Critical Reasoning

I think it should be D.

We wanna support the hypothesis, we need to closely support the reasoning process of it.

the issue here is to discuss why the herb, not that closely related group, can grow in that extremly hostile environment. Therefore C out.

and there's no clue in the CR problems about the growing stage of that herb,It just said that the herb produces that particular kind of animo acid without mentioning the stage in which the production happens. Therefore, E cannot support the hypothesis.

Only D presents a plausible feedback for whether the hypothesis could be true---whether the animo acid produced by the herb renders the metals in oil inert.

Hi Ron,

I have seen different answers of the different versions for this question still on solid explanation. I chose C.
what should be the correct answer as per you?

Thanks Ron!

lunarpower wrote:

Kajiabeat wrote:the issue here is to discuss why the herb, not that closely related group, can grow in that extremly hostile environment. Therefore C out.

no. if you have a group of other plants that are "closely related" and that have the same abnormal ability, then seeing the same correlation across the board in those other plants definitely strengthens the association.

analogy: let's say that one person develops cirrhosis of the liver and is a heavy drinker; therefore, we hypothesize that heavy drinking causes cirrhosis of the liver.
if we examine a bunch of other people with cirrhotic livers who are similar to the first person and, sure enough, they are all heavy drinkers as well, that is definitely strong support for the idea that heavy drinking causes cirrhosis.

Only D presents a plausible feedback for whether the hypothesis could be true---whether the animo acid produced by the herb renders the metals in oil inert.

the argument is about the possible influence of histidine. choice (d) does not mention histidine at all, and so it is irrelevant.
(in your interpretation, you are assuming that the histidine is what renders the metals inert. however, you have manufactured that association out of thin air; there is no support for it in the actual text of that answer choice.)

Hi Ron,

I get what you see in C,but it's still hard for me to see D not to be a supportive evidence.

The scientist's logic is : H produced by the plant makes the metal inert---> production of H is the reason why the plant can live in metal-rich environment.

D says sth to suggest that the experiment happens in test tube can also happen in soil, which make one step farward from the expriment to the speculation, moving the chemical effect from lab to real life,and therefore inhance the possibility that the speculation is right.

about the wording of"over a period", I think this phrase is put there just to make the statement more prudent, as in test tube, there's liquid, and in soil there's solid environment in which chemical effect may take more time to show.


Also, there must be something else in common among those close-related group of plants but none of them are mention in this issue maybe because those are not considered relavant with the anti-metal ability of these plants.

another thing is, if we choose C, we don't need to know the H will or will not render metals inert, because if lots of plants in the group produce big quantity of H, and at the same time they all can survive the metal-rich soil, these information are enough to establish the correlation. But what we need to support is the causal relationship between the production of H and the anti-metal ability of that herb/ that group of herb, that's why the origal CR question give us an very important information about H----it renders metal inert.

I think, the conclusion is not "the production of H", but the "production of such kind(anti-metal) of chemical" because what's H is like is just said in the conclusion's preceding sentence.

repeated.

Hi Ron
A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. Possibly, therefore, the herb's high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

D. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic

Doesnt D strengthen the argument if we interpret it as saying that the soil becomes suitable for other plants that find the metal in the soil toxic .
I think D is palatable if we consider the following situation
1) Herb grows for sometime
2) Soil becomes suitable for other plants that earlier found the metals Toxic
This means Something has rendered the metals inert
Therefore , The reason is more likely to be Histadine

lunarpower wrote:
should be (c) -- scroll up two posts for the explanation.

Ron, with all respect to ur point of view, let me suggest my humble opinion too ))

the conclusion here is "therefore, the herb's high histidine production is what allows it to grow in metal-rich soils"

please pay attention, that the q.stem stresses the point of correlation between high histidine production and the growing of the plant.

so,
C. others of the closely related group of plants are also found to produce histidine in
large quantities

C sounds nice. it is great that other plants produce histidine in large quantities, but it does NOT prove that this anyhow helps to grow that plants.

so, C is out of scope

now E
E. the concentration of histidine in the growing herb declines as the plant approaches
maturity

see,that here we can find that herb grows using its concentration of histidine, and as it reaches its maturity there is no need in histidine anymore (that is why to the end of this process the concentration is down)

I think it should be D as well. The lab experiment shows that histidine makes the metals inert. This will only be enhanced by D.

Komal,

If the concentration of histidine declines on maturity, that should mean that the plant starts to die whereas the agrument doesnt say so atall.

My logic for picking up option D was:
Since histidine makes the metal inert, so, once this particular herb is cultivated in the soil rich in toxic metal, the herb would turn the metal in soil inert making it fit for cultivation of other plants. So, I picked option D. Please tell me the flaw in my reasoning.

thanks in advance.

-------------------------------------------------------
D. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic
Incorrect : This might actually weaken the argument by stating that adaptability of the herb to toxic soil is the reason why the herb thrives in metal-rich soil.

E. the concentration of histidine in the growing herb declines as the plant approaches maturity
Correct : It is stated in the hypotheses above that histidine allows the herb to GROW. It means that as long as the herb is growing, histidine is high and as the herb approaches MATURITY the concentration of histidine declines.

komal wrote:

geet wrote:Which of the following most logically completes the argument?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. Possibly, therefore, the herb�s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

A. histidine is found in all parts of the plant�roots, stem, leaves, and flowers
Incorrect : In what parts of the plant is histidine found is irrelevant to the scope of the argument.

B. the herb�s high level of histidine production is found to be associated with an unusually low level of production of other amino acids
Incorrect : This might actually weaken the argument by stating that LOW LEVEL OF OTHER AMINO ACIDS is actually responsible for making the metal in the soil chemically inert.

C. others of the closely related group of plants are also found to produce histidine in large quantities
Incorrect : Issue is about this particular herb and not about OTHERS IN THE GROUP.

D. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic
Incorrect : This might actually weaken the argument by stating that adaptability of the herb to toxic soil is the reason why the herb thrives in metal-rich soil.

E. the concentration of histidine in the growing herb declines as the plant approaches maturity
Correct : It is stated in the hypotheses above that histidine allows the herb to GROW. It means that as long as the herb is growing, histidine is high and as the herb approaches MATURITY the concentration of histidine declines.

Hope this helps : )

My answer is either letter 'A' or 'E'

How about when the so called plant roots are boiled or cooked, is the concentration of histidine also declines?