GMAT RC

[greenwich]

There is no consensus among
researchers regarding what qualifies a
substance as a pheromone. While most
Line agree on a basic definition of pheromones
(5) 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
(10) 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
(15) 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
(20) 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
(25) 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 phero-
(30) mones work through the VNO. Conversely,
not all chemical signals transmitted via the
VNO quality as pheromones. For example,
garter snakes detect a chemical signal from
earthworms-one of their favorite foods-via
(35) the VNO, and they use this signal to track
their prey.

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

Please provide explanation with your answer.

[sahilchaudhary]

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.
E is a trap. The VNO used to track prey refers to a non-pheromone. Read last sentence.

[[email protected]]

OA[spoiler]C[spoiler]
A:We are indeed comparing the functions. But, It isn't the main purpose. This option is a good contender.
B:There is no debate over the role of verenosal organ.
C:Read the first line. So,there is a debate on constitution of pheromone.
D: Defination! Out of scope
E: Not the central idea
Regards,
Mukherjee

[bubbliiiiiiii]

I agree with Sahil to a certain extent that such questions don't need an attack on the answer options. However, its always advisable that we read all the options.

I will pick C over D.

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.

The passage suggests the ways of VNO and oflactory system to distinguish between the concious and unconcious odour routes/methods. Thus, incorrect.

B. summarize the debate over the
role the vomeronasal organ
plays in odor perception

Passage presents this as an fact rather than debate or question the role of VNO. Thus, incorrect.

C. present some of the issues
involved in the debate over
what constitutes a pheromone

Passage begins with defining what a pheromone is and then goes with exceptions, citing examples of few animals. Thus, passage summarizes the different views of what constitutes a pheromone.

D. propose a new definition of
pheromones based on recent
research

Author doesnot propose a new definition rather tries to reconcile the debate.

E. argue that pheromones should be
classified as a type of odorant

Out of scope.

Hop it helps.