外研版（2019）必修第二册 Unit1 Food for thought 单元高考阅读课件（13张ppt)
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| 名称 | 外研版（2019）必修第二册 Unit1 Food for thought 单元高考阅读课件（13张ppt) |  | |
| 格式 | pptx | ||
| 文件大小 | 2.1MB | ||
| 资源类型 | 教案 | ||
| 版本资源 | 外研版（2019） | ||
| 科目 | 英语 | ||
| 更新时间 | 2023-02-26 16:37:58 | ||
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文档简介
(共13张PPT)
素养阅读系列
单元高考阅读
读有所获
阅读提示：本文为说明文，主题语境为人与自然，主题语境内容为自然环境。地球上的生态系统是如何运转的呢？物种之间有的关系非常紧密，有的关系疏远，科学家用数学模型来弄清生态系统运转的奥秘。本文有助于培养学生的思维品质。
读有所获
练有所得
词汇积累
长难句分析
学有所益
读有所获
How does an ecosystem (生态系统）work What makes the populations of different species the way they are Why are there so many flies and so few wolves To find an answer, scientists have built mathematical models of food webs, noting who eats whom and how much each one eats①.
With such models, scientists have found out some key principles operating in food webs. Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator(掠食动物)always eats huge numbers of a single prey (猎物)，the two species are strongly linked；when a predator lives on various species, they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species, it can survive the extinction(灭绝）of one of them. And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover②. The weak links may thus keep species from driving one another to extinction.
读有所获
Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems③. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.
And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean，we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.
Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, scientists say，because once ecosystems pass their tipping point (临界点），it is remarkably difficult for them to return.
答案:1.B.
答
案
解
析
1
练有所得
What have scientists discovered with the help of mathematical models of
food webs
A. The living habits of species in food webs.
B. The rules governing food webs of the ecosystems.
C. The approaches to studying the species in the ecosystems.
D. The differences between weak and strong links in food webs.
答案:2.C.
答
案
解
析
2
练有所得
A strong link is found between two species when a predator______.
A. has a wide food choice
B. can easily find new prey
C. sticks to one prey species
D. can quickly move to another place
答案:3.D.
答
案
解
析
3
练有所得
What will happen if the populations of top predators in a food web greatly decline
A. The prey species they directly attack will die out.
B. The species they indirectly attack will turn into top predators.
C. The living environment of other species will remain unchanged.
D. The populations of other species will experience unexpected changes.
答案:4.A.
答
案
解
析
4
练有所得
What conclusion can be drawn from the examples in Paragraph 4
A. Uncontrolled human activities greatly upset ecosystems.
B. Rapid economic development threatens animal habitats.
C. Species of commercial value dominate other species.
D. Industrial activities help keep food webs stable.
答案:5.D.
答
案
解
析
5
练有所得
How does an early-warning system help us maintain the ecological
balance
A. By getting illegal practices under control.
B. By stopping us from killing large predators.
C. By bringing the broken-down ecosystems back to normal.
D. By signaling the urgent need for taking preventive action.
1.mathematical model 数学模型
2.food web 食物网
3.note vt.记录；指出；注意
4.key principle 关键原则
5.consist of 由......组成
6.various adj.办各种各样的
7.dominate v.支配;控制
8.arrangement n.安排
9.stable 稳定的
10.reveal vt.显不；揭露
11.scale n.规模；比例
考纲词汇
学有所益
长难句分析
①句意：为了找到答案，科学家们建立了食物网的数学模型,记录谁吃谁，以及每个动物吃多少。
分析:句中不定式短语To find an answer作目的状语；现在分词短语noting...one eats作目的 状语。
②句意：当一种猎物变得稀少时，如果掠食动物可以转向更容易找到的另一种物种，那么这种转 变会使最初的那种猎物恢复数量。
分析:if引导的条件状语从句中有一个that引导的定语从句，还有一个when引导的时间状语从句。
③句意:数学模型也揭示出食物网可能是不稳 定的，在那里顶端的掠食动物的微小变化会给整个 生态系统带来巨大的影响。分析:这是一个主从复合句。that引导宾语从句；关系副词where引导非限制性定语从句，修饰先行词 food webs。
关注文章结论建议处，破解推理判断题。
一般情况下出现 the research indicates、the report suggests、scientists say等类似的结论建议性表 达方式时，表明此处为文中提及的研究或报告的结果，这些地方是命题人在命制推理判断题时格外青睐的。如左栏文章最后一段中的最后一句即是该篇文章的研究成果，第2小题命题点便出自此处。
学有所益
方法归纳
素养阅读系列
单元高考阅读
读有所获
阅读提示：本文为说明文，主题语境为人与自然，主题语境内容为自然环境。地球上的生态系统是如何运转的呢？物种之间有的关系非常紧密，有的关系疏远，科学家用数学模型来弄清生态系统运转的奥秘。本文有助于培养学生的思维品质。
读有所获
练有所得
词汇积累
长难句分析
学有所益
读有所获
How does an ecosystem (生态系统）work What makes the populations of different species the way they are Why are there so many flies and so few wolves To find an answer, scientists have built mathematical models of food webs, noting who eats whom and how much each one eats①.
With such models, scientists have found out some key principles operating in food webs. Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator(掠食动物)always eats huge numbers of a single prey (猎物)，the two species are strongly linked；when a predator lives on various species, they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species, it can survive the extinction(灭绝）of one of them. And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover②. The weak links may thus keep species from driving one another to extinction.
读有所获
Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems③. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.
And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean，we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.
Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, scientists say，because once ecosystems pass their tipping point (临界点），it is remarkably difficult for them to return.
答案:1.B.
答
案
解
析
1
练有所得
What have scientists discovered with the help of mathematical models of
food webs
A. The living habits of species in food webs.
B. The rules governing food webs of the ecosystems.
C. The approaches to studying the species in the ecosystems.
D. The differences between weak and strong links in food webs.
答案:2.C.
答
案
解
析
2
练有所得
A strong link is found between two species when a predator______.
A. has a wide food choice
B. can easily find new prey
C. sticks to one prey species
D. can quickly move to another place
答案:3.D.
答
案
解
析
3
练有所得
What will happen if the populations of top predators in a food web greatly decline
A. The prey species they directly attack will die out.
B. The species they indirectly attack will turn into top predators.
C. The living environment of other species will remain unchanged.
D. The populations of other species will experience unexpected changes.
答案:4.A.
答
案
解
析
4
练有所得
What conclusion can be drawn from the examples in Paragraph 4
A. Uncontrolled human activities greatly upset ecosystems.
B. Rapid economic development threatens animal habitats.
C. Species of commercial value dominate other species.
D. Industrial activities help keep food webs stable.
答案:5.D.
答
案
解
析
5
练有所得
How does an early-warning system help us maintain the ecological
balance
A. By getting illegal practices under control.
B. By stopping us from killing large predators.
C. By bringing the broken-down ecosystems back to normal.
D. By signaling the urgent need for taking preventive action.
1.mathematical model 数学模型
2.food web 食物网
3.note vt.记录；指出；注意
4.key principle 关键原则
5.consist of 由......组成
6.various adj.办各种各样的
7.dominate v.支配;控制
8.arrangement n.安排
9.stable 稳定的
10.reveal vt.显不；揭露
11.scale n.规模；比例
考纲词汇
学有所益
长难句分析
①句意：为了找到答案，科学家们建立了食物网的数学模型,记录谁吃谁，以及每个动物吃多少。
分析:句中不定式短语To find an answer作目的状语；现在分词短语noting...one eats作目的 状语。
②句意：当一种猎物变得稀少时，如果掠食动物可以转向更容易找到的另一种物种，那么这种转 变会使最初的那种猎物恢复数量。
分析:if引导的条件状语从句中有一个that引导的定语从句，还有一个when引导的时间状语从句。
③句意:数学模型也揭示出食物网可能是不稳 定的，在那里顶端的掠食动物的微小变化会给整个 生态系统带来巨大的影响。分析:这是一个主从复合句。that引导宾语从句；关系副词where引导非限制性定语从句，修饰先行词 food webs。
关注文章结论建议处，破解推理判断题。
一般情况下出现 the research indicates、the report suggests、scientists say等类似的结论建议性表 达方式时，表明此处为文中提及的研究或报告的结果，这些地方是命题人在命制推理判断题时格外青睐的。如左栏文章最后一段中的最后一句即是该篇文章的研究成果，第2小题命题点便出自此处。
学有所益
方法归纳