132. According to the passage, which of the following best describes a function performed by oligosaccharins? (A) Regulating the daily functioning of a plant’s cells (B) Interacting with one another to produce different chemicals (C) Releasing specific chemical messengers from a plant’s cell walls (D) roducing the hormones that cause plant cells to differentiate to perform different functions (E) Influencing the development of a plant’s cells by controlling the expression of the cells’ genes Supporting ideas To answer this question, look for information that is provided in the passage. Oligosaccharins are regulatory molecules (line 13). they form part of the complex system that turns on, or expresses, a small subset of genes in a particular kind of cell. As explained in the first paragraph, this process allows plant cells to differentiate and form different plant structures. Unlike the five major plant hormones, the oligosaccharins affect a specific aspect of the plant’s growth (lines 14–17). A ~e passage does not discuss the daily functioning of a plant’s cells. B ~e passage provides no evidence of this interaction. C ~e oligosaccharins are fragments of the cel wal (line 39) and the specific chemical messengers from the cel wal (lines 43–44). D ~e oligosaccharins are not said to produce hormones. E Correct. Oligosaccharins are part of the system that turns on, or expresses, the subset of a cell’s genes that allows cells to grow into different plant structures. ~e correct answer is E.
我了解文章的大意，五种hormones 和 另外一个叫 Oligosaccharins 的分子作比较。反正说五种hormones是多功能的，而Oli是specific 的。其他就没看出来还有什么功能。 另外文章开头几句话有点不明白，有个版本的解释说， The answer is that only a small subset of the genes in a particular kind of cell are expressed, or turned on, at a given time 是主旨句，全文讨论的中心，可知文章应为结论解释型。我没看出来这句话和五种hormones 和 Oli 的分子有什么关系啊
对于这题OG中的官方解释我也没看懂they form part of the complex system that turns on, or expresses, a small subset of genes in a particular kind of cell. As explained in the first paragraph, this process allows plant cells to differentiate and form different plant structures.这句话难道是说Oli的功能的吗？
我今天也在总结这一篇~ 第一段确实是总领，告诉了你为什么要讨论5 hormones和O——第一句先说了一个现象（all the cells...same completement of genes），第二句用问句点出了和现象矛盾的另一个现象（same genes but different structures），紧接着这句全文的TS就告诉我们，这是因为有a system of chemical messenger来控制同一套genes的不同表达，然后说这套chemical messengers包括了5 hormones和O，后面全文就是展开描述这两种chemical messengers各自控制expression of genes的不同机制（包括在植物的和在动物上的）
我今天刚看了这篇文章，你仔细看一下Line5-9，是说细胞中只有一部分基因被表达出来，这个过程中涉及到hormones and other regulatory molecules. Line13,regulatory molecules called oligosaccharins.所以选E，这是我的个人理解，希望对你有所帮助！
How then can these cells differentiate and form structures as different as roots, stems, leaves, and fruits? The answer is that only a small subset of the genes in a particular kind of cell are expressed, or turned on, at a given time. This is accomplished by a complex system of chemical messengers that in plants include hormones and other regulatory molecules.大概翻译一下，可能不太准确，帮助你理解哈：这些细胞是怎样分裂形成不同的结构，如根茎叶花？答案是仅仅有基因中的一小部分在一个特殊的细胞中在一个特定的时间被表达出来。这个过程是有一系列复杂的化学信号完成的，这些化学信号包括荷尔蒙和其他一些调节分子。而这里面得调节分子就是oli，和选项e里的Influencing the development of a plant’s cells by controlling the expression of the cells’ genes意思一致。
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发表于 2011-5-6 04:12:45
roducing the hormones that cause plant cells to differentiate to perform different functions
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