Q13 - Aminal feed should not include

[smiller]

Question Type:
Weaken

Stimulus Breakdown:
Premises:
1. Rats in a study that were fed GM potatoes for 30 days developed intestinal deformities and a weakened immune system.
2. Rats in the study that were fed a normal diet of non-GM foods did not have problems.

Conclusion:
Animal feed should not include genetically modified plants.

Answer Anticipation:
This argument leaves out a great deal of information that is needed to guarantee the conclusion. Maybe rats normally develop intestinal deformities and a weakened immune system if they eat potatoes. Maybe the rats were fed something else along with the potatoes that caused those problems, or maybe the first group of rats was more prone to the problems in the first place.

Even if the GM potatoes did cause the problems, can we conclude that animal feed should not include any type of GM plant? Can we conclude that any quantity of GM plant should be avoided, even a small quantity, for a short duration? The correct answer could highlight any of these gaps in the argument.

Correct Answer:
(A)

Answer Choice Analysis:
(A) This is correct. If rats normally don't eat potatoes then it means we have a study where one group is eating a normal diet, and the other is eating an abnormal diet. It's very possible that this would cause the problems regardless of whether or not the potatoes were genetically modified.

(B) This comparison is irrelevant. Why do we care if the rats ate less potatoes toward the end of the study? This doesn't weaken. Intestinal deformities could cause the rats to eat less, no matter what was causing the deformities.

(C) Intestinal deformities at birth are irrelevant. The premises involve deformities that developed during the study.

(D) This is tempting, but doesn't weaken as much as (A). It eliminates one factor that might cause the GM potatoes to harm the rats. However, it still leaves open the possibility that the GM potatoes harmed the rats in some other way, so it's not a great weakener.

(E) Like (D), this might be tempting at first glance, but doesn't necessarily weaken. A study could demonstrate that something is harmful without the researchers being able to explain exactly how it causes harm. We don't know exactly how gravity works, but we know that jumping out of an airplane without a parachute is likely to be harmful.

Takeaway/Pattern: When the stimulus has multiple flaws it can be easy to anticipate a correct answer, but you may still have to decide between two or more tempting answer choices. The incorrect answers will leave too many possibilities open.

#officialexplanation

[mansour.yael]

Why is answer A and not C?

Wouldn't C provide an alternate explanation (intestinal deformities are NOT uncommon among lab rats), and thus weaken the argument?

[susan.tmpltn]

Hey there,

Someone can correct me if I'm wrong, but notice how in the stimulus it says the lab rats were fed genetically modified potatoes, but we don't know what type of food the other group of rats are eating. They very well could be eating potatoes, or maybe, they aren't even eating potatoes at all. Maybe they are eating broccoli because that's part of their normal diet.

Answer choice A captures this gap in the argument. If potatoes are not normally a part of their diet, then maybe they are developing intenstinal problems because they can't digest potatoes genetically modified or not.

Answer choice C is definitely tempting to me as well, but notice how it doesn't really make an impact on the argument. If C were true, why didn't this effect the group with normal diets? Either way, C doesn't have the same effect as A.

Does that make sense?

[Mahdiall]

C is wrong because we're not concerned about lab rats who were born with intestinal deformities. This wouldn't weaken the argument that GMO feed causes these intestinal deformities. Notice how in the stimulus, the author is talking about the rats who "developed intestinal deformities" not the ones who were born with intestinal deformities.

[asafezrati]

Answer choice C is definitely tempting to me as well, but notice how it doesn't really make an impact on the argument. If C were true, why didn't this effect the group with normal diets? Either way, C doesn't have the same effect as A.

Does that make sense?

Absolutely. C doesn't give an explanation for a difference between the groups. It actually describes something that is generally true of the super-group to which all of the mentioned mice belong to.
I suggest that anyone who finds this one tempting see to it that next time it will be an easy kill. The conclusion is based on a comparison between the two groups, and this answer choice doesn't make any distinction between the two.

This answer choice also has other problems, as the above poster noted.

Here's a full/quick explanation:

(GMO stands for Genetically Modified Organism. I picked up the term at chipotle)

Premise: a group of rats fed only GMO potatoes tended more to develop intestinal deformities and a weakened immune system than another group fed non-GMO foods.
Conclusion: Animal feed shouldn't include GMO plants.

There are plenty of assumptions here which can be hurt in order to produce a weakener. The potato part is pretty vague though, because we aren't told whether the non-GMO group was given potatoes. But if they aren't a part of their normal diet, then perhaps feeding lab rats this diet caused the problem in that group, and the GMO part is irrelevant. So A isn't amazingly strong, but it's good.

B - I don't know how the time difference affects anything, so this one is out.
C - Gives information about all the lab rats' health tendencies. So how come there WAS a difference between the two groups? OUT!
D - Nutritional values are not necessarily the only difference between GMO and non-GMO plants. Maybe some bacteria are involved or some other thing that nutritional value doesn't account for.
E - I stopped reading after "were unable to explain". This has no effect.