[求助]大全20 (20/63) Q6

smartdummy

Species interdependence in nature confers many

benefits on the species involved, but it can also become a

point of weakness when one species involved in the rela-

tionship is affected by a catastrophe. Thus, flowering

(5) plant species dependent on insect pollination, as opposed

to self-pollination or wind pollination, could be endan-

gered when the population of insect-pollinators is depleted

by the use of pesticides.

   In the forests of New Brunswick, for example,

(10) various pesticides have been sprayed in the past 25 years

in efforts to control the spruce budworm, an economi-

cally significant pest. Scientists have now investigated

the effects of the spraying of Matacil, one of the anti-

budworm agents that is least toxic to insect-pollinators.

(15) They studied Matacil’s effects on insect mortality in a

wide variety of wild insect species and on plant fecun-

dity, expressed as the percentage of the total flowers on

an individual plant that actually developed fruit and

bore seeds. They found that the most pronounced

(20) mortality after the spraying of Matacil occurred among

the smaller bees and one family of flies, insects that were

all important pollinators of numerous species of plants

growing beneath the tree canopy of forests. The fecun-

dity of plants in one common indigenous species, the

(25) red-osier dogwood, was significantly reduced in the

sprayed areas as compared to that of plants in control

plots where Matacil was not sprayed. This species is

highly dependent on the insect-pollinators most vulner-

able to Matacil. The creeping dogwood, a species similar

(30) to the red-osier dogwood, but which is pollinated by

large bees, such as bumblebees, showed no significant

decline in fecundity. Since large bees are not affected by

the spraying of Matacil. These results and weight to the

argument that spraying where the pollinators are sensi-

(35) tive to the pesticide used decreases plant fecundity.

     The question of whether the decrease in plant fecun-

dity caused by the spraying of pesticides actually causes

a decline in the overall population of flowering plant

species still remains unanswered. Plant species dependent

(40) solely on seeds for survival or dispersal are obviously

more vulnerable to any decrease in plant fecundity that

occurs, whatever its cause. If, on the other hand, vegeta-

tive growth and dispersal (by means of shoots or runners)

are available as alternative reproductive strategies for a

(45) species, then decreases in plant fecundity may be of little consequence.

     The fecundity effects described here are

likely to have the most profound impact on plant species

with all four of the following characteristics: a short life

span, a narrow geographic range, an incapacity for vege-

(50) tative propagation, and a dependence on a small number

of insect-pollinator species. Perhaps we should give special

attention to the conservation of such plant species since

they lack key factors in their defenses against the envi-

ronmental disruption caused by pesticide use.

It can be inferred from the passage that which of the following plant species would be LEAST likely to experience a decrease in fecundity as a result of the spraying of a pesticide not directly toxic to plants?

(A) A flowering tree pollinated by only a few insect species

(B) A kind of insect-pollinated vine producing few flowers

(C) A wind-pollinated flowering tree that is short-lived

(D) A flowering shrub pollinated by a large number of insect species（C）

(E) A type of wildflower typically pollinated by larger insects

The key is C. Why?

I know wind-pollinated is fine, but short-lived is one of the 4 characteristics mentioned in line 48-51.

Thanks!

[此贴子已经被作者于2005-1-9 23:22:29编辑过]

wangyu73cn

我初步认为D是正确答案啊。

请大家指正。

爱睡觉的猫

我也觉得有问题，我选D，C好象和文章意思相反The fecundity effects described here are

likely to have the most profound impact on plant species

with all four of the following characteristics: a short life

span,

xjlv128

我也选D的！！

难道答案错了？C明显不对啊。。。

starskyly

支持D！

kimbol

1st paragraph.

Thus, flowering

(5) plant species dependent on insect pollination, as opposed

to self-pollination or wind pollination, could be endan-

gered when the population of insect-pollinators is depleted

by the use of pesticides.

it already mention flowering plant is doomed to be affected.

while wind pollination not.

cournot

这题C，

d不对，明明说pollinated by a large number of insect species，所以insect会受到影响fecundity当然会受到影响

jianlysmile

这道题我也不明白，我也选择了D。

哪位nn帮助指点一下，还是答案错了？

 

ssl507

Thus, flowering plant species dependent on insect pollination, as opposed to self-pollination or wind pollination, could be endangered when the population of insect-pollinators is depleted by the use of pesticides.

有此句得出，A wind-pollinated 完全不会受到pesticides的影响,所以为正确答案

never3738

同意楼上。做的时候压根就没考虑什么SHORT-LIVED的修饰短语。第一段直接就写了WIND POLLINATED 不会受到影响。