In Colorado subalpine meadows, nonnative dandelions co-occur with a native flower, the larkspur. Bumblebees visit both species, creating the potential for interactions between the two species with respect to pollination. In a recent study, researchers selected 16 plots containing both species; all dandelions were removed from eight plots; the remaining eight control plots were left undisturbed. The control plots yielded significantly more larkspur seeds than the dandelion-free plots, leading the researchers to conclude that the presence of dandelions facilitates pollination (and hence seed production) in the native species by attracting more pollinators to the mixed plots.

Which of the following, if true, most seriously undermines the researchers' reasoning?


Bumblebees preferentially visit dandelions over larkspurs in mixed plots.

In mixed plots, pollinators can transfer pollen from one species to another to augment seed production.

If left unchecked, nonnative species like dandelions quickly crowd out native species.

Seed germination is a more reliable measure of a species' fitness than seed production.

Soil disturbances can result in fewer blooms, and hence lower seed production.

考题讲解

情景:在Colorado亚高山带的草地,非本地生物蒲公英和一种飞燕草生活在一起。黄蜂会把两种植物的花粉带到一起。研究人员选择16个块地。8个挖走了蒲公英,8个有蒲公英。他们发现凡是有蒲公英的试验地飞燕草长的都好,因此,是蒲公英让飞燕草长的好的。

推理:推理文段的前提说到了两件事,这两件事具有统计关联,即,凡是有蒲公英的试验地飞燕草长的都好。结论中给出了两者的因果关系。本题属于相关因果推理
前提:“蒲公英”和“飞燕草长的好”具有相关关系
结论:是蒲公英让飞燕草长的好的

选题方式:相关因果推理有四个评估方向,简而言之,即,答案选项要么同时提及“蒲公英”和“飞燕草长的好”,要么给“飞燕草长的好”另一个原因。

选项分析:

A选项:在混合试验地中,黄蜂更喜欢蒲公英。本选项和推理文段的因果均无关。

B选项:在混合试验地中,黄蜂可以把一个植物的花粉从它传播到另一个植物上来增加种子的产量。本选项同时提到了推理文段的因果。如果黄蜂没有这个能力,则其可以证明推理文段的因果之间没有关系,因此本选项可以加强推理文段。属于CQ1:因果联系问题。

C选项:如果不检查,那么非本地植物比如蒲公英将会迅速挤掉本地生物。本选项和推理文段的“果”无关。

D选项:
种子的萌芽是比种子的产量更可靠的去判断一个物种的健康的标准。本选项和推理文段的因果均无关。

E选项:
Correct. 土壤的打断(挖走蒲公英)可能会导致开花数量减少,并且因此导致更低的种子产出率。本选项可以解释为什么“飞燕草在有蒲公英的地方长的比较好”,这是不是因为蒲公英,而是因为另外一组的蒲公英被挖走,导致土壤被打断,自己长的不好。属于CQ4:独立第三因素问题

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