Critical Reasoning

Mice that have been given morphine are very likely to develop blood poisoning because
bacteria that normally reside in the intestine typically respond to morphine by migrating
into the bloodstream. However, when mice are given both morphine and the new drug
naltrexone, blood poisoning is much less frequent, although it does still occur. These results
provide support for researchers' prediction that naltrexone will turn out to be toxic to
certain types of bacteria.

Which of the following, if discovered to be true, would
most seriously weaken the support for the researchers' prediction?

A. After being administered to mice, naltrexone does not pass from the bloodstream into the
intestine.
B. Naltrexone inhibits morphine from triggering the migration of intestinal bacteria into the
bloodstream.
C. Mice that have been given naltrexone but not morphine have no greater risk of developing
blood poisoning than do mice that have not been given either substance.
D. The increased risk of blood poisoning is not the only harmful effect on mice of being given
morphine.
E. Conditions other than the presence of intestinal bacteria in the bloodstream can cause
blood poisoning in mice

zaarathelab wrote:Mice that have been given morphine are very likely to develop blood poisoning because
bacteria that normally reside in the intestine typically respond to morphine by migrating
into the bloodstream. However, when mice are given both morphine and the new drug
naltrexone, blood poisoning is much less frequent, although it does still occur. These results
provide support for researchers' prediction that naltrexone will turn out to be toxic to
certain types of bacteria.

Which of the following, if discovered to be true, would
most seriously weaken the support for the researchers' prediction?

A. After being administered to mice, naltrexone does not pass from the bloodstream into the
intestine.
B. Naltrexone inhibits morphine from triggering the migration of intestinal bacteria into the
bloodstream.
C. Mice that have been given naltrexone but not morphine have no greater risk of developing
blood poisoning than do mice that have not been given either substance.
D. The increased risk of blood poisoning is not the only harmful effect on mice of being given
morphine.
E. Conditions other than the presence of intestinal bacteria in the bloodstream can cause
blood poisoning in mice

only B & E seems relevant.
I might go with B because...
The question says...

1-morphine triggers intestinal bacteria & this bacteria in blood causes poisoning
2-if morphine & naltrexone given, blood poisoning is much less frequent
so it concludes that this naltrexone acts on that bacteria.

But here what if, instead of this naltrexone acting on that bacteria, if it inhibits morphine's ability to trigger intestinal bacteria. Then it is wrong to say that naltrexone is toxic to bacteria.
This is covered only in option B.

user123321

we have "that naltrexone will turn out to be toxic to certain types of bacteria. " or in short, naltrexone (N) is toxic to bacteria

we need to weaken what we have ,i.e. that the process above is not the result of N poisoning of bacteria

so, lets look at B-

B. Naltrexone inhibits morphine from triggering the migration of intestinal bacteria into the
bloodstream.

here we see that N affects on bacteria not by poisoning it, but by inhibiting of morphine from triggering bacteria

Instead of turning out to be toxic to certain types of bacteria, the naltrexone inhibit the bacteria to migrate into the bloodstream. Choice B explain the result of experiment and also refute the prediction of researchers.

OA is B

Even I was stuck between B and E . I dint choose E but couldnt agree to B as well . According to the premise , since morphine intervenes with the bacterial activity in intestine , the blood is poisoned . As per choice B , The new drug prevents morphine from doing so , which means that when both are administered together there should be no poisoning . But in the second line of the premise , towards the end it says ' The poisoning is reduced but not altogether deterred' . So do you still think B can be a viable option ?

What is the source of the question ?

Deepthi Subbu wrote:Even I was stuck between B and E . I dint choose E but couldnt agree to B as well . According to the premise , since morphine intervenes with the bacterial activity in intestine , the blood is poisoned . As per choice B , The new drug prevents morphine from doing so , which means that when both are administered together there should be no poisoning . But in the second line of the premise , towards the end it says ' The poisoning is reduced but not altogether deterred' . So do you still think B can be a viable option ?

What is the source of the question ?

E says there are other factors which can cause blood poisoning in mice.
So in a way this supports the argument which says "the blood poisoning can be reduced but not altogether deterred". this just explains why it cannot be completely reduced. hence it is not weakening.

user123321

Conc: Naltrexone - toxic to bacteria

What if it isn't and the effects are because of something else ? Hands down B. Gives an alternate reason why they aren't toxic to bacteria and how the blood poisoning is controlled.

Assumption: Naltrexone is destroying the bacteria which has come into the bloodstream.
Option B gives a reason other than the assumption stated above. Hence weakening the assumption

OA is B

Morphine leads to blood poisoning in Mice because it makes bacteria migrate from intestine into the bloodstream while Morphine with naltrexone leads to blood poisoning much less frequently.
Conclusion: Naltrexone kills some types of bacteria.
To weaken the researcher's prediction we need to hit the conclusion. We need to prove that Naltrexone doesn't kill bacteria but it in some other way reduces the chances of food poisoning.
Choice B is one of those statements that could weaken the conclusion that Naltrexone kills bacteria. Hence, B is the answer.
Q.2)A. This is surely not the concern of the passage. The passage mostly talks about the incidences of existence of black hole and not why it is rare.
B. The author didn't criticize any method. Moreover, no method to gather data has been mentioned.
C. This is the best possible answer to the question. The phenomenon mentioned is the "black hole" and incidences are talked about throughout the passage. Hence, C is the answer.
D. Only one natural phenomenon is particularly mentioned i.e. "black hole".
E. The explanation is not widely accepted. So, E can't be the answer.