There is no consensus among researchers regarding what qualifies

Question

There is no consensus among researchers regarding what qualifies a substance as a pheromone. While most agree on a basic definition of pheromones as chemicals released by one individual of a species which, when detected by another individual of the same species, elicit a specific behavioral or physiological response, some researchers also specify that the response to pheromones must be unconscious. In addition, the distinction between pheromones and odorants—chemicals that are consciously detected as odors—can be blurry, and  some researchers  classify pheromones as a type of odorant. Evidence that pheromone responses may not involve conscious odor perception comes from the finding that in many species, pheromones are processed by the vomeronasal (or accessory olfactory) system, which uses a special structure in the nose, the vomeronasal organ (VNO), to receive chemical signals. The neural connections between the VNO and the brain are separate from those of the main olfactory system, whose processing of odorants triggers sensations of smell. But while the VNO does process many animal pheromone signals, not all animal pheromones work through the VNO. Conversely, not all chemical signals transmitted via the VNO qualify as pheromones. For example, garter snakes detect a chemical signal from earthworms—one of their favorite foods—via the VNO, and they use this signal to track their prey.   1 
 1. It can be inferred from the passage that in classifying pheromones as a type of odorant, the researchers referred to the highlighted text posit that

(A) pheromones are perceived consciously
(B) most pheromones are processed by the VNO
(C) most chemical signals processed by the VNO are pheromones
(D) Pheromone perception does not occur exclusively between members of the same species.
(E) pheromones do not always elicit a specific behavioral or physiological response

2 
 2. According to the passage, the fact that pheromones are processed by the VNO in many animal species has been taken as evidence of which of the following?

(A) The accessory and main olfactory systems are not separate
(B) Odorants and pheromones are not distinct types of chemicals.
(C) Odorants and pheromones both elicit a specific behavioral response.
(D) Pheromones do not trigger conscious sensations of smell.
(E) Pheromones aid animals in tracking prey.

3 
 3. The primary purpose of the passage is to

(A) compare and contrast the ways in which the vomeronasal organ and the main olfactory systern process chemicals.
(B) summarize the debate over the role the vomeronasal organ plays in odor perception
(C) present some of the issues involved in the debate over what constitutes a pheromone
(D) propose a new definition of pheromones based on recent research
(E) argue that pheromones should be classified as a type of odorant

mbaiseasy · Accepted Answer

7. It can be inferred from the passage thatin classifying pheromones as a type of
odorant, the researchers referred to posit that

VNO is evidence used to counter that pheromones are perceived consciously. Hence, the researchers who believe that pheromones are odorant will not posit pheromones as processed through the VNO. Hence, B and C are out.

Answer: A (odorant are perceived consciously. Hence, pheromones must posses that characteristic as well)

The passage mentions about pheromones between the same specie but mentions nothing about members of diff specie. Since it wasn't mention then we cannot conclude that the researchers would think this. maybe but we have no proof. Don't go beyond the passage. Hence, D is out.

Another trick in RC is that something mentioned in the passage for example the statement in E will be linked to a different portion in the passage. The author mentioned that most believe that pheromones should elicit response. Then he mentions some posit that pheromones are odorant and another some posit that response should be unconscious. But stay true to what was linked to the researchers who believe pheromones are odorant. That's all we know they think is true. The other beliefs are attributed to a different set of people. This is a trap. Hence E is out.

A. pheromones are perceived consciously
B. most pheromones are processed by the VNO
C. most chemical signals processed by the VNO are pheromones
D. Pheromone perception does not occur exclusively between members of the same species.
E. pheromones do not always elicit a specific behavioral or physiological response

8. According to the passage, the fact that pheromones are processed by the VNO 
in many animal species has been taken as evidence of which of the following?

this is a type of question wherein we don't need to attack each choice. All you have to do is know what you learned from the passage before you go dive into the choices. We know that the VNO is an evidence against the claim that pheromones are odorant by showing that this system is separate from the system used for the sensation of smell. With this in mind, then go to look for that in the choices.

A is wrong. This is about proving or disproving something about pheromones.
B is wrong. VNO proves that they are distinct from each other.
C is wrong. VNO evidence is not about response or eliciting behavior, it's about the sensation of smell using a different organ.
D is the answer. It is obvious. bingo!
E is a trap. The VNO used to track prey refers to a non-pheromone. Read last sentence.

A. The accessory and main olfac-Tory systems are not separate
B. Odorants and pheromones are not distinct types of chemicals.
C. Odorants and pheromones both elicit a specific behavioral response.
D. Pheromones do not trigger conscious sensations of smell.
E. Pheromones aid animals in tracking prey.

9.The primary purpose of the passage is to

the master topic is Pheromone. Different beliefs of groups of people and evidences that show certain beliefs are not probably true and some arguments... Anything not about pheromones is obviously wrong. Hence, A and B are out.

D is out. The author was not able to pinpoint one sure definition.
E is out. The author seems to not lean to this theory.

Answer: c

D is out. The author was not able to pinpoint one sure definition.
E is out. The author seems to not lean to this theory.

Answer: c

A. compare and contrast the ways in which the vomeronasal organ and the main olfactory systern
process chemicals.
B. summarize the debate over the role the vomeronasal organ plays in odor perception
C. present some of the issues involved in the debate over what constitutes a pheromone
D. propose a new definition of pheromones based on recent research
E. argue that pheromones should be classified as a type of odorant

GMATNinja · Answer

I'm an airhead, and wrote this a few weeks ago when I didn't have internet access... but never posted it. There are lots of great responses here already, but I'll pile on, just in case it's helpful.

We're asked to state the  primary purpose . It's not enough to pick a choice that seems factually true. We need to pick the choice that best states the overall reason the author is writing the entire passage. And here's the structure of the passage:

There's no consensus among researchers regarding what qualifies as a pheremone. 
  Some researchers specify that pheremones must be unconsciously detected. 
  On the other hand, some researchers classify pheremones as odorants, which means that they must be consciously detected. 
  In many species, pheremones are processed by the VNO, which means that pheremones could be odorants but still be unconsciously detected. 
  The VNO also processes non-odorant chemicals, which can also trigger a behavioral response without any kind of odor.

This is a funky cloud of smells (and non-smells). The author is presenting one new fact after the next, repeatedly challenging the ways that researchers classify pheromones by bringing up evidence that would contradict those classifications. By the end of the passage, it seems like none of the classifications really work. So rather than leading us to any one definition, the author is writing this passage  in order to walk us through all of the ways that researchers attempt to classify pheromones . No wonder there's no consensus over what qualifies as a pheromone.

The author didn't write this entire paragraph just to tell us that the VNO and the main olfactory system are similar but different. Instead, author brings up this evidence to serve a bigger point: that the classifications researchers are using aren't very helpful. Eliminate (A).

The phrase "summarize the debate" is tempting. But like (A), choice (B) focuses too narrowly on the VNO. The passage isn't about the debate over VNO. It's about the debate over pheromone classifications. Eliminate (B).

Exactly! The author is walking us through the various classifications of a pheremone and citing evidence to support (or complicate) each one. (C) matches our understanding of the overall purpose, so we'll keep it around.

The author never  proposes a new definition . The author lists multiple definitions proposed by researchers, but doesn't state that any one of them is the one we should accept. At the end of the passage, the author hasn't shown that any of these definitions is satisfactory, and the debate goes on without consensus. That's why we eliminate (D).

Again, this is not why the author is writing the passage as a whole. It's just one of the researcher viewpoints that the author presents in order to lay out all the issues at play in this debate. Eliminate (E).

(C) Is the only good choice available, and it's a fine summary of why the author wrote this passage.

I hope this helps!

GMATNinja · Answer

Passage breakdown 
In passages that are one, long paragraph, it can be helpful to split the passage up. In this explanation, the passage will be split into three sections:

Section 1: from the start to “...classify pheromones as a type of odorant.” 
 Section 2: from “Evidence that pheromone responses…” to “...triggers sensations of smell.” 
 Section 3: from “But while the VNO does process…” to the end of the passage.

Here’s an example of how to breakdown this passage:

In the first section, the author  introduces a debate :

Are pheromones detected consciously or unconsciously?

In the second section, the author  presents evidence supporting the unconscious position:

One brain structure is used for consciously detecting odors, while another is used for unconsciously detecting pheromones.

In the third section, the author  introduces factors that muddy the waters:

The brain structure evidence isn't as clearcut as it seemed to be.

For more on the process of breaking down RC passages, check out  this article  and  our live RC videos .

Explanations for individual questions 
 
  Question 1  
  Question 3

AN225 · Answer

The official answer is ADE.
Why 1-A is correct? The question refers to that part
 In addition, the distinction between pheromones and odorants— chemicals that are consciously detected
as odors---can be blurry, and some researchers classify pheromones as a type of odorant 
So according to these researchers, pheromenes are perceived consiously.

Why 3-E is correct (very tricky, I first got it wrong):
The primary purpose of the passage is to
A. compare and contrast the ways in which the vomeronasal organ and the main olfactory systern
process chemicals. <<  too specific for the main purpose 
B. summarize the debate over the role the vomeronasal organ plays in odor perception <<  too narrow for the main purpose AND the main topic is pheromones, not VNO 
C. present some of the issues involved in the debate over what constitutes a pheromone <<  nice shell game, GMAT! Actually, it is stated in the beginning of the text that pheromens are a type of chemicals. That is it. The rest of the passage is how pheremones are processed and reacted by bodies. 
D. propose a new definition of pheromones based on recent research <<  no new definitions are discussed 
E. argue that pheromones should be classified as a type of odorant <<  not the best answer, but the only one left and it is the correct answer

BillyZ · Answer

GMATNinja , Could you help with question 1?

GMATNinja · Answer

Let's break down the given information:

We are told that "some researchers classify pheromones as a type of odorant." 
 Odorants are chemicals that are consciously detected as odors. 
 Thus, those researchers must believe that pheromones are consciously detected (or perceived) as odors.

This matches the given information exactly! Keep (A).

This is evidence that pheromone responses may NOT involve conscious odor perception. This contradicts the views of the highlighted researchers, so eliminate (B).

We don't know whether this is even true based on the information in the passage. Eliminate (C).

This idea is not discussed in the passage, so eliminate (D).

We are told that most researchers (including the highlighted researchers) agree that pheromones are "chemicals released by one individual of a species which, when detected by another individual of the same species, elicit a specific behavioral or physiological response." So the highlighted researchers would NOT agree with choice (E). Eliminate this one.

(A) is the best choice.

Boomshockalocka · Answer

GMATNinja

Hi GMATNinja, could you please help explain question 3? Why C is correct but not D?

Which part of the passage discusses what constitute a pheromone?

And doesn't the passpage propose a new definition, which "specify that the response to pheromones must be unconscious"?

Thanks so much.

NandishSS · Answer

HI  GMATNinja  ,  mikemcgarry  ,  egmat  ,  sayantanc2k ,  RonPurewal  ,  DmitryFarber  ,  MagooshExpert  (Carolyn),  ccooley  ,  GMATNinja Two ,  SarahPurewal

Can you please help me with above question?

Nikhil · Answer

Hello,

I tried the question and got it correct. Following is my analysis.

The relevant portion from the passage is "Evidence that pheromone responses  may not involve conscious odor perception comes from the finding  ... " and then presents the fact in question. So we can infer that the given fact is used as an evidence that pheromone responses doesn't involve conscious odor perception and option D reflects this. Hence I chose option D.

Let me know what you think ?

MagooshExpert · Answer

Hi NandishSS , Glad to help!

workout is correct here -- the relevant portion of the passage is: "Evidence that pheromone responses may not involve conscious odor perception comes from the finding that in many species, pheromones are processed by the VNO". So this tells us that the fact pheromones are processed by the VNO provides evidence that pheromones do not trigger a conscious sensation of smell, which matches choice D

Let me know if that isn't clear! -Carolyn

agrasan · Answer

Hi GMATNinja

Thanks for this great detailed explanation.

I had rejected option C only due to the word "constitute". My thinking was that the word means form/make (https://dictionary.cambridge.org/dictio ... constitute), if we look at the overall passage, I agree that it highlights different view points from different researchers with no common conclusion at the end but doesn't throw any light on what forms a pheromone so is it still fine to mark this option without paying an attention to the word "constitute"?

Please help me with this confusion.

GMATNinja · Answer

The link you provided gives the following example: "Women constitute about ten percent of Parliament." This does not mean that the women actively "created" or "built" ten percent of Parliament. Rather, it means that ten percent of parliament is made up of women.

In other words, when people come together to "form" a group, they are not building or creating some new thing apart from themselves. That's not the same as coming together to, say, build an external structure or to build a website or whatever, and you would not use "constitute" in that sense. You would not say, "The team worked for months to constitute a website." Building a website is not the same as forming a website, and forming a group is not the same as building/creating a pheromone.

The passage is concerned with what can be classified as a pheromone, and that fits with the first definition in the link you provided.

I hope that helps!

There is no consensus among researchers regarding what qualifies

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

There is no consensus among researchers regarding what qualifies

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards