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标题: 【请教】关于Lyme Disease的问题 [打印本页]

作者: 晓野的野 时间: 2013-3-8 21:24
标题: 【请教】关于Lyme Disease的问题
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

A Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice

B Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on

C Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice

D Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed

E Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans

答案是B

可是感觉很疑惑，原文说更多的幼虫会吃没有感染的hosts，所以tricks感染病毒的数量会减少。

这个好像和deer trick 的population的size没啥关系吧。
感觉D选项更加合适一点呢....

什么意思啊?
请各位NN过来指教一下~~

作者: 晓野的野 时间: 2013-4-7 15:36
自己顶一个自己的今天又看到一道这个的变体题简直无法直视囧rz

Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium and hence the number of people contracting Lyme disease would likely decline.
Which of the following, if true, most strengthens the argument?

A. Ticks do not suffer any adverse consequences from carrying the bacterium that causes Lyme disease in humans.
B. There are no known cases of a human’s contracting Lyme disease through contact with white-footed mice.
C. A deer tick feeds only once while in the larval stage.
D. A single host animal can be the source of bacterium for many tick larvae.
E. None of the other species on which deer tick larvae feed harbor other bacteria that ticks transmit to humans

作者: waihou32 时间: 2013-5-2 22:38
十分不解啊！！！同问啊！！！！

作者: waihou32 时间: 2013-5-2 22:46
我的理解是如果deer tick的数量不会被available feed所限制,那么这些tick根本就不会在乎对食物的选择,也就是说,即使uninfected hosts增多了这些ticks也不一定增加对uninfected的食入量,因为它们的population size(对个体来说就是其存亡)并不会受到威胁；这应该就切断了原文的逻辑,从而导致结论没有依据；

作者: naryi 时间: 2013-5-7 19:20
如果deer tick的数量大小被其幼虫阶段所能吃的食物的可得性所限制即它幼时能吃的不够那它就顾不了那么多，也会吃也会吃感染的白老鼠这样的话得到细菌的tick数量便不会减少还求NN透彻分析啊～～

作者: guaiss 时间: 2013-6-29 22:42
我的理解是这样的
If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts，so the number of ticks acquiring the bacterium would likely decline.
这句话的一个必要条件是 deer tick 的总量没有变多
总量 = 吃不带细菌的宿主的 + 吃带细菌的宿主的
如果deer tick的总量变多的的话吃不带细菌的宿主的tick变多吃带细菌的宿主的tick有可能也变多了使得结论不成立
B选项描述了deer tick 总量有可能变多的一个因素

作者: leeng 时间: 2013-9-7 16:58
楼上强悍！赞一个！

作者: hu00033 时间: 2013-10-30 21:39

guaiss 发表于 2013-6-29 22:42
我的理解是这样的
If the population of these other species were increased, more of the larvae would b ...

厉害，看了你的解释瞬间懂了

作者: 奔奔宝贝 时间: 2014-3-20 21:20

guaiss 发表于 2013-6-29 22:42
我的理解是这样的
If the population of these other species were increased, more of the larvae would b ...

能再分析一下D选项吗? 我觉得D选项属于干扰因素。

作者: september918 时间: 2015-8-8 18:09

guaiss 发表于 2013-6-29 22:42
我的理解是这样的
If the population of these other species were increased, more of the larvae would b ...

看一下！

作者: Daeny 时间: 2016-6-24 17:42
看一下！

作者: itssuperoli 时间: 2016-9-9 04:49
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.
Which of the following would it be most important to ascertain in evaluating the argument? 目的：找到gap。评价题
背景：lyme disease 是由deer ticks体内的细菌引起的。Deer tick是在幼虫时期因为寄生在感染的白脚鼠所以才有体内的细菌。那些寄生在未感染物种的tick在幼虫时期没有染上这个细菌。
dt总量 =  吃不带细菌的宿主的dt的比例＊dt总量 + 吃带细菌的宿主的的比例＊dt总量
题目的逻辑链：提高不带细菌的宿主的数量－更多的dt选择寄生在这些不带细菌的宿主身上－携带细菌的dt数量下降
gap：吃不带细菌的宿主的dt的比例上升  吃带细菌的宿主的的数量下降成立吗？需要dt总量不变才成立。
A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice
其他物种和白脚鼠之间的信息，无关。杀。
B. Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on
是否dt的总数能被扁虱幼虫时期寄生对象的可得性限制住。即dt总量保持不变。这个复合猜想的gap，成立。
C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice
是否感染的扁虱的数量能被逐渐增多的捕食白脚鼠的物种数量控制。？？？为什么不对？
题目里问的是infected dt 的数量能否从m途径改变；c选项说的是n途径能改变infected dt的数量。N途径对m途径无影响。杀
（e.g. 做出租车会迟到吗？ C说啊哈做地铁不会迟到哦。这事两个手段，干扰项。不能选）
D. Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed
是否那些幼虫时期没有感染的扁虱成年后会被感染，因为它们吃了那些感染的扁虱接触过的鹿，会变异成感染的扁虱。这个现象在人为提高不带细菌的宿主之前之后都是静态不变的。纵然确实会使扁虱变异，之前这种现象也是存在的。所以无所谓。杀
E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans
其他细菌，无关。杀

终于想通了，希望能帮助到你们！

作者: 阿霖 时间: 2016-9-11 10:19
说一下我个人的看法，欢迎大家探讨。
这道题目的核心其实就是GMAT里面经常考到的一个点：百分比不等于实际数（percentage不等于number）
把整个ticks群体想象成一个圆，这个圆里面一部分以含细菌的生物为食（part A），另外一部分以不含细菌的生物为食（part B）。不含细菌的生物增加，会使得这个圆的比例划分出现改变：part A减少，part B增加，从而ticks中感染疾病的比率减少。但结论却是不感染疾病的ticks的实际数量减少。因此本题evaluate的关键点在于ticks的总量（即圆的大小）是否会改变。

作者: 阿霖 时间: 2016-9-11 10:28

itssuperoli 发表于 2016-9-9 04:49
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pic ...

对D选项的分析非常好，这道题目的结论是一个动态的变化，因此不能用一个前后一样的静态现象去evaluate一个动态现象。

作者: itssuperoli 时间: 2016-9-11 20:05

阿霖发表于 2016-9-11 10:28
对D选项的分析非常好，这道题目的结论是一个动态的变化，因此不能用一个前后一样的静态现象去evaluate一 ...

谢谢，我也是最近发现好些逻辑题都可以从静态变化还是动态变化这个角度去排除选项。交流分享～加油！！！

作者: 阿霖 时间: 2016-9-12 16:57

itssuperoli 发表于 2016-9-11 20:05
谢谢，我也是最近发现好些逻辑题都可以从静态变化还是动态变化这个角度去排除选项。交流分享～加油！！！ ...

嗯哪，加油~~

作者: CXY1029 时间: 2016-9-23 17:05

itssuperoli 发表于 2016-9-9 04:49
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pic ...

Mark一下！

作者: CXY1029 时间: 2016-9-23 17:05

阿霖发表于 2016-9-11 10:19
说一下我个人的看法，欢迎大家探讨。
这道题目的核心其实就是GMAT里面经常考到的一个点：百分比不等于实际 ...

同意！

作者: Kirskey 时间: 2016-10-2 20:38
顶一个！太厉害了这题

作者: AnnieFFish 时间: 2016-10-23 22:11
看到关于DT总量的问题，终于明白了！

这道题真的拖了N久

感谢前辈们

作者: 钟无艳的威士忌 时间: 2016-10-24 15:09
想问一下如果dt的总量被其食物的可能性限制住了，那么当other species的数量增加以后，dt食物也增加了，那么dt的数量也会增加，那么吃mice的dt数量就不会减少呀。我就是这点想不明白，求解答！

作者: 钟无艳的威士忌 时间: 2016-10-24 15:09

itssuperoli 发表于 2016-9-9 04:49
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pic ...

想问一下如果dt的总量被其食物的可能性限制住了，那么当other species的数量增加以后，dt食物也增加了，那么dt的数量也会增加，那么吃mice的dt数量就不会减少呀。我就是这点想不明白，求解答！

作者: wttlll 时间: 2017-1-25 17:27

itssuperoli 发表于 2016-9-9 04:49
Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pic ...

同意！

作者: Jez 时间: 2017-3-14 17:24

钟无艳的威士忌发表于 2016-10-24 15:09
想问一下如果dt的总量被其食物的可能性限制住了，那么当other species的数量增加以后，dt食物也增加了，那 ...

http://forum.chasedream.com/thread-572325-1-1.html 5楼，我曾经和你一样哈哈

作者: Aiki-Shaw 时间: 2017-5-24 13:04
我们固化逻辑是总量不会发生变化，所以要想到这个

作者: 小灰灰养大鸟 时间: 2017-8-18 18:31
Suppose ticks=100, mice=50, others=50 (which will increase to 60)
P(eat mice)=1/2 P(eat others)=1/2
N(infected)=50 N(infected)=50

If ticks are not hungry, the number of ticks won’t increase because more food are provided.
P(eat mice)=5/11 P(eat others)=6/11
N(infected)=45 N(infected)=55
The aim can be achieved.

However, if they are hungry, the number of them will increase with the increasing food.
P(eat mice)=5/11 P(eat others)=6/11
N(infected)=50 N(infected)=60
The aim cann’t be achieved.

作者: Crystal0918 时间: 2018-8-28 17:10

waihou32 发表于 2013-5-2 22:46
我的理解是如果deer tick的数量不会被available feed所限制,那么这些tick根本就不会在乎对食物的选择,也就 ...

同意！

作者: kluivert 时间: 2018-8-29 01:38
这道题说的是the number of...是绝对数量，不是相对数量（百分比）

B 现有的dear tick 的数量是否受载体的多少限制
不受限制，那么意味着载体多了，那 tick 数量也多了，感染的tick数量应该也会多
受限制，那意味着载体变多了不会影响tick总数量，那那些在不会让tick感染的新的载体的出现,就会起到分流作用，有效的降低tick感染的数量

举个简单例子
一个盛满水的3L的水杯... 往2 个 10L的空水杯倒水
空水杯A ...干净
空水杯B .. 有点脏

所以在总水量确定的情况下，往A倒的多，干净水就多；反过来往B倒的多就是脏水多...互相牵扯，你多我少，你少我多
如果水总量不限制了，水更多了，那脏水可以最多达到10L ...和干净水没一点关系

道理就是如此

作者: SuriYang 时间: 2018-12-26 10:13
感谢分享！

作者: Yamm 时间: 2019-6-14 06:33
分享我的简单思路：（类比成我们能理解的例子）
Lyme disease is caused by a bacterium transmitted to humans by deer ticks疟疾通过蚊子传播给人类。. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected white-footed mice. 蚊子在幼虫时期喝臭水沟从而携带病菌。However, certain other species on which the larvae feed do not harbor the bacterium. 其他水沟没有病菌Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium―and hence the number of people contracting Lyme disease—would likely decline.如果没有病菌的水沟的数量增加了，那么这种携带病菌的蚊子的数量就下降。（暗含比例问题）
---------------------
文本分析：加强+if then
os：这个充分条件推出这个必要条件需要一个合理的解释。
命题重点在是否携带病菌的蚊子数量会下降。
------------------------
选项分析：
A 无关：携带病菌是否对蚊子有不良影响
B 无关：没有案例说人类的疟疾是他们喝臭水沟得的-与人类是否直接接触病原无关
C（ANS）：幼虫只进食一次，所以大概率上会吃到没有细菌的水沟-他们长大后就不会携带细菌。（取非削弱：幼虫有多次进食行为-幼虫早晚会吃到臭水沟）
D 无关:宿主是否能成为病菌的来源
E out of scope：与水沟是否携带其他病菌无关

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