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题库 / Prep2007E2-RC-15
Solar ponds are bodies of water in which circulation is incomplete and there is a very high salt concentration that increases with depth. This vertical change in salinity serves to trap heat because concentrated brine in the lowest water level acts as a collector and storage area for solar heat, while the less saline, lighter water at the upper levels provides insulation. Heat is thus retained in the depths.
An artificial pond of this type has been constructed on the western shore of the Dead Sea in Israel in order to test its suitability as a source of low-grade heat for conversion into electricity. An immediate threat to the success of the venture was the growth of algae. Water in solar ponds must be kept maximally transparent to allow penetration of light to the deep storage area. Therefore, any particles of matter in the water, such as algae cells, that scatter or absorb light will interfere with the collection of heat.
One proposed method of controlling the algae was the application of an algicide. However, the Dead Sea is a closed body of water without any outlet and as such is very easily contaminated. Extensive use of chemicals in numerous future full-scale solar ponds would lead to such contamination of the Dead Sea, which now enjoys a lucrative tourist trade.
A recent experiment has supplied a more promising method for controlling the algae. To repress the algae cells' capacity for accommodating themselves to environmental changes, the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water. This shock reduced the cells' ability to regulate the movement of water through their membranes. They rapidly absorbed water, resulting in distortions of shape, increase in volume, and impairment to motility. Their buoyancy adversely affected, the cells sank to the bottom of the pond, where they encountered the hot waters of the storage layer and were destroyed. This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use.
Which of the following, if true, would seriously undermine the validity of the conclusions drawn from the experiment described in the last paragraph of the passage?
The algae cells that sank to the bottom of the pond were destroyed only after a time lag of twenty-four hours.
The lateral motility of the algae cells that sank to the bottom of the pond was not impaired.
The water with which the artificial solar pond was diluted contained microorganisms that kill algae.
The algae cells that sank to the bottom of the pond were actually killed by the rapid change in pressure.
The higher salinity brought about through evaporation increased the transparency of the upper levels of water in the pond.
题目分析：
题目释义：
细节题目
考点：
逻辑结构（Logical structure）
旨在考察我们对文章结构的认知，以及对作者行文目的的判断。
我们首先要找到最后一段那个实验作者的结论是什么，是“This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use”这个论点可供攻击的点是“清洁”和“有效”。注意题目问的是削弱。
选项分析：
A选项：沉入底部的藻类细胞只有经过24小时后才能被破坏。从“有效”方面攻击。但是24小时这个时间并不影响这个方法的有效性。
B选项：沉入底部的藻类细胞只有经过24小时后才能被破坏。从“有效”方面攻击。但是24小时这个时间并不影响这个方法的有效性。
C选项：Correct. 稀释人工太阳能池的水中含有杀死水藻的微生物。两方面攻击，“清洁”方面有微生物不知道是否能保持死海的清洁。“有效”方面我们无从得知究竟是作者说的原因还是这些微生物杀死了藻类细胞。
D选项：沉入底部的藻类细胞其实是被骤变的压力所杀死的。这个选项较易误选。注意这个选项并不能严重的削弱作者的结论。作者的结论是有效的杀死和清洁。该选项不反驳其中任何一点，只是作者说的消灭机理有问题。
E选项：更高的盐度带来通过蒸发引起的上层水的透明度上升。该选项和作者的结论无关。
C. 人工太阳能池被稀释的水中含有杀死藻类的微生物。正确 原文提到藻类细胞是在底部遇热死亡的，沉淀在底部，换言之，藻类细胞需要活着才能吸水，下沉到底部，死亡。 而微生物杀死了藻类的话，水藻就无法下沉，挡住了阳光的吸收，干扰了太阳池的使用。
B选项lateral motility横向移动，横向移动是否受损无所谓登录 或 注册 后可以参加讨论
题目要削弱，“加盐再注水”这个方法→能让水藻不浮在水面之间的因果联系
方案目的：Water in solar ponds must be kept maximally transparent to allow penetration of light to the deep storage area.
方案：To repress the algae cells' capacity for accommodating themselves to environmental changes, the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water.
C人工太阳能池被稀释的水中含有杀死藻类的微生物。 正确 原文提到藻类是在底部遇热死亡的，沉淀在底部，换言之，藻类需要活着才能吸水，下沉到底部，死亡。 而微生物杀死了藻类的话，水藻就无法下沉，挡住了阳光的吸收，干扰了太阳池的使用。-方案可行性
选项B：The lateral motility of the algae cells that sank to the bottom of the pond was not impaired.
沉到水底的侧面细胞是否能动性受限对方案没有影响，因为已经沉到水底了
B沉到池塘底部的藻类细胞的横向运动没有受到影响。 无关 方法能让藻类细胞沉到低，杀死藻类就行
C人工太阳能池被稀释的水中含有杀死藻类的微生物。 正确 原文提到藻类是在底部遇热死亡的，沉淀在底部，换言之，藻类需要活着才能吸水，下沉。 而微生物杀死了藻类的话，水藻就无法下沉，挡住了阳光的吸收，干扰了太阳池的使用。
water...可杀死algae，就不会之后一系列：They rapidly absorbed water, resulting in distortions of shape, increase in volume, and impairment to motility. 下沉了
motility：运动性，移动性
【思路点拨】
定位最后一段
这种方法可以有效地控制有害藻类，同时使太阳能池成为最清洁的技术之一，为人类提供能源。
任何能让降低这个方法有效性的因素，都能削弱该结论。
A 沉入池塘底部的藻类细胞在24小时后才被破坏。 无关 方法能让藻类细胞沉到低，杀死藻类就行
B沉到池塘底部的藻类细胞的横向运动没有受到影响。 无关 方法能让藻类细胞沉到低，杀死藻类就行
C人工太阳能池被稀释的水中含有杀死藻类的微生物。 正确 原文提到藻类是在底部遇热死亡的，沉淀在底部，换言之，藻类需要活着才能吸水，下沉。 而微生物杀死了藻类的话，水藻就无法下沉，挡住了阳光的吸收，干扰了太阳池的使用。
D 下沉到池塘底部的藻类细胞实际上是被迅速变化压力杀死的。无关 方法能让藻类细胞沉到低，杀死藻类就行
E 通过蒸发带来的高盐度增加了池塘上层水的透明度。无关
优秀的解释！登录 或 注册 后可以参加讨论
b活性没有消失，似乎也是削弱 （保留）
c 坑爹的虽然杀了讨厌的藻类，但是又把微生物加进来了，前文提到微生物也会阻止阳光热量透入，典型拆了东墙补西墙，严重削弱。
d管它怎么死 ，反正死了就行。
e上曾水那是越透明越好啊，加强方法。
综上所述，选c 呀。 这道题选b 的，就是没仔细看c
同选B，我是这样说服自己的。这个方法的是用加盐的密度，导致一系列海藻的物理反应（形状变形absorbed water, resulting in distortions of shape, 体积增大increase in volume, and丧失了运动能力 impairment to motility）---最后使其浮力产生变化，让他沉入了海底被烫死。我认为最重要的过程是盐增多了---浮力产生了变化，其中形状变形、体积增大、运动能力减少是并列的3个可以盐的含量改变浮力的表现。而B中只说了，运动能力不会受损，但盐多了还是会变形和变大，浮力还是会改变。（所以这个逻辑链没有gap，科学真理，盐含量大了就会改变浮力，削弱其中的一个现象很无力）其次，如果说这个反应的机理仅仅是因为引入了海水里的细菌把海藻给杀死了，那么我们可以认为这个方法是无效的（虽然2者同时达到了目的，但第一种方法达到目的 的本质上因为“细菌杀死海藻“”这种其他方法让它达到的目的）。举个例子，我吃很多馒头和一点肉增肥。其实是因为我吃肉增肥的，跟馒头半毛钱关系都没有，所以我说吃馒头使我增肥无效。
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唯一的点在于微生物是不是又引入了其他不清洁的 any particles of matter in the water, such as algae cells, that scatter or absorb light will interfere with the collection of heat.