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Thread: A certain cultivated herb

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    A certain cultivated herb

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    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
    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
    C. others of the closely related group of plants are also found to produce histidine in
    large quantities
    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
    E. the concentration of histidine in the growing herb declines as the plant approaches
    maturity


    OA is
    SPOILER: E



    PLease explain

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    Good question. This is a tough one. It was a very close call between D and E, and I choose E.

    In questions like these, where causality is involved, in order to strengthen the argument, we need to prove that the result is ONLY obtained as a consequence of what was stated.

    For ex: If A causes B, then

    - if we say no other C causes B, then we are strengthening the argument.

    - similarly, if we say some other C causes B, then we are weakening the argument.

    In this question

    A = high histidine

    B = nullify metallic affect

    Since we need to strengthen here, we need to find out an answer which states (directly or indirectly) that metallic affect was indeed nullified by histidine ONLY

    A. histidine is found in all parts of the plant—roots, stem, leaves, and flowers

    Not a great strengthener. Moreover histidine present in other parts of the herb is not relevant. Only which is present in roots is relevant

    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

    This is actually a weakener, because it implies that there is another source which could be possible for nullifying metallic affect

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

    OOS

    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

    This is actually a weakener. It says that over time, the soil itself adjusts itself to the plant, indicating that the soil is the one nullifying the metallic affect, and not the plant.

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

    Yes, strengthens the argument. It implies that the plant has been producing histidine for a long time, to nullify the metallic affect, and hence as the plant reaches maturity, the plant's production of histidine has decreased.

    If histidine weren't the cause for nullifying metallic affect, the plant would still be capable of producing large amount of histidine even when it is mature

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    Quote Originally Posted by sparsh.21 View Post
    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
    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
    C. others of the closely related group of plants are also found to produce histidine in
    large quantities
    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
    E. the concentration of histidine in the growing herb declines as the plant approaches
    maturity
    PLease explain

    The key is in the question itself..

    "the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if"


    The hypothesis is in bold-faced text above... if it allows it to grow, then it is also the reason for its saturation (maturity, death if i should say), in growth.. E states that precisely!

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    Quote Originally Posted by skale View Post
    The key is in the question itself..

    death if i should say
    death is an extreme, but sort of no-more-growth stage..

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    again from E we can infere that as the herb matures (due to some other reason, not necessarily because of low histidine production), it starts producing lesser amount of histidine. In such case low histidine production is an outcome of herbs maturity. If we infere this way then no way we can say that histidine is crucial.
    So i find E to be ambiguous.

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    An Urch Guru Pundit Swami Sage
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    E becasue the hinestine will get consumed and hence its concentration would decrease.

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    D is most suitable.

    How can E support the logic?

    How are we assuming that the production of histidine decreses with maturity?Is it mentioned anywhere?
    The only thing mentioned is histidine nullifies the effect of toxic metals and this is best supported by D.

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    An Urch Guru Pundit Swami Sage cartera's Avatar
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    OA is wrong, in my version of OA it is C and C makes more sense because the 1st sentece says: 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.

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    An Urch Guru Pundit Swami Sage genius_in_the_gene's Avatar
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    Don't think it can be E. Why would the plant exhaust its amino acids? And above all its out of scope. I would go with D.

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    A. Doesn't matter where the amino acid is present or produced.
    B. May be decline in other amino acids can allow the herb to grow. This actually weakens.
    D. This in fact helps the herb to adapt and thus no need of amino acid.

    E. After some time the metals become inert because of excessive amino acid. Once metal becomes inert then no further need of amino acid. This strengthens.
    C. This tells that others too grow because of high amino acid production and this strengthens in a better way.

    I will go with C. E, though strengthens, but raises a lot of questions.

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