2772大全Passage 14 跪求高人解释

mingmings

Passage 14 (14/63)Nearly a century ago, biologists found that if they separated an invertebrate animal embryo into two parts at an early stage of its life, it would survive and develop as two normal embryos. This led them to believe that the cells in the early embryo are undetermined in the sense that each cell has the potential to develop in a variety of different ways. Later biologists found that the situation was not so simple. It matters in which plane the embryo is cut. If it is cut in a plane different from the one used by the early investigators, it will not form two whole embryos.
A debate arose over what exactly was happening. Which embryo cells are determined, just when do they become irreversibly committed to their fates, and what are the “morphogenetic determinants” that tell a cell what to become? But the debate could not be resolved because no one was able to ask the crucial questions in a form in which they could be pursued productively. Recent discoveries in molecular biology, however, have opened up prospects for a resolution of the debate. Now investigators think they know at least some of the molecules that act as morphogenetic determinants in early development. They have been able to show that, in a sense, cell determination begins even before an egg is fertilized.
Studying sea urchins (any of numerous echinoderms (class Echinoidea) that are usually enclosed in thin brittle globular tests covered with movable spines海胆), biologist Paul Gross found that an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm of the egg cell; i.e., in that part of the cell’s protoplasm that lies outside of the nucleus. In the unfertilized egg, the substances are inactive and are not distributed homogeneously. When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with. Since the substances are unevenly distributed in the egg, when the fertilized egg divides, the resulting cells are different from the start and so can be qualitatively different in their own gene activity.
The substances that Gross studied are maternal messenger RNA’s—products of certain of the maternal genes. He and other biologists studying a wide variety of organisms have found that these particular RNA’s direct, in large part, the synthesis of histones, a class of proteins that bind to DNA. Once synthesized, the histones move into the cell nucleus, where section of DNA wrap around them to form a structure that resembles beads, or knots, on a string. The beads are DNA segments wrapped around the histones; the string is the intervening DNA. And it is the structure of these beaded DNA strings that guide the fate of the cells in which they are located.

5.It can be inferred from the passage that the initial production of histones after an egg is fertilized takes place
(A) in the cytoplasm
(B) in the maternal genes
(C) throughout the protoplasm
(D) in the beaded portions of the DNA strings（A）

(E) in certain sections of the cell nucleus
6.It can be inferred from the passage that which of the following is dependent on the fertilization of an egg?
(A) Copying of maternal genes to produce maternal messenger RNA’s
(B) Synthesis of proteins called histones
(C) Division of a cell into its nucleus and the cytoplasm
(D) Determination of the egg cell’s potential for division（B）

(E) Generation of all of a cell’s morphogenetic determinants
9.Which of the following circumstances is most comparable to the impasse biologists encountered in trying to resolve the debate about cell determination (lines 12-18)?
(A) The problems faced by a literary scholar who wishes to use original source materials that are written in an unfamiliar foreign language
(B) The situation of a mathematician who in preparing a proof of a theorem for publication detects a reasoning error in the proof
(C) The difficulties of a space engineer who has to design equipment to function in an environment in which it cannot first be tested
(D) The predicament of a linguist trying to develop a theory of language acquisition when knowledge of the structure of language itself is rudimentary at best（D）

(E) The dilemma confronting a foundation when the funds available to it are sufficient to support one of two equally deserving scientific projects but not both

这三题我看了20分钟还是没有什么想法？大家摘着会的给我解释解释，谢谢！

5.It can be inferred from the passage that the initial production of histones after an egg is fertilized takes place
(A) in the cytoplasm
(B) in the maternal genes
(C) throughout the protoplasm
(D) in the beaded portions of the DNA strings（A）

(E) in certain sections of the cell nucleus
6.It can be inferred from the passage that which of the following is dependent on the fertilization of an egg?
(A) Copying of maternal genes to produce maternal messenger RNA’s
(B) Synthesis of proteins called histones
(C) Division of a cell into its nucleus and the cytoplasm
(D) Determination of the egg cell’s potential for division（B）

(E) Generation of all of a cell’s morphogenetic determinants
9.Which of the following circumstances is most comparable to the impasse biologists encountered in trying to resolve the debate about cell determination (lines 12-18)?
(A) The problems faced by a literary scholar who wishes to use original source materials that are written in an unfamiliar foreign language
(B) The situation of a mathematician who in preparing a proof of a theorem for publication detects a reasoning error in the proof
(C) The difficulties of a space engineer who has to design equipment to function in an environment in which it cannot first be tested
(D) The predicament of a linguist trying to develop a theory of language acquisition when knowledge of the structure of language itself is rudimentary at best（D）

(E) The dilemma confronting a foundation when the funds available to it are sufficient to support one of two equally deserving scientific projects but not both

这三题我看了20分钟还是没有什么想法？大家摘着会的给我解释解释，谢谢！

nancy5130

5.原文第三段－Once synthesized, the histones move into the cell nucleus, 前一句－these particular RNA’s direct the synthesis of H,而第二段种说了这个RNA就是located in the cytoplasm of the egg cell说明开始的发生地是C...., 从另一个角度讲， 说了是move into the cell nucleus, 说明了开始是在nucleus的外面，第二段说了那个C...就是在nucleus的外面。

6.我是用的排除法 A－全文没有提到copying  B－感觉有点对，尤其从前一个题分析能得出类似得结论  C－ 全文没有说把cell分成里外两部分 D－后两段说得是受精以后，但没有涉及到potential for division E－文章也没有提到

9. 我得理解是争论没有解决是因为没有人能够有能力提出一个能让人有所作为的问题，只有对这个领域不了解才可能导致没法提出建设性的问题。那么看了半天，只有D还顺眼点。

不知道我理解的对不对

maxwhite

这篇看了好久还是错了一半T T

9、But the debate could not be resolved because no one was able to ask the crucial questions in a form in which they could be pursued productively 像楼上说的，定位貌似在这里。

原文：因为没有涉及到crucial quetion所以没有productivity----因为没有办法test仪器所以不能投入使用。

Cherliuiking

这道做的时候， 还行， 回头再细看时， 却发现还是挺复杂的
杨继－阅读精解是这么解释的
9. 类比题， 先总结原文。 此问题无法解决， 因为没有人能将此问题表述为一个可以继续进行有效研究的方式， 即没有任何途径能将此研究进行下去， 其原因是当时生物学家的认识有限。

D.  一个试图研究语言习得理论（语言学一个分支）的语言学家， 其本向关于语言结构的知识也就是初级水平（rudimentary at best）

reirayanqing

Q5,6 看三、四paragraph together

biologist Paul Gross found that an unfertilized egg contains substances that function as morphogenetic determinants. They are located in the cytoplasm(Q5） the egg cell; i.e., in that part of the cell’s protoplasm that lies outside of the nucleus.In the unfertilized egg, the substances are inactive and are not distributed homogeneously. When the egg is fertilized, he substances become active and, presumably, govern the behavior of the genes they interact with.Since the substances are unevenly distributed in the egg, when the fertilized egg divides, the resulting cells are different from the start and so be qualitatively different in their own gene activity.
The substances that Gross studied are maternal messenger RNA’ － sproducts of certain of the maternal genes. He and other biologists studying a wide variety of organisms have found thatthese particular RNA’s direct, in large part, the synthesis of histones, a class of proteins that bind to DNA(Q6). Once synthesized, the histones move into the cell nucleus, where section of DNA wrap around them to form a structure that resembles beads, or knots, on a string. The beads are DNA segments wrapped around the histones; the string is the intervening DNA. And it is the structure of these beaded DNA strings that guide the fate of the cells in which they are located.

reirayanqing

Q5 : substance作为  morphogenetic determinants （存在于Cytoplasm）
       substance 就是 maternal messenger RNA’
所以 maternal messenger RNA’  即是 morphogenetic determinants 也就存在于Cytoplasm

chaos1026

弱弱的表示看了好久第9题, 结果发现把题目看错了.

是问以下哪种情况, 跟那些生物学家在解决debate时遇到的困难是类似的

然后就如3L所说,
no one was able to ask the crucial questions in a form in which they could be pursued productively. (没人能提出一些关键性的问题, 并且这些问题是要以一种能够pursued productively).

连关键性的问题都提出不了, 更别说解决了. 为什么会这样? 是不是因为基础知识不牢固?

是不是就跟D一样, 一个试图研究某种语言理论学家, 他本身对语言结构的认识也就是初级水平, 那还谈什么研究出某种语言理论.