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# Rats injected with morphine exhibit decreased activity of the immune

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Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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11 Mar 2016, 23:47
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Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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12 Mar 2016, 21:49
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Vyshak wrote:
Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams

Hi,

a tough Q, which becomes even more complicated due to scientific terms used and the reasoning..

PARA in simple terms-

Rats adminestered Morphine are seen having two effects.
1)decreased activity of the immune system
2) heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands.
The scientists hypothize from this that Morphine does 2, which results in 1..

what should choice consist of-

1) morphine injected
3) change in level of immune system/blood levels

lets see the choices

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
The experiment is about rats with normal blood levels of cortico.. we do not know the relation in high levels. does it stagnates after a certain level?

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again
Morphine is an important part of the experiment. the choice is missing that

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections
Morphine is an important part of the experiment. the choice is missing that

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses
this CORRECTLY does the following..
1) uses morphin
2) connects glands to it to see the reaction in absence of glands
this will tell us if it is gland which is responsible or not

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams[/quote]
Morphine is an important part of the experiment. the choice is missing that

D
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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13 Mar 2016, 01:00
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Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids.

The subjects- rats- already have reduced immunity. This option confirms that corticosteroids affect immunity but it does not confirms or rejects the conclusion that morphine affects immunity.How can we confirm a cause when the effect is already present?

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again.

This option may help confirm that adrenal glands affect immunity by releasing corticosteroids but this option will not help us understand the effect of morphine.

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections.

This option may help confirm that corticosteroids affect immunity but this option will not help us understand the effect of morphine.

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses

Correct as explained below.

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams.

The argument is about effect of morphine and not about any other drug.

Cause and effect type CR.

The conclusion Morphine ----> affects adrenal glands-----> release corticosteroids------> reduced immunity.

We are not sure about the above 'chain' of cause and effect because it is possible that Morphine ------directly----> reduces immunity .
Just because the rats in the sample had heightened levels of corticosteroids does not mean that morphine helped induce the heightened levels of corticosteroids.
The best way to confirm the conclusion or reject the conclusion will be remove the adrenal glands and check for immunity levels.
Break the chain and confirm the effect!

Hence, D is correct.

Hope the above is useful.

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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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18 Aug 2017, 02:26
D is correct - If the immune system responses decreased after the morphine injections in this experiment, the hypothesis that it was by stimulation of the adrenal glands that morphine reduced immune-system activity would be undermined. But if no decrease in immune-system responses occurred, the hypothesis would be confirmed.
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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10 Sep 2017, 20:52
Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis? < -- Evaluate Question

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
- completely ignores any decrease in activity of the immune system -- that matters a lot here

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again
- where is morphine mentioned here? plays integral role in decreasing activity of the immune system

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections
- same as "A"

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses
- correct as is

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams
- same as "B"

idea here is that MORPHINE uses CORTICOSTEROIDS to REDUCE the immune response. since this is an EVALUATE question, we need something that can prove this idea.
> D = correct b/c if you remove the adrenal glands, how would the morphine stimulate corticosteroid growth to reduce the immune response?

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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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09 Mar 2018, 02:50
Choices B & D are close contenders. Choice B did not mention about injecting morphine which is critical to evaluate its relation with adrenal glands. We are left with only right choice D.
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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23 May 2018, 15:12
chetan2u wrote:
Vyshak wrote:
Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams

Hi,

a tough Q, which becomes even more complicated due to scientific terms used and the reasoning..

PARA in simple terms-

Rats adminestered Morphine are seen having two effects.
1)decreased activity of the immune system
2) heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands.
The scientists hypothize from this that Morphine does 2, which results in 1..

what should choice consist of-

1) morphine injected
3) change in level of immune system/blood levels

lets see the choices

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids
The experiment is about rats with normal blood levels of cortico.. we do not know the relation in high levels. does it stagnates after a certain level?

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again
Morphine is an important part of the experiment. the choice is missing that

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections
Morphine is an important part of the experiment. the choice is missing that

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses
this CORRECTLY does the following..
1) uses morphin
2) connects glands to it to see the reaction in absence of glands
this will tell us if it is gland which is responsible or not

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams

Morphine is an important part of the experiment. the choice is missing that

D[/quote]

I have a problem with D, can someone please help me out? None of these answers really resolve the issue for me. D states " Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses".

My logic, if we remove the adrenal gland to test whether or not that is the culprit, we are not testing for control since some other factor could be changed simply by removing the adrenal gland. Nothing states that the adrenal gland is the ONLY part responsible for corticosteroids, nor is there anything that states whether or not removing the adrenal gland of a rat will allow for a full-proof test of the logical conclusion, what if removing the adrenal gland changes something else in the rat? Simply testing for the circumstances by adding or removing something which is somewhat correlated does not logically prove an outcome, however, if they took two separate sample populations one with and one without morphine that would prove the outcome. Can someone please help here?
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Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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Updated on: 03 Jun 2018, 07:21
Stimulus
1) Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. Morphine is bad for immune system
2) These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. - Same rats--->exhibited heightened blood levels of "C"----->chemicals secreted by the adrenal glands.
3) Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.---------> morphine is by stimulating the adrenal glands to secrete "additional C" into the bloodstream

Question Stem:-
Required:-Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

Option D is rightly attaining this objective - "Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses"

Analysis:- Some experiment which proves that morphine is NOT stimulating the adrenal glands. If adrenal glands are removed & if "additional C" is not present after injecting morphine then what does this explain. In fact morphine was stimulating the adrenal glands to secrete "additional C" into the bloodstream which was interfering with the immune responses of the rats.

jennpt - pls provide your feedback
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Originally posted by CAMANISHPARMAR on 02 Jun 2018, 00:35.
Last edited by CAMANISHPARMAR on 03 Jun 2018, 07:21, edited 1 time in total.
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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02 Jun 2018, 04:43
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Hi CAMANISHPARMAR

Overall, your notes and thought process look good. You have successfully identified that we need more information to prove the first link in the hypothesized "path": morphine -> stim. adrenals to make increased C -> increased C messes up immune system.
Just be careful that this is an Evaluate question stem, so we don't necessarily have to disprove it. Right now your Analysis notes look like this is a Weaken question.
However, we just want to get some info about whether the hypothesis could be right or wrong. So in your analysis note "Some experiment which proves that morphine is NOT stimulating the adrenal glands." ... I would just modify this to "Some data that describes WHETHER (IF) morphine is stimulating the adrenal glands."

Make sense?

Best, Jenn
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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02 Jun 2018, 05:04
jennpt wrote:
Hi CAMANISHPARMAR

Overall, your notes and thought process look good. You have successfully identified that we need more information to prove the first link in the hypothesized "path": morphine -> stim. adrenals to make increased C -> increased C messes up immune system.
Just be careful that this is an Evaluate question stem, so we don't necessarily have to disprove it. Right now your Analysis notes look like this is a Weaken question.
However, we just want to get some info about whether the hypothesis could be right or wrong. So in your analysis note "Some experiment which proves that morphine is NOT stimulating the adrenal glands." ... I would just modify this to "Some data that describes WHETHER (IF) morphine is stimulating the adrenal glands."

Make sense?

Best, Jenn

Thank you for inputs. Makes sense. Nice explanation, Thanks again!!
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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11 Jul 2018, 08:05
in a causal argument, A appear when B appears. and the conclusion is A cause B.
we have many ways to weaken
1. B cause A, not A cause B
2. B dose not appear when A appear.
3. another thing cause B.

if we prethink, we can prethink one of above three. or at best, prethink all of three above
read choice D. D is match our prethink. if B dose not happen when A dose not happen, we have a strenthener. choice D is good.

evaluate question is similar to weakening question. we need to prethink the condition which fallsify argument before going to anserwer choices. the correct answer is the one which "potentially" weaken.

this is very hard problem because the prethink process dose not take us to the case " if A dose not appear, B dose not/dose appear, we have strengthen/weaken fact".

if prethinking dose not take us to a position which is close to the correct answer choice, the question is hard. if prethinking take us to the position close to the answer choice, the question is easy. gmat use statistics to realize which question is hard or easy and make the hard/easy questions.
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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19 Jul 2018, 03:18
Vyshak wrote:
Rats injected with morphine exhibit decreased activity of the immune system, the bodily system that fights off infections. These same rats exhibited heightened blood levels of corticosteroids, chemicals secreted by the adrenal glands. Since corticosteroids can interfere with immune-system activity, scientists hypothesized that the way morphine reduces immune responses in rats is by stimulating the adrenal glands to secrete additional corticosteroids into the bloodstream.

Which of the following experiments would yield the most useful results for evaluating the scientists’ hypothesis?

(A) Injecting morphine into rats that already have heightened blood levels of corticosteroids and then observing their new blood levels of corticosteroids

(B) Testing the level of immune-system activity of rats, removing their adrenal glands, and then testing the rats’ immune-system activity levels again

(C) Injecting rats with corticosteroids and then observing how many of the rats contracted infections

(D) Removing the adrenal glands of rats, injecting the rats with morphine, and then testing the level of the rats’ immune-system responses

(E) Injecting rats with a drug that stimulates immune-system activity and then observing the level of corticosteroids in their bloodstreams

+1 D. Cover the idea of whole passage.
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Re: Rats injected with morphine exhibit decreased activity of the immune  [#permalink]

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20 Oct 2018, 06:39

Argument Evaluation

Situation Rats injected with morphine exhibit decreased immune-system activity and increased levels of corticosteroids, which are secreted by the adrenal glands and can interfere with immune-system activity.

Reasoning What further experiment would help determine whether morphine reduces immune responses in rats by stimulating the adrenal glands to release more corticosteroids? Contrary to the scientists' hypothesis, the experimental results might have occurred because the morphine injections directly reduced immune-system activity. Or the injections might have blocked some mechanism that reduces corticosteroid levels in the blood, even if the morphine did not stimulate the adrenal glands to produce more corticosteroids. To evaluate whether the scientists' hypothesis is more plausible than these rival hypotheses, it would be helpful to know whether similar experimental results would occur after morphine injections even if adrenal gland activity did not change.

Option D is Correct. If the immune system responses decreased after the morphine injections in this experiment, the hypothesis that it was by stimulation of the adrenal glands that morphine reduced immune-system activity would be undermined. But if no decrease in immune-system responses occurred, the hypothesis would be confirmed.

Why option A, B, C & E are incorrect:-

A - Morphine could stimulate the adrenal glands of rats with normal corticosteroid levels to produce more corticosteroids, whether or not it does so in rats whose corticosteroid levels are already heightened.

B - Such an experiment would not involve morphine and thus would not help to determine how morphine affects immune-system activity in rats.

C - Whether or not rats contract infections may not reliably indicate their levels of immune-system activity.

E - Even if the mechanism by which a drug other than morphine increases immune-system activity were discovered, this discovery would not necessarily reveal the mechanism by which morphine reduces immune-system activity.
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Re: Rats injected with morphine exhibit decreased activity of the immune   [#permalink] 20 Oct 2018, 06:39
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