Zoologist: Plants preferentially absorb heavy nitrogen from rainwater

Question

Zoologist: Plants preferentially absorb heavy nitrogen from rainwater. Heavy nitrogen consequently becomes concentrated in the tissues of herbivores, and animals that eat meat in tum exhibit even higher concentrations of heavy nitrogen in their bodily tissues. We compared bone samples from European cave bears of the Ice Age with blood samples from present-day bears fed meat-enriched diets, and the levels of heavy nitrogen present in these samples were identical. Thus, the prehistoric European cave bears were not exclusively herbivores.

Which one of the following, if true, would most strengthen the zoologist's argument?

Source: LSAT

Which one of the following, if true, would most strengthen the zoologist's argument?

(A) Plants can also absorb heavy nitrogen from a variety of sources other than rainwater.

(B) The rate at which heavy nitrogen accumulated in the blood of Ice Age herbivores can be inferred from samples of their bones.

(C) The same number of samples was taken from present-day bears as was taken from Ice Age cave bears.

(D) Bone samples from present-day bears fed meat-enriched diets exhibit the same levels of heavy nitrogen as do their blood samples.

(E) The level of heavy nitrogen in the bones of any bear fed a meat-enriched diet is the same as that in the bones of any other meat-eating bear.

Source: LSAT

niks18 · Answer

The conclusion is based on the evidence that " bone samples from European cave bears of the Ice Age with blood samples from present-day bears fed meat-enriched diets, and the levels of heavy nitrogen present in these samples were identical. "

Here bone samples have been compared with blood samples. So a possible strengthener will be if it is proved that bone samples of both the subjects are also equal.

(A) Plants can also absorb heavy nitrogen from a variety of sources other than rainwater.----- Irrelevant

(B) The rate at which heavy nitrogen accumulated in the blood of Ice Age herbivores can be inferred from samples of their bones.----- Out of scope. nothing has been discussed about herbivores

(C) The same number of samples was taken from present-day bears as was taken from Ice Age cave bears.----- Number of samples is not at issue here

(D) Bone samples from present-day bears fed meat-enriched diets exhibit the same levels of heavy nitrogen as do their blood samples.----- Correct. clearly states that bone samples of present day bears and ice age bears are similar in term of nitrogen content

(E) The level of heavy nitrogen in the bones of any bear fed a meat-enriched diet is the same as that in the bones of any other meat-eating bear.----- Irrelevant

akshaymalpani · Answer

The argument is that plants absorb nitrogen. Herbivores - i.e. plant eating animals - have higher concentration of nitrogen in their tissues and consequently, carnivores have a higher concentration of nitrogen than herbivores. When the bone sample of an ice age bear and the blood sample of a modern bear that was fed on a high meat diet were compared, the levels of nitrogen were equal in both samples. So, it stands to reason that the ice age bear must have had a meat component in its diet. Therefore, it could not exclusively be a herbivore. Hence the conclusion -  Thus, the prehistoric European cave bears (I'm using ice age bear to denote it) were not exclusively herbivores.

P.S. They are comparing bone sample and blood sample to arrive at the conclusion.

Which one of the following, if true, would most strengthen the zoologist's argument?

(A) Plants can also absorb heavy nitrogen from a variety of sources other than rainwater.
> Okay but how does this strengthen the conclusion? I think this is irrelevant.

(B) The rate at which heavy nitrogen accumulated in the blood of Ice Age herbivores can be inferred from samples of their bones.
> This talks about rate and we are concerned about level of nitrogen. The argument makes the inference of level not of rate of accumulation. Example, the argument says that the samples of both modern bear and ice age bear show that 20 units of nitrogen (I don't know the unit of measurement of gas, excuse me) were present. This statement says that the rate of accumulation - say 0.1% nitrogen is obtained from one meal by a bear - can be inferred. The argument is about whether the ice age bear is exclusively herbivorous. 
 
(C) The same number of samples was taken from present-day bears as was taken from Ice Age cave bears.
> Even if more number of samples were taken, the argument says nothing about whether the number of sample plays a role in determining the level of nitrogen.

(D) Bone samples from present-day bears fed meat-enriched diets exhibit the same levels of heavy nitrogen as do their blood samples.
> As mentioned above, we were comparing bone sample and blood sample. This strengthens the argument. Imagine that the statement was in the negative - bone samples and blood samples do not exhibit the same levels - then the conclusion would be weakened. When you measure like for like, the stronger the argument will be. If you are making a conclusion about about oranges, then you should use two oranges as your premises than one orange and one apple. D is correct.

(E) The level of heavy nitrogen in the bones of any bear fed a meat-enriched diet is the same as that in the bones of any other meat-eating bear.
> The argument is about ice age bear and modern bear. It isn't about bears.

Ttt2004 · Answer

why can't the answer be option b?
IT Talks about bone samples of ice age bears which strenghtens the argument.....

MartyTargetTestPrep · Answer

Here's (B).

(B) The rate at which heavy nitrogen accumulated in the blood of Ice Age herbivores can be inferred from samples of their bones.

Notice that (B) talks about the "rate at which heavy nitrogen accumulated" rather than the "levels of heavy nitrogen."

The support for the conclusion comes from a comparison of "levels" of heavy nitrogen. Information about the "rate at which heavy nitrogen accumulated" does not help to confirm that this comparison effectively supports the conclusion.

unraveled · Answer

Unless someone misses bone samples from Ice Age bears and blood samples, the question would not be tough to answer.
All other choices are either irrelevant or misdirect in approaching the core of the passage.

Raman109 · Answer

Understanding the argument - 
Zoologist: Plants preferentially absorb heavy nitrogen from rainwater. Heavy nitrogen consequently becomes concentrated in the tissues of herbivores, and animals that eat meat in turn exhibit even higher concentrations of heavy nitrogen in their bodily tissues. - Background Info.

We compared bone samples from European cave bears of the Ice Age with blood samples from present-day bears fed meat-enriched diets, and the levels of heavy nitrogen present in these samples were identical. Thus, the prehistoric European cave bears were not exclusively herbivores.

Which one of the following, if true, would most strengthen the zoologist's argument?

(A) Plants can also absorb heavy nitrogen from a variety of sources other than rainwater. - out of scope.

(B) The rate at which heavy nitrogen accumulated in the blood of Ice Age herbivores can be inferred from samples of their bones. - "rate" is out of scope, and option B is distorted.

(C) The same number of samples was taken from present-day bears as was taken from Ice Age cave bears. - out of scope.

(D) Bone samples from present-day bears fed meat-enriched diets exhibit the same levels of heavy nitrogen as do their blood samples. - ok.

(E) The level of heavy nitrogen in the bones of any bear fed a meat-enriched diet is the same as that in the bones of any other meat-eating bear. - this comparison is out of scope for us.

Zoologist: Plants preferentially absorb heavy nitrogen from rainwater

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Zoologist: Plants preferentially absorb heavy nitrogen from rainwater

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