ged-26-9

Q7 to Q9

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 pas-

sage 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

答案是e，可是我觉得是C，请问有明白的么？