[求助]OG12-89 那篇讲serotonin的文章，第8题里exclusively怎么理解？

stwlwl

RC的题，在坛里搜了半天也没找到。题目和63篇中第38篇是一样的。我的问题和下面的帖子是一样的。

http://forum.chasedream.com/dispbbs.asp?BoardID=25&ID=155750&replyID=&skin=0

文章比较长，如下

It was once believed that the brain was independent of metabolic processes occurring elsewhere in the body. In recent studies, however, we have discovered that the production and release in brain neurons of the neurotransmitter serotonin (serotonin: n.含于血液中的复合胺) (neurotransmitters are compounds that neurons use to transmit signals to other cells) depend directly on the food that the body processes.

Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood. We found that, immediately after the rats began to eat, parallel elevations occurred in blood tryptophan, brain tryptophan, and brain serotonin levels. These findings suggested that the production and release of serotonin in brain neurons were normally coupled with blood-tryptophan increases. In later studies we found that injecting insulin into a rat’s bloodstream also caused parallel elevations in blood and brain tryptophan levels and in serotonin levels. We then decided to see whether the secretion of the animal’s own insulin similarly affected serotonin production. We gave the rats a carbohydrate-containing meal that we knew would elicit insulin secretion. As we had hypothesized, the blood tryptophan level and the concentrations of tryptophan serotonin in the brain increased after the meal.

Surprisingly, however, when we added a large amount of protein to the meal, brain tryptophan and serotonin levels fell. Since protein contains tryptophan, why should it depress brain tryptophan levels? The answer lies in the mechanism that provides blood tryptophan to the brain cells. This same mechanism also provides the brain cells with other amino acids found in protein, such as tyrosine and Leucine. The consumption of protein increases blood concentration of the other amino acids much more, proportionately, than it does that of tryptophan. The more protein in the meal, the lower is the ratio of the resulting blood-tryptophan concentration to the concentration of competing amino acids, and the more slowly is tryptophan provided to the brain. Thus the more protein in a meal, the less serotonin subsequently produced and released.

8.    It can be inferred from the passage that which of the following would be LEAST likely to be a potential source of aid to a patient who was not adequately producing and releasing serotonin?

(A) Meals consisting almost exclusively of protein   

(B) Meals consisting almost exclusively of carbohydrates

(C) Meals that would elicit insulin secretion

(D) Meals that had very low concentrations of tyrosine

(E) Meals that had very low concentrations of leucine

OG解答如下

Inference

Since this question asks for an inference, the

answer is not directly stated in the passage; it

must instead be derived from the information

given. What kind of meals would NOT help a

patient with low serotonin levels? Meals that

increased serotonin would help the patient; meals

that lowered serotonin would not. According to

the last sentence in the passage, the more protein in

a meal, the less serotonin subsequently produced and

released. Th erefore, high-protein meals would be

LEAST likely to help the patient.

A Correct. Meals with very high levels of

protein would tend to lower serotonin and

thus to be less benefi cial for the patient with

inadequate serotonin levels.

B When rats ate a carbohydrate-containing

meal, serotonin increased (lines 25–29).

Th erefore, these meals would tend to raise

serotonin levels and so help the patient.

C In the study, meals that elicited insulin

secretion raised serotonin levels.

D Since tyrosine is an amino acid found in

protein, meals low in tyrosine would be low

in protein and so would tend to raise

serotonin levels and help the patient.

E Since leucine is an amino acid found in

protein, meals low in leucine would be low

in protein and so would tend to raise

serotonin levels and help the patient.

我想不通第8题，答案应该是   （A），我觉得是B。我的理解是越不包含carbohydrates的Meal,（least likely）越不能成为patient 需要的aid resource.我觉得问题可能出在对exclusively的理解。我理解exclusively的排他的，出去---的。A选项就应该是不包含蛋白质的meal,B就是不包含碳水的MEAL.

谁能帮我解答我哪里理解错了，谢谢！！！

[此贴子已经被作者于2009/10/8 0:56:13编辑过]

dandan2010

Thus the more protein in a meal, the less serotonin subsequently produced and released.这是文章的最后一句

who was not adequately producing and releasing serotonin，这是题目

因为protein会影响serotonin的release，所以这个人如果本来就没有足够的serotonin的话，就不能吃protein.但是问的是这个人最不可能吃什么，那么答案就是protein。

你一开始的定位就不对，这题根本就不关carbohydrates的事。5个选项只有protein是相关事物。

xiaohemage

 觉得这题是在考几种物质间的关系，不能说这题根本就不关carbohydrates的事，题目是要找不增加Serotonin的物质。含有exclusively也不是一定错啊

   Protain (tyrosine, leucine ) —     Tryptoplan +   Serotonin

                                                          +

                                                        Insulin

                                                           +

Carbonhydrates

quarboy

lz好像理解反了哦

A选项是说只包含protein的meal

B选项是说只包含碳水化合物的meal

偶查了字典 朗文是这么解释exclusively的：

only; and nothing/no one else

例句： this room is exclusively for women. 这间房间是供妇女专用的

所以A选项应该理解为Meals consisting almost only of protein

dandan2010

这题确实和carbohydrates无关，因为只有protein（因为只有P里面有concentration of competing amino acids使得boold 里面的  Tryptoplan没办法被运输到brain里面。

而三楼说的carbohydrates，是能产生insulin,而这个是会使brain tryptophan and serotonin levels up ,那么全文只有protein能做到是brain tryptophan and serotonin levels fell,当然其他都无关啦。

stwlwl

恩，后来发现是自己对exclusively理解错了。

谢谢各位～