首页
登录
职称英语
Narrator Listen to a part of a discussion in a biology class. [img]2011q1/ct
Narrator Listen to a part of a discussion in a biology class. [img]2011q1/ct
游客
2025-02-09
18
管理
问题
Narrator
Listen to a part of a discussion in a biology class.
[br] What is the talk mainly about?
[Professor] Now, let’s have a look at the bees. Until recently, we knew almost nothing about how important bees are in maintaining natural diversity. Now we know more about them. We know, for example, that honeybees are the dominant pollinators because they play a role in pollinating four out of five food crops in North America. We also know that honeybees, along with the other insects, bats, and birds that transfer pollen between flowers, all together they contribute more than ten billion dollars a year to fruit and see production on North American farms.
[Student A] Wow, It’s amazing. Pollination is so important for farming. [Professor] Yes, it is very important. Pollination is one of nature’s services to farmers. Just imagine about this: if we don’t have the pollinators, we would not have enough food to eat. We biologists never imagined we’d see the day when wild plants or crops suffered from pollinator scarcity. But, unfortunately, that day has come. In factor, farmers in Mexico and the states are suffering the worst pollinator crisis in history. So... what happened? Any idea?
[Student A] Is it... um... because of natural enemies? I read something about a kind of parasite that’s killed lots of bees.
[Professor] It’s true. An outbreak of parasite mites has caused a steep decline in North American populations of honeybees. But parasites aren’t the only factor.
[Student B] What about the pesticides used on farms? All those chemicals must have an effect.
[Professor] Most definitely, yes. Pesticides are a major factor. Both wild and domesticated bees are in serious trouble because of pesticides. In California, farm chemicals are killing around ten percent of all the honeybee colonies. Agriculture in general is part of the problem. Think about this for a minute, the North American continent is a vast collection of "nectar corridors" made up of flowering plants. Is there anybody who knows anything about these corridors?
[Student A] Yes. These corridors stretch for thousands of miles, from Mexico to as far north as Alaska.
[Professor] That’s right. And every year, there’s an array of migratory pollinators flying north and south with the seasons, following the flowers. The migratory corridors, the flyways... are like... uh... something like a path of stepping stones for the pollinators, with each "stone" being a collection of flowering plants. But our system of large scale agriculture has interfered. During the past fifty years millions of acres of desert in western Mexico and the southwestern United States have been turned into chemically intensive farms, planted with exotic grasses, creating huge stretches of flyway that are devoid of nectar producing plants for migratory pollinators. What we have now are huge gaps between the stepping stones... patches of plants here and there. A couple of migratory pollinators are worth noting. One is the lesser long nosed bat, and another is the most famous pollinator... what is our most famous pollinator? Or I should say our beautiful pollinator.
[Student B] Oh, I know. It’s the monarch butterfly!
[Professor] The monarch butterfly...yes. Millions of monarch butterflies all over the U.S. and southern Canada fly south every year in late summer. The monarch is the only butterfly that returns to a specific site year after year. Unfortunately the herbicides used on the milkweed in the Great Plains are taking a toll on monarchs, and fewer of them are reaching their winter grounds in Mexico. Another important pollinator is the long nosed bat. These amazing animals feed on cactus flowers. What they do is, they lap up the nectar at the bottom of the flower, and then when the bat flies off to another cactus, the pollen stuck to its head is transferred to that plant’s flower. But the long nosed bat is having a tough time, too. Some desert ranchers mistake them for vampire bats, and they’ve tried to poison them, or dynamite the caves where they roost.
29. What is the talk mainly about?
30. Based on the professor’s talk, what factors have contributed to the decline of pollinator populations? Click on two answers.
31. According to the professor, which is the most famous pollinator?
32. Based on the discussion, on the "steeping stones", what does the "stone" refer to?
Narrator Listen again to a part of the conversation. Then answer the question.
[Professor] But our system of large scale agriculture has interfered. During the past fifty years millions of acres of desert in western Mexico and the southwestern United States have been turned into chemically intensive farms, planted with exotic grasses, creating huge stretches of flyway that are devoid of nectar producing plants for migratory pollinators. What we have now are huge gaps between the stepping stones...patches of plants here and there.
33. Why does the professor say thisΩ?
Narrator Listen again to a part of the conversation. Then answer the question.
[Professor] Millions of monarch butterfly all over the U.S. and southern Canada fly south every year in late summer, The monarch is the only butterfly that returns to a specific site year after year. Unfortunately the herbicides used on the milkweed in the Great Plains are taking a toll on monarchs, and fewer of them are reaching their winter grounds in Mexico.
34. What can be inferred about monarch butterflies?
选项
A、The economic importance of bees.
B、A decline in pollinator populations.
C、How flowers are pollinated.
D、Nature’s services to farms.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3949010.html
相关试题推荐
NarratorListentoapartofadiscussioninabiologyclass.[img]2011q1/ct
NarratorListentoapartofadiscussioninabiologyclass.[img]2011q1/ct
NarratorListentoapartofatalkinahistorylecture.[img]2011q1/ct_etoe
NarratorListentoapartofatalkinahistorylecture.[img]2011q1/ct_etoe
NarratorListentoapartofatalkinahistorylecture.[img]2011q1/ct_etoe
NarratorListentoapartofatalkinahistorylecture.[img]2011q1/ct_etoe
NarratorListentoapartofaconversationinanoffice.[img]2011q1/ct_etoe
NarratorListentoapartofaconversationinanoffice.[img]2011q1/ct_etoe
NarratorListentoapartofaconversationinanoffice.[img]2011q1/ct_etoe
NarratorListentoapartofalectureinanecologyclass.[img]2011q1/ct_et
随机试题
[originaltext]Itwasprobablyaround3,000yearsagothatpeoplefirstbega
(1)WhentheDowrockets300pointsorthestocksofretailers,say,getdec
MicrosoftOfficeword是微软公司的一个文字处理器应用程序。
某公司2017年12月31日的长期负债及所有者权益总额为17000万元,其中,
孕妇,36岁,第一胎,宫内妊娠33周发现FGR。治疗1周复查NST无反应型,BP
事物阴阳两个方面的相互转化是A.绝对的 B.单方面的 C.量的变 D.有条
下列不属于祛湿类的药物是A木瓜丸 B胆宁片 C小活络丸 D开胸顺气丸 E
前列腺增生患者的术前护理下列哪项是错误的A.练习床上排尿 B.禁止饮酒及吸烟
城市国有土地使用权出让时,必须由城市规划主管部门提出规划条件。以下哪项不属于必须
修复体粘固后出现过敏性疼痛最不可能的原因是A.切割牙体后,牙髓处于激惹状态 B
最新回复
(
0
)