keysersozebrook wrote:
From 3rd to 5th questions, I chose wrong all of them: D, C, and B. Could anybody kindly tell me how you find the right answers for these three questions? Many thanks!
4. The information in the passage indicates that if human beings were given a drug that inhibits the action of serotonin, which one of the following might be expected to occur?
(A) Subjects would probably show a preference for carbohydrate-rich snacks rather than protein-rich snacks.
(B) Subjects would probably become sleepy after eating a carbohydrate-rich meal.
(C) Subjects would be more likely to lose weight than before they took the drug.
(D) Subjects’ blood tryptophan levels would probably increase.
(E) Subjects’ desire for both carbohydrates and proteins would increase.
Question type: Indicate---> Inference
For finding the answer for this I refer to para 1, last line and para 4.
The passages states that drugs that inhibit the action of serotonin have the opposite action to that of serotonin like drugs.
So carbohydrate craving actually increases. Further in Para 4 it is mentioned that serotonin facilitators actually reduce carbohydrate craving by prolonging serotonin's action. Subjects feel sleepy after given a carbohydrate meal and the opposite is true for people who take drugs that block serotonin. With this understanding, I shall try to eliminate options and try to reach the correct answer.
A) Subjects would probably show a preference for carbohydrate-rich snacks rather than protein-rich snacks.
Seems correct. But, we might get a doubt whether is there any craving for protein snacks at all, which is not explicitly stated in the passage. If it is present, is it more or less or equal? I'll try to eliminate others or will mark other option, if found to be more convincing than this is.
B) Subjects would probably become sleepy after eating a carbohydrate-rich meal.
Opposite. INCORRECT
They become refreshed and invigorated.
C) Subjects would be more likely to lose weight than before they took the drug.
Again opposite. INCORRECT.
They would more likely to gain weight. To increase or to reach the required levels of serotonin in brain, people excessively crave for carbohydrate diet and probably take more carbohydrates and gain weight.
D) Subjects’ blood tryptophan levels would probably increase.
No information given. We don't know what increases the blood tryptophan levels with the information given in the passage. We were only given Tryptophan----->Serotonin but no information whether low serotonin levels lead to more tryptophan.
INCORRECT
(The passage explicitly states that, when the carbohydrate level in the blood stream increases, insulin is produced and amino acids other than tryptophan are taken up by peripheral tissues. This in turn indirectly increases the "relative tryptophan levels".
Its actual levels or its levels prior to intake of carbohydrates are the same. Its just that others are taken up and it seems to be the one that exists.)
E) Subjects’ desire for both carbohydrates and proteins would increase.
Desire for carbohydrates increases, but protein's; not mentioned. So I would rule out E too.
INCORRECT
Left with A. I would refer to the experiment given in the third passage.
"On the other hand, when rats are given drugs that interrupt serotonin-mediated neurotransmission, their brains fail to respond when carbohydrates are eaten, so the desire for them persists." I will try to draw an analogy so that I would be even more confident in marking this. The question stem says "might", so no harm.
"Normally" rats alternate between protein and carbohydrate. But when given drugs that inhibit serotonin action, their brains fail to respond. Desire persists, so we can infer that given more carbohydrate they will continue to eat until the serotonin level in the brain reaches to that level, which says to brain, it's enough. So, it's clear they don't care if we feed them more protein snacks.
A.