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OG Verbal Review: Rats injected with morphine exhibit decreased

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OG Verbal Review: Rats injected with morphine exhibit decreased [#permalink]

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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
[Reveal] Spoiler: OA

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Re: OG Verbal Review: Rats injected with morphine exhibit decreased [#permalink]

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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
2) adrenal gland
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: OG Verbal Review: Rats injected with morphine exhibit decreased [#permalink]

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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: OG Verbal Review: Rats injected with morphine exhibit decreased [#permalink]

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New post 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: OG Verbal Review: Rats injected with morphine exhibit decreased [#permalink]

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New post 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?


Kudos please if you find this helpful :)

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Re: OG Verbal Review: Rats injected with morphine exhibit decreased   [#permalink] 10 Sep 2017, 20:52
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