【请教】关于Lyme Disease的问题

晓野的野

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~~

guaiss

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

晓野的野

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

waihou32

十分不解啊！！！同问啊！！！！

waihou32

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；

naryi

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～～

leeng

楼上强悍！赞一个！

hu00033

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

奔奔宝贝

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。

september918

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！