《,高考真题,》,2019年,高考,英语,母题,题源,专题06    阅读理解（环保类）

【母题来源一】【2019·北京卷，D】环保类
By the end of the century，if not sooner，the world's oceans will be bluer and greener thanks to a warming climate，according to a new study.
At the heart of the phenomenon lie tiny marine microorganisms(海洋微生物)called phytoplankton. Because of the way light reflects off the organisms，these phytoplankton create colourful patterns at the ocean surface. Ocean colour varies from green to blue，depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas，while reducing it in other spots，leading to changes in the ocean's appearance.
Phytoplankton live at the ocean surface，where they pull carbon dioxide(二氧化碳)into the ocean while giving off oxygen. When these organisms die，they bury carbon in the deep ocean，an important process that helps to regulate the global climate. But phytoplankton are vulnerable to the ocean's warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth，since they need not only sunlight and carbon dioxide to grow，but also nutrients.
Stephanie Dutkiewicz，a scientist in MIT's Center for Global Change Science，built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃，it found that multiple changes to the colour of the oceans would occur. The model projects that currently blue areas with little phytoplankton could become even bluer. But in some waters，such as those of the Arctic，a warming will make conditions riper for phytoplankton，and these areas will turn greener. “Not only are the quantities of phytoplankton in the ocean changing. ”she said，“but the type of phytoplankton is changing. ”
42. What are the first two paragraphs mainly about?
A. The various patterns at the ocean surface.
B. The cause of the changes in ocean colour.
C. The way light reflects off marine organisms.
D. The efforts to fuel the growth of phytoplankton.
43. What does the underlined word “vulnerable” in Paragraph 3 probably mean?
A. Sensitive.    B. Beneficial    C. Significant    D. Unnoticeable
44. What can we learn from the passage?
A. Phytoplankton play a declining role in the marine ecosystem.
B. Dutkiewicz's model aims to project phytoplankton changes
C. Phytoplankton have been used to control global climate
D. Oceans with more phytoplankton may appear greener.
45. What is the main purpose of the passage。
A. To assess the consequences of ocean colour changes
B. To analyse the composition of the ocean food chain
C. To explain the effects of climate change on oceans
D. To introduce a new method to study phytoplankton

【母题来源二】 
【2019·天津卷，C】环保类
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 eats.
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 recover. The weak links may thus keep species from driving one another to extinction.
Mathematical models have also revealed that food webs may be unstable，where small changes of top predators can lead to big effects throughout entire ecosystems. 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 says because once ecosystems pass their tipping point（临界点），it is remarkably difficult for them to return.
46. What have scientists discovered with the help of mathematical models of food webs。
A. The living habits of species in food webs.。

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