推 wixter : 謝謝老師 好險在睡前等到這篇文章:) 05/20 02:39
原文與題目：
This tunneling phenomenon at very low temperatures suggested
my hypothesis about a cold prehistory of life: the formation
of rather complex organic molecules in the deep cold of
outer space, where temperatures usually reach only a few
degrees Kelvin. Cosmic rays (high-energy protons and other
particles) might trigger the synthesis of simple molecules,
such as interstellar formaldehyde, in dark clouds of
interstellar dust. Afterward complex organic molecules would
be formed, slowly but surely, by means of tunneling. After I
offered my hypothesis, Hoyle and Wickramasinghe argued that
molecules of interstellar formaldehyde have indeed evolved
into stable polysaccharides such as cellulose and starch.
Their conclusions, although strongly disputed, have
generated excitement among investigators such as myself who
are proposing that the galactic clouds are the places where
the prebiological evolution of compounds necessary to life
occurred.
The author's hypothesis concerning the cold prehistory of
life would be most weakened if which of the following were
true?
(A) Cosmic rays are unlikely to trigger the formation of
simple molecules.
(B) Tunneling occurs only in a narrow band of temperatures
around zero degrees Kelvin.
(C) The synthesis of interstellar formaldehyde can be
activated by means other than cosmic rays.
(D) Simple molecules can be synthesized by means of
tunneling.
(E) Classical chemical reactions do not occur at
temperatures close to absolute zero.
題目問：下方何者最能推翻作者所提的 cold prehistory of life？
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cold prehistory of life 的示意圖：
步驟一 步驟二
tunneling
Cosmic rays -> simple molecules ---------> complex molecules
(例如 甲醛)
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答案分析：
答案
(A) Cosmic rays are unlikely to trigger the formation of
simple molecules.
(A) 宇宙射線不可能引發形成簡單分子
也就是說示意圖中的步驟一根本不會發生，那當然就沒有步驟二了，
因此 life 要從何而來？所以如果 (A) 成立，那麼 cold
prehistory 就被推翻了。
答案
(C) The synthesis of interstellar formaldehyde can be
activated by means other than cosmic rays.
(C) 甲醛的合成是經由別的管道，並非由宇宙射線所引發
如此一來，乃示意圖中的步驟一，並非由宇宙射線開始，而是其他原
因。但是甲醛確定會產生，因此可以據以進行步驟二的 tunneling，
而繼續生成複雜分子。
所以 cold prehistory 仍然有可能成立，只是原理論要稍微修正一
下而已。
結論：答案 (A) 比 (C) 更能合理推翻 cold prehistory of life
------------------------------------------------------------
wixter (原 po) 提問：
但我覺得 formation 跟 synthesis 並不等價，formation 指的是
形成 simple molecule 而 synthesis 指的是 simple molecules
互相結合後，生成的混合物。
答：我們可以從兩個方面來說明這個問題。
一、根據原文用語：
原文用 formation 與 synthesis 分別如下：
a cold prehistory of life: the formation of rather complex
organic molecules in the deep cold of outer space, where
temperatures usually reach only a few degrees Kelvin. Cosmic
rays (high-energy protons and other particles) might trigger
the synthesis of simple molecules,
所以 formation, synthesis 與 simple, complex 的搭配與 Wixter
所提的想法正相反。
這裡我想要特別跟考生說，看任何 GRE 的題目，都要以原題的文字
為準，不要以自己的專業知識，或是感覺而任意更動內容。
二、根據字典定義，systhesis 與 formation 有差別嗎？
根據美國傳統字典 American Heritage Dictionary 4th Ed.
(En-En) 的解釋：
synthesis:
Chemistry. Formation of a compound from simpler compounds or
elements.
也就是說，這兩個字在化學反應中的用法，並沒有差別。
當然，或許在化學專業領域中這兩個字有所不同，不過在考 GRE 的
時候，這些差異並不會列入考慮。
結論：在本題中，formation 與 synthesis 這兩個字可以互換使用
，不必過慮。
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以上提供給各位做個參考。
謝忠理 xiezl.info@gmail.com
http://oketw.blogspot.tw
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