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题库 / OG2016-RC-10
Scientists long believed that two nerve clusters in the human hypothalamus, called suprachiasmatic nuclei (SCNs), were what controlled our circadian rhythms. Those rhythms are the biological cycles that recur approximately every 24 hours in synchronization with the cycle of sunlight and darkness caused by Earth's rotation. Studies have demonstrated that in some animals, the SCNs control daily fluctuations in blood pressure, body temperature, activity level, and alertness, as well as the nighttime release of the sleeppromoting agent melatonin. Furthermore, cells in the human retina dedicated to transmitting information about light levels to the SCNs have recently been discovered.
Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. While scientists do not dispute the role of the SCNs in controlling core functions such as the regulation of body temperature and blood pressure, scientists now believe that circadian clocks in other organs and tissues may respond to external cues other than light—including temperature changes—that recur regularly every 24 hours.
The author of the passage would probably agree with which of the following statements about the SCNs?
The SCNs are found in other organs and tissues of the body besides the hypothalamus.
The SCNs play a critical but not exclusive role in regulating circadian rhythms.
The SCNs control clock genes in a number of tissues and organs throughout the body.
The SCNs are a less significant factor in regulating blood pressure than scientists once believed.
The SCNs are less strongly affected by changes in light levels than they are by other external cues.
题目分析：
文章推断题：作者可能同意以下哪个关于SCNs的观点？
这道题看一遍会发现有的选项把文章中的一些点混在一起，比如A里面在其他地方发现的是genes而不是SCNs，误以为有原文可以对应的部分。但正确选项是需要搞清作者的意图，总结出来——SCNs不是唯一可以控制CR的，但不可否认它的重要性
选项分析：
A选项： 除了下丘脑，在其它器官、组织也发现了SCNs: 文章一开始提到了在下丘脑发现SCNs，但没有提到是否其它地方有。
B选项：正确。SCNs在控制生物周期上起到关键但不是绝对作用：和文章叙述脉络一致——从认为SCNs独自调控到发现还有别的genes和SCNs一起调控。
C选项：SCNs控制身体中许多器官的生物钟：文章中的小白鼠实验证明了有些器官不受SCNs控制。
D选项：SCNs在调控血压方面没科学家想的那么重要：文章第二段提到“科学家不否认SCNs在调控血压方面的作用”。
E选项：光线变化没有外部因素对SCNs影响大：文章说的是SCNs受光线影响，其他组织的生物钟可能受外部因素影响；未将二者比较。
B选项：正确。SCNs在控制生物周期上起到关键但不是绝对作用：和文章叙述脉络一致——从认为SCNs独自调控到发现还有别的genes和SCNs一起调控。
C选项：SCNs控制身体中许多器官的生物钟：文章中的小白鼠实验证明了有些器官不受SCNs控制。
c选项定位：Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. 四个控制昼夜周期的关键基因被发现活跃在每一个组织中，然而，不仅仅是在苍蝇，老鼠和人类SCN中。此外，当通常随意进食的实验室大鼠每天被喂食一次时，肝脏中时钟基因的峰值活性移动了12小时，而SCNS中相同的时钟基因则与光周期保持同步。
这就说明scn并没有控制许多组织和器官的时钟基因，它可能只能保证控制它其中的时钟基因。
c选项定位：Four critical genes governing circadian cycles have been found to be active in every tissue, however, not just the SCNs, of flies, mice, and humans. In addition, when laboratory rats that usually ate at will were fed only once a day, peak activity of a clock gene in their livers shifted by 12 hours, whereas the same clock gene in the SCNs remained synchronized with light cycles. 四个控制昼夜周期的关键基因被发现活跃在每一个组织中，然而，不仅仅是在苍蝇，老鼠和人类SCN中。此外，当通常随意进食的实验室大鼠每天被喂食一次时，肝脏中时钟基因的峰值活性移动了12小时，而SCNS中相同的时钟基因则与光周期保持同步。
这就说明scn并没有控制许多组织和器官的时钟基因，它可能只能保证控制它其中的时钟基因。
e选项说的是这个scn受其他外部因素影响比受光线影响因素要多，这是错误的。因为是scn和其他外部因素影响生物周期，而不是SCN被影响。
rc
审题非常重要The author of the passage would probably agree with
作者同意的地方肯定在第二段，因为整体是质疑的态度，第二段才出现正确的观点，快速定位，需要认真审题；刚看到题就想去乱找scn所有东西，是错的，浪费很多时间
不太明白为什么c错了。。。
为什么选B呢
B 来自最后一段的 While scientists do not dispute the role of the SCNs in controlling core functions， scientists now believe that circadian clocks in other organs and tissues may respond to external cues other than light。——主结论
不太对吧这个推理...最后一段的这句话没有说到SCNs是否唯一啊。。。
说的有道理，同意+1
SCNs应该是起到决定性作用的，不需要说明唯一性
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Furthermore, cells in the human retina dedicated to transmitting information about light levels to the SCNs have recently been discovered.
细节2，联系上下文，需自己总结推理