Researchers studying how genes control animal behavior have

Question

Researchers studying how genes control animal behavior have had to deal with many uncertainties. In the first place, most behaviors are governed by more than one gene, and until recently geneticists had no method for identifying the multiple genes involved. In addition, even when a single gene is found to control a behavior, researchers in different fields do not necessarily agree that it is a “behavioral gene.” Neuroscientists, whose interest in genetic research is to understand the nervous system (which generates behavior), define the term broadly. But ethologists—specialists in animal behavior—are interested in evolution, so they define the term narrowly. They insist that mutations in a behavioral gene must alter a specific normal behavior and not merely make the organism ill, so that the genetically induced behavioral change will provide variation that natural selection can act upon, possibly leading to the evolution of a new species. For example, in the fruit fly, researchers have identified the gene Shaker, mutations in which cause flies to shake violently under anesthesia. Since shaking is not healthy, ethologists do not consider Shaker a behavioral gene. In contrast, ethologists do consider the gene period (per), which controls the fruit fly’s circadian (24-hour) rhythm, a behavioral gene because flies with mutated per genes are healthy; they simply have different rhythms.   1 
 1. The passage suggests that neuroscientists would most likely consider Shaker to be which of the following?

A. An example of a behavioral gene
B. One of multiple genes that control a single behavior
C. A gene that, when mutated, causes an alteration in a specific normal behavior without making the organism ill
D. A gene of interest to ethologists but of no interest to neuroscientists
E. A poor source of information about the nervous system

2 
 2. It can be inferred from the passage that which of the following, if true, would be most likely to influence ethologists’ opinions about whether a particular gene in a species is a behavioral gene?

A. The gene is found only in that species.
B. The gene is extremely difficult to identify.
C. The only effect of mutations in the gene is to make the organism ill.
D. Neuroscientists consider the gene to be a behavioral gene.
E. Geneticists consider the gene to be a behavioral gene.

3 
 3. The primary purpose of the passage is to

A. summarize findings in an area of research
B. discuss different perspectives on a scientific question
C. outline the major questions in a scientific discipline
D. illustrate the usefulness of investigating a research topic
E. reconcile differences between two definitions of a term

Note:  Verbal OG 2019 question order is #3, #1, #2
RC00322-01
RC00322-02
RC00322-05

GMATNinja · Accepted Answer

Question 1

This might sound obvious, but the most important thing here is to remember what the question asks us to do:
 
This comes up in CR all the time. The task of this question is  not  to identify an ironclad inference. We  do not  have to find a statement that is 100% logically airtight. Instead, the question asks us:

From the author's perspective, which of these choices gets closest to what neuroscientists believe about Shaker?"

We'll get to the right answer choice by eliminating anything that explicitly contradicts the passage and keeping the choice that (according to the passage) is  most likely  what neuroscientists believe.

Hmmm, seems simple enough!

The author brings up neuroscientists and ethologists because they have contrasting definitions of what a "behavioral gene" is. Then the author offers the fruit fly and its Shaker gene  as an example of that contrast . Ethologists  do not consider Shaker to be a behavioral gene . So it's fair to say that the author  suggests  that neuroscientists would consider Shaker to be a behavioral gene.

This isn't 100% airtight, but we don't need airtight. We need something that neuroscientists  would most likely consider  Shaker to be. So let's keep (A) around, and see if anything else gets us closer.

A similar statement appears at the start of the passage:

"In the first place, most behaviors are governed by more than one gene."

So we have a fact regarding  most behaviors . And this is a textbook example of an answer choice that "just sounds right." But the question asks us specifically what  neuroscientists  most likely believe to be true about  Shaker  in particular. We're missing critical information to connect the dots here:

We don't see any information explicitly telling us that the shaking behavior caused by mutations in Shaker is influenced by multiple genes. 
 We don't see any suggestion that neuroscientists think this shaking behavior is included in the group of "most behaviors" that are governed by multiple genes.

This lack of information alone may not be enough to eliminate choice (B). However, it is enough to reject (B) in favor of (A).

All we know is that "researchers have identified  THE  gene Shaker, mutations in which cause flies to shake violently under anesthesia." If anything, this suggests that Shaker is in fact the  only  gene governing the shaking behavior. After all, the mutations that cause violent shaking take place within Shaker -- which has been apparently named after the behavior it causes. The earlier statement about  most  behaviors (not all behaviors) doesn't override the evidence about this particular behavior.

Choice (A) is already a much simpler and better supported choice, so let's stick with (A) and eliminate (B).

According to the passage, there's no denying that mutation in Shaker causes fruit flies to become ill, regardless of whether you're a neuroscientist or an ethologist. Eliminate (C).

There's absolutely nothing in the passage to back this up or even suggest that neuroscientists has "no interest" in Shaker. Eliminate (D).

There's absolutely nothing in the passage to back this up or even suggest that neuroscientists consider Shaker to be "a poor source of information" about the nervous system. Eliminate (E).

I hope this helps Shake off your doubts about the OA! (Ha. I'm hilarious. Or not... :suspect )

GMATPill · Answer

THis is an inference question -- GMATPill Framework #8 Inference

The ETHOLOGISTS' opinion is ....where?

Well, it's not going to be in the beginning -- we have what researchers think in the beginning. But what is crucial to this question is not going to be here. We want to jump to the point in the passage where we talk about the ethologists' opinion and what they really care about.

So there you have it. We got the point where the ethologists INSIST -- this is a strong word. It indicates what they care about. And they care whether mutations make a change beyond just making them "ill".

So in #2, if (C) is true:
The only effect of mutations in the gene is to make the organism ill.

Then ETHOLOGISTS would INSIST that this is not a behavioral gene. It satisfies the question -- which MOST LIKELY INFLUENCES the ethologists' opinion.

GMATPill · Answer

If you read the passage, you'll notice the keyword "But ethologists..."

What was happening before? In the prior sentence, we were talking about NEUROSCIENTISTS. But now, we are talking about ETHOLOGISTS. They have DIFFERENT opinions.

What exactly is the difference? Well, later on, we see that ETHOLOGISTS do not consider Shaker a behavioral gene. Since ethologists and neuroscientists differ in the terms/scope of the word "behavioral gene" -- and ethologists do not consider Shaker a "behavioral gene". Then, well, it's likely that NEUROSCIENTISTS DO consider shaker to be a "behavioral gene".

The key to getting this question correct was to see that the passage compared the perspectives of NEUROSCIENTISTS vs ETHOLOGISTS -- and most of the passage elaborated on the perspective of the ETHOLOGISTS.

GMATPill · Answer

What is this passage talking about? Well, we are not summarizing findings here. This whole passage was talking about how ethologists' opinion differed from neuroscientists. What was considered a behavioral gene actually is NOT -- then an example of what IS towards the end.

This sentence in the first half of the passage:
"even when a single gene is found to control a behavior, researchers in different fields do not necessarily agree that it is a 'behavioral gene.' "

So you can see, these are all "different" perspectives....on what? on what a "behavioral gene" is.

TGC · Answer

I cannot contradict you on this, but I am little convinced.

The only information we have regarding NEUROSCIENTISTS is that they define the term 'Behavioral gene' broadly.
And on the other hand ETHOLOGISTS define the term 'Behavioral gene' narrowly.

Now, shaker is not considered as BG by ETHOLOGISTS, but that doesn't mean that shaker will be considered by NEUROSC as BG.

Broadly is not OPPOSITE of narrowly, it is just the difference in scope.

NEUROSC may or may not consider Shaker as a BG.

Please advise !

rahul241sinha · Answer

I too selected the wrong answer for question #2....but I didn't read the question properly....heres my explanation about the correct answer C ....the important word in the question is 'whether' ....in gmat we use 'whether' wrt either 'yes' or 'no'. The passage clearly states" They insist that mutations in a behavioral gene must alter a specific normal behavior and not merely make the organism ill" .
So think of it as a yes or no question....
Yes - the gene does more than merely making the organism ill i.e.altering specific behaviour. (so its a behavioural gene)
No - the gene does not anything other than make the organism ill. (so its not a behavioural gene) ...Hope this helps

narmfarmer · Answer

I had the same problem with question 1, and it took me a few readings before I could imply that A is corrrect
here's my take on why question 1's OA is A

this excerpt's idea, as mentioned in the first two sentences, is that the study of behavioral genes are uncertain

and this is because 1. behavior genes are hard to identify, and 2. experts in different fields disagree with each other

and then the author supports this by listing the example of Neuroscientists and Ethologists, neuro's views are broad while etho's views are narrow

this is followed by the example of the shaker gene, author's purpose of using the shaker gene example is to point out the uncertainty of study due to these experts' disagreements.

so the answer choice to question 1 must be something in contrast of the Ethologist viewpoint

B doesn't feature enough conflict, also behaviors can also be dictated by a single gene as mentioned sentence 3.
C is too specific of an implication and is not as 'safe' as A
D and E are fillers

A is then a somewhat general answer
and I think it only works because the author's purpose of "Neuro vs Etho" is to point out conflicting perspectives

himanshukamra2711 · Answer

I have a question.

From q1 i inferred within 20 seconds that neuroscientists view is opposite so what ethnologist will consider behavioral gene the same will not be considered by NS(means that Shacker is a behavioral gene),however in second question also if the viewpoint is opposite then why can't we say that if NS believes something to be a behavioral gene the EN will not.

pra1785 · Answer

Discuss perspectives on a scientific question.

What is the scientific question here? I don't get why this is the right answer.

jawele · Answer

I agree. Why is this the correct answer? I picked C. However, I guess the author does not just merely outline the questions ...

GMATNinja · Answer

Let's take a closer at what, exactly, question #2 is asking:

The question isn't asking us to identify which of the choices is true according to the passage. Instead, we must find the choice  that would most likely influence whether ethologists think  a given gene is a behavioral gene.

We can eliminate (D) because nothing in the passage suggests that the opinion of neuroscientists influences the opinion of ethologists.

On the other hand, we are told that ethologists do not consider Shaker to be behavioral because shaking is not healthy. So if an ethologist were told that the only effect of a mutation is to make an organism ill, this new information would definitely have an impact on whether they classified the corresponding gene to be behavioral or not (they would classify it as not behavioral).

That's why (C) is the best answer choice, and (D) can be eliminated. Remember that the GMAT doesn't require you to connect every question for an RC passage to each other. You just need to answer the specific question being asked, then move on.

I hope this helps!

GMATNinja · Answer

The "scientific question" is "How do you researchers define behavioral?"

It's a little tough to spot because the author doesn't come out and say this very explicitly. But when thinking, "Why did the author write this?" I end up in the same place as  GMATPill :

even when a single gene is found to control a behavior, researchers in different fields do not necessarily agree that it is a “behavioral gene.”

The author dives into this topic by writing about the contrasting views of neuroscientists and ethologists. While most of the word count in this passage is spent on how ethologists treat the case of Shaker, the author does this for the sake of illustrating the contrast in perspectives.

(B) is the best choice because it most clearly describes that motivation to present the contrast.

We can eliminate (C) because the author didn't write the passage to  outline major questions . If this were true, we'd see more of an outline-like breakdown of more than one question. Instead, we have a deep dive into a single question ("How do these two groups define behavioral?") and a single example (Shaker) used to address that question.

I hope this helps!

AashishGautam · Answer

Hi GMATNinja

can you explain the error in this line of reasoning with respect to question 1
I choose answer option D, here's my reasoning.

Firstly Given,
Neuroscientists, whose interest in genetic research is to understand the nervous system (which generates behavior),   define the term broadly  . But ethologists—specialists in animal behavior—are interested in evolution,   so they define the term narrowly  .

Now since neurologists define this research broadly, they might not consider this important at all.
Hence, this was the only OA that made sense to me.

Secondly considering your line of reasoning,

I am confused that the difference between Neurologists and ethologists is in defining the terms broadly & narrowly, not altogether a contrast.

Please explain, this seems to be eating my head :-/

Deadpool3 · Answer

Hi  GMATGuruNY  ,  VeritasKarishma ,  ChiranjeevSingh ,  Skywalker18 ,  egmat ,  TheEconomistGMAT ,  GMATNinjaTwo   GMATNinja   generis   hazelnut   mikemcgarry

Could you please clarify the logical gap that I am inferring in the passage.

But ethologists—specialists in animal behavior—are interested in evolution, so they define the term narrowly. They  insist that mutations  in a  behavioral gene  must  alter a specific normal behavior  and  not merely make the organism ill , so that the genetically induced behavioral change will provide variation that natural selection can act upon, possibly leading to the evolution of a new species. For example,  in the fruit fly , researchers have identified  the gene Shaker,   mutations in which cause flies to shake violently  under anesthesia. Since  shaking is not healthy ,  ethologists do not consider Shaker a behavioral gene . In contrast, ethologists do consider the gene period (per), which controls the fruit fly’s circadian (24-hour) rhythm, a behavioral gene because flies with mutated per genes are healthy; they simply have different rhythms.

In the above highlighted text, Since Fruit fly is shaking means a behaviour change, plus shaking is not healthy -->Shouldn't this lead to inferring it as behavioral gene

Since,  Ethologists --> behaviour change + make ill --> behavioral gene

KarishmaB · Answer

... ethologists—specialists in animal behavior—are interested in evolution, so they define the term (behavioral gene) narrowly. They insist that mutations in a behavioral gene must alter a specific normal behavior and not merely make the organism ill, so that the genetically induced behavioral change will provide variation that natural selection can act upon, possibly leading to the evolution of a new species. For example, in the fruit fly, researchers have identified the gene Shaker, mutations in which cause flies to shake violently under anesthesia. Since shaking is not healthy, ethologists do not consider Shaker a behavioral gene. In contrast, ethologists do consider the gene period (per), which controls the fruit fly’s circadian (24-hour) rhythm, a behavioral gene because flies with mutated per genes are healthy; they simply have different rhythms.

As per ethologists, a behavioral gene is that in which mutations alter normal behaviour e.g. period gene which controls the circadian rhythm. A mutation in this changes the fly's rhythm. So now natural selection can possibly lead to the evolution of a new species with a different rhythm. 
As per ethologists, genes in which mutations only make the organism ill are not behavioral genes e.g. shaker gene. Mutations in shaker genes cause the fly to shake violently under anaesthesia (makes the fly ill) but does not change its normal behaviour (the things the fly does when normal and awake). Hence, as per them, gene shaker is not a behavioral gene.

Normally one would think that a mutation in a gene would cause the organism to be ill. That is why the author writes "... mutations in a behavioral gene must alter a specific normal behavior  and not merely make the organism ill ". Whether mutations in behavioral genes actually do make the fly ill too, we can't say. The distinction between non behavioral gene and behavioral gene (as per ethologists) is that a mutation in behavioral gene causes changes in behaviour which natural selection can choose to favour to bring new species.

Neuroscientists, whose interest in genetic research is to understand the nervous system (which generates behavior), define the term broadly. So we can assume that both genes would be called behavioral genes as per neuroscientists.

saby1410  - Hope it answers your question too.

GMATNinja · Answer

The passage does set up a contrast between how neurologists and ethologists define "behavioral genes."

Ethologists are looking for a very particular set of criteria in a behavioral gene. They think that to qualify as a behavior gene, that gene "must alter a specific normal behavior  and not merely make the organism ill , so that the genetically induced behavioral change will provide variation that natural selection can act upon, possibly leading to the evolution of a new species."

This is a  more narrow  definition than the one used by neurologists. Neurologists will call a gene a "behavioral gene" if that gene controls a behavior -- they don't care exactly  what  that behavior is.

Let's say that there is a gene that just makes an animal get violently ill when it goes into the sunlight. A neurologist would call this a behavioral gene, because it controls the behavior of the animal. An ethologist, on the other hand, would NOT call this a behavioral gene. Because this particular gene just makes an animal sick, it does not provide variation that natural selection can act upon.

The gene discussed in question 1 is very similar to the example above. Ethologists would NOT consider it a behavior gene, but neurologists most likely would.

Here's (D):
 
From the above analysis, we know that neurologists would consider Shaker to be a behavioral gene. There's no way we can infer from this that they would  not  be interested in Shaker -- if anything, the passage implies that they WOULD be interested in Shaker because it fits their definition of behavioral gene.

(D) is out and (A) is the correct answer to question 1.

I hope that helps!

Will2020 · Answer

GMATNinja Why can't we use the exactly same explanation you gave above to choose (A) to pick (D) on the second question ? The only thing I can think about is that since the neuroscientists define the term broadly, their definition could encompass the definition of ethologists, so ethologists may agree or disagree about whether a gene being a behavioral one. In that sense, the neuroscientists view about a behavioral gene would influence the ethologists' opinions ONLY sometimes, only in the case when Neuroscientists consider the gene to be a behavioral one and also when their is evidence that the Shaker becomes ill. Does that make sense to you? Thank you!

GMATNinja · Answer

Remember, you need to treat each question on an RC passage individually. Just because the two questions sound similar doesn't necessarily mean you'll use the same technique to solve them.

There's a full explanation of why (D) is not the correct answer to question 2 in  this post .

To answer your question, just because the neuroscientists and ethologists have DIFFERENT definitions doesn't mean that one of those groups INFLUENCES the other. It's totally possible that the ethologists think that neuroscientists are total idiots and that the neuroscientists' definition is just wrong. Nothing in the passage implies that one group influences the other despite their differences of opinion.

I hope that helps!

Will2020 · Answer

DmitryFarber VeritasKarishma mcelroytutoring Regarding question 2, I understand why C is the correct AC, but I can NOT understand why D is wrong? If ethologists and neuroscientists have contrasting definitions regarding behavioral gene, why the neuroscientists opinion can not influence the ethologists opinions about whether a particular gene in a species is a behavioral gene? Didn't we assume that to answer question 1? Many tks!

Researchers studying how genes control animal behavior have

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Researchers studying how genes control animal behavior have

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