in humans for a shorter time than less harmful species. Blank (i): populous, malignant, threatened Blank (ii): ample, insufficient, adequate Blank (iii): virulence, benignity, variability

3 Explanations


Jacob Elder

If less time results in greater harmfulness of the species as said in the video, then shouldn't the more recently entered parasite therefore have had "ample" or "adequate" time to evolve toward "virulence"? If less or shorter time is how the parasites evolve and become more harmful, shouldn't recent be sufficient, not insufficient?

Jan 22, 2016 • Comment


Hi Jacob,

This one is a bit confusing.

Here's what we know:

1. More time in the body --> less harmful
2. Not enough time in the body --> more harmful

It doesn't make sense to say that the more recently entered parasite has had "ample" or "adequate" time to become more harmful. If it entered more recently, it must have had *less* time than a parasite that entered a longer time ago.

If we accept that less time in the body = more harmful, and more time in the body = less harmful, then the more time it spends in the body, it must be evolving toward *benignity* (a state of not being harmful). That's the logic that is at work here.

Jan 25, 2016 • Reply


Thanks Kevin! Your explanation makes sense. However, if you interpret the question as "the more recently they enter human body, the longer they have lingered and thus evolved outside human body", then both BDG and BFG I think make sense now. In other words, the more recently they infect human, they longer time they have to evolve and become virulent (outside human body).

They problem of this question is that we don't know if the evolution of the virus happen inside or outside human body. The second sentence does not specify, nor does the first. Merely the "more recent" obviously does not imply anything.

Jul 5, 2014 • Comment

Happy to help! I think that you are forgetting to look a the second sentence, though. That is where we learning about the timing. You said we don't know where the parasites evolve, but we do know. We know the evolution takes place in the body, and we know that more time in a person means less harmful. Or as Chris says in the video—less time in the body means more harmful. I recommend re-watching the video if this doesn't make sense. :D

Jul 8, 2014 • Reply


Chris Lele

Oct 10, 2012 • Comment

Rajat Kathuria

Why is B/D/G combination incorrect?

Feb 16, 2014 • Reply

Hi Rajat, thanks for your question! :)

So the reason we can't use that combination is because it doesn't agree with the content of the second sentence. Let's look at the sentence.

For one, we know that there is no evidence of what Willis is claiming. And what is he claiming? We learn this in the second sentence too. Harmful species have been in humans for less time than other species which are not as harmful. This forms the backbone of our understanding of the first sentence.

So it seems you understand part of this if you choose B. Let's turn to the second blank and third blank:

Some species are more dangerous because "they have more recently entered humans than other species and therefore have had (ii)_(less)_time to evolve toward (iii)_(being less harmful)_."

As you can see I filled in the blanks with my own words based on what I know from the second paragraph. Willis thinks that species that entered humans more recently are more dangerous and those that have been around awhile are less dangerous. The idea is that humans can adapt to a species over a long period of time and not be as harmed by the organism.

Looking at (D) ample, this means there has been enough time. And (g) virulence means to be harmful. So this would twist the logic of the second sentence. It now says that having enough time will make the organism harmful, but that is not what the second sentence says. We are told that an organism that has been around for a long time is NOT as harmful as one that has been around for a short time.

Does that make sense? Let me know if I need to clarify anything. :)


Feb 21, 2014 • Reply

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