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Director
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A certain cultivated herb is one of a group of closely [#permalink]
 18 Dec 2006, 19:43
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A certain cultivated herb is one of a group of closely related plants that thrive in soil withhigh concentrations of metals that are toxic to most other plants. Agronomists studyingthe 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, theherb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesisthat would gain support if ______.
A. histidine is found in all parts of the plant—roots, stem, leaves, and flowers
B. the herb’s high level of histidine production is found to be associated with anunusually low level of production of other amino acids
C. others of the closely related group of plants are also found to produce histidine inlarge quantities
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic
E. the concentration of histidine in the growing herb declines as the plant approachesmaturity
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Manager
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I think it shud be D
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Director
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Is it C?
The same hypothesize applies to related group of plants
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VP
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I got C.
A, B and E are irrelevant/out of scope.
D says that cultivation of the herb in a metal-rich soil will make the soil suitable for the growth of the group of plants it belongs to, but provides no explanation as to WHY the herb can thrive in a metal-rich soil.
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Director
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I am going for C. The question states: Possibly, therefore, theherb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesisthat would gain support if ______.
So, C, which talks about growth of other plants in the same soil, supports this hypothesis.
EDITING:
Changing to D. The previous argument states that the metals become inert in lab conditions. So what proves they become inert outside the lab where the plants are grown?
Last edited by mbagal1 on 19 Dec 2006, 06:16, edited 1 time in total.
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VP
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We have to prove that the production of histindine is inert in nature and its contarsting nature against metals.
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic .
This is a test where the plant produces a chemically inert amino acid which repels the mettalic nature of the soil there by allowing regular plants to grow..Phew...
D it is
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VP
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isn't C weakening the whole idea? first, it doesn't say that those closely related group of plants produces histidine in the SAME soil, meaning with toxic metals.... so what if they have high level of it... if it isn't in the same soil, how can we support the hypothesis that this "h" crap helps the herb to thrive.
D, on the other hand, says that over longer period of time this "h" crap sucks in the toxic metals and allows the the soil to be suiteable for the plants that aren't resistant to the toxic metals.
I will stick with D
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VP
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trivikram wrote: We have to prove that the production of histindine is inert in nature and its contarsting nature against metals.
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic .
This is a test where the plant produces a chemically inert amino acid which repels the mettalic nature of the soil there by allowing regular plants to grow..Phew...
D it is
We have to strengthen the conclusion
i.e Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils
How is D stating that the high histidine production is the cause of the plant's survival?
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VP
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kripalkavi wrote: trivikram wrote: We have to prove that the production of histindine is inert in nature and its contarsting nature against metals.
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic .
This is a test where the plant produces a chemically inert amino acid which repels the mettalic nature of the soil there by allowing regular plants to grow..Phew...
D it is We have to strengthen the conclusion i.e Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soilsHow is D stating that the high histidine production is the cause of the plant's survival? Kripal: I thought the option D is infact supporting the hypothesis.
HISTIDINE --------> inert to mettalic soil and produced by herb plant which resists the qualities exerted by mettalic soil.
This is proved in the labs so it means the more the herb plans are there in such soild the more is the inertness the soil become and becomes conductive for regular ones.
Option C:
Premise: A certain cultivated herb is one of a group of closely related plants that thrive in soil withhigh concentrations of metals that are toxic to most other plants.
Who knows that 'cos of the proximity of the other plants to this herb plant the other plants are living..We cannot say that the other plants are secreting the H thing. So we can rule out.
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VP
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C doesn't tie these others to the soil or metal at all... how can this be the answer 
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Intern
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I think the answer is D
Histidine = amino acid = makes metals inert
D says that over a period of time the soil that was rich in toxic metal is now suitable for normal plants.....that means that histdine made the metal inert and therefore supports the conclusion
BTW...what the offical answer???
Swagatalakshmi wrote: A certain cultivated herb is one of a group of closely related plants that thrive in soil withhigh concentrations of metals that are toxic to most other plants. Agronomists studyingthe 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, theherb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesisthat would gain support if ______.
A. histidine is found in all parts of the plant—roots, stem, leaves, and flowers
B. the herb’s high level of histidine production is found to be associated with anunusually low level of production of other amino acids
C. others of the closely related group of plants are also found to produce histidine inlarge quantities
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic
E. the concentration of histidine in the growing herb declines as the plant approachesmaturity
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VP
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u2lover wrote: C doesn't tie these others to the soil or metal at all... how can this be the answer Argument says:
A group of plants thrive in metal rich soil.
A herb belonging to this group secretes a large quantity some H-stuff
C says: The others in the group also secrete large quantities of the same H-stuff. So doesn't it suggest that the H-stuff might be responsible for the group's ability to thrive?
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Director
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It's my turn.
I choose D because we want to support the arg that histidine renders the metal inert.
C. others of the closely related group of plants are also found to produce histidine inlarge quantities
Where is the link between other plants and the fact that histidine makes the soil inert?
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic
I'm deeply convinced that it is the right answer, unless there's a trap again. The arg makes the hypothesis that histidine deactivate metals.
So if that's the case, then we can believe that histidine will infiltrate the soil surrounding the plants and clean it. That is best supported by other plants growing, that otherwise wouldn't grow.
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Manager
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I go with C
Swagatalakshmi wrote: A certain cultivated herb is one of a group of closely related plants that thrive in soil withhigh concentrations of metals that are toxic to most other plants. Agronomists studyingthe 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
B. the herb’s high level of histidine production is found to be associated with anunusually low level of production of other amino acids
C. others of the closely related group of plants are also found to produce histidine inlarge quantities
The hypothesis needs to be strengthened. This will happen when other closely related plants also produce histadine in large amounts. In that way we can conclude that it is histadine that helps plants to survive.
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic
If the plant makes the soil inert to toxic metals even then we cannot support that it is histadine that does it. It could be something else that the plants produces and so histadine is not responsible. It does not strengthen the hypothesis.
E. the concentration of histidine in the growing herb declines as the plant approachesmaturity
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Director
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dips wrote: C. others of the closely related group of plants are also found to produce histidine inlarge quantities
The hypothesis needs to be strengthened. This will happen when other closely related plants also produce histadine in large amounts. In that way we can conclude that it is histadine that helps plants to survive.
D. cultivation of the herb in soil with high concentrations of the metals will, over anextended period, make the soil suitable for plants to which the metals are toxic
If the plant makes the soil inert to toxic metals even then we cannot support that it is histadine that does it. It could be something else that the plants produces and so histadine is not responsible. It does not strengthen the hypothesis.
I understand what you mean and actually I am not convinced anymore that D is the best.
But when you say that D doesn't strenghten the hypothesis, I can reply that C neither. Other related plants can produce histidine, but as you said for D(It could be something else that the plants produces and so histadine is not responsible) could be valid for C. We cannot not conclude that histidine is responsible because all the related plants thriving in this kind of soil share the same amino acid. However it supports the argument. And D supports it as well, because it shows that a substance(histidine?) is produced,infiltrates the soil and makes it inert, as does histidine in the lab.
D is maybe too obvious to be the right answer, so C can be the winner...
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Manager
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i got C
whats the OA
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Senior Manager
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I am with C..
D – Cultivation, over an extended period, of this herb will gradually neutralize the toxic metal of the soil. The lab study also demonstrated such outcome.
My wild thought - It might turn out that the herb neutralizes the metal within its body just to clean its food. To do so, probably, it uses a little amount that is enough for its survival. Its cultivation, for en extended period, will eventually clean the whole field is really .......... far reaching conclusion. Given the lab and actual environment is vastly different, it is difficult to believe without any other premise.
C – All the herbs of the group show high H quantity. Definitely, this special feature is needed for thriving in soil with high metal concentration.
I think C has a stronger support ...looking forward for the OA though..
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Senior Manager
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I am with D
Growing the herb makes the metals in the soil inert.
Hence makes the land favorable for other plants
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Senior Manager
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I pick C. If this herb survives because of the large amounts of histidine then the other closely related plants that thrive in the toxic soil could have the same reason.
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Swagatalakshmi wrote: A certain cultivated herb is one of a group of closely related plants that thrive in soil withhigh concentrations of metals that are toxic to most other plants. Agronomists studyingthe 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, theherb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesisthat would gain support if ______.
Fact: HerbA thrive in soil with metals.
Fact: A group of closely related plants thrive in soil with metals.
Fact: HerbA produces histidine, which makes metals harmless to plant.
Hypothesis: Histidine is the reason why HerbA thrive in soil with metals.
If we know that those closely related plants that thrive in metal soil all produce histidine, then we could be reasonably sure that histidine is the reason why they thrive in metal soil.
I would choose C.
I don't think we can necessarily get better soils after planting herbA for some time. The passage didn't talk about where the chemical reaction takes place (inside the plant or in the soil), nor did it talk about whether its effect will last so that it actually changes the soil.
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