Directions: Read the passage. Then answer the questions. Give yourself 20 minutes to complete this practice set.

POPULATION AND CLIMATE

The human population on Earth has grown to the point that it is having an effect on Earth's atmosphere and ecosystems. Burning of fossil fuels, deforestation, urbanization, cultivation of rice and cattle, and the manufacture of chlorofluorocarbons (CFCs) for propellants and refrigerants are increasing the concentration of carbon dioxide, methane, nitrogen oxides, sulphur oxides, dust, and CFCs in the atmosphere. About 70 percent of the Sun's energy passes through the atmosphere and strikes Earth's surface. This radiation heats the surface of the land and ocean, and these surfaces then reradiate infrared radiation back into space. This allows Earth to avoid heating up too much. However, not all of the infrared radiation makes it into space; some is absorbed by gases in the atmosphere and is reradiated back to Earth's surface. A greenhouse gas is one that absorbs infrared radiation and then reradiates some of this radiation back to Earth. Carbon dioxide, CFCs, methane, and nitrogen oxides are greenhouse gases. The natural greenhouse effect of our atmosphere is well established. In fact, without greenhouse gases in the atmosphere, scientists calculate that Earth would be about 33℃ cooler than it currently is.
The current concentration of carbon dioxide in the atmosphere is about 360 parts per million. Human activities are having a major influence on atmospheric carbon dioxide concentrations, which are rising so fast that current predictions are that atmospheric concentrations of carbon dioxide will double in the next 50 to 100 years. The Intergovernmental Panel on Climate Change (IPCC) report in 1992, which represents a consensus of most atmospheric scientists, predicts that a doubling of carbon dioxide concentration would raise global temperatures anywhere between 1.4℃ and 4.5℃. The IPCC report issued in 2001 raised the temperature prediction almost twofold. The suggested rise in temperature is greater than the changes that occurred in the past between ice ages. The increase in temperatures would not be uniform, with the smallest changes at the equator and changes two or three times as great at the poles. The local effects of these global changes are difficult to predict, but it is generally agreed that they may include alterations in ocean currents, increased winter flooding in some areas of the Northern Hemisphere, a higher incidence of summer drought in some areas, and rising sea levels, which may flood low-lying countries.
Scientists are actively investigating the feedback mechanism within the physical, chemical, and biological components of Earth's climate system in order to make accurate predictions of the effects the rise in greenhouse gases will have on future global climates. Global circulation models are important tools in this process. These models incorporate current knowledge on atmospheric circulation patterns, ocean currents, the effect of landmasses, and the like to predict climate under changed conditions. There are several models, and all show agreement on a global scale. For example, all models show substantial changes in climate when carbon dioxide concentration is doubled. However, there are significant differences in the regional climates predicted by different models. Most models project greater temperature increases in mid-latitude regions and in mid-continental regions relative to the global average. Additionally, changes in precipitation patterns are predicted, with decreases in mid-latitude regions and increased rainfall in some tropical areas. Finally, most models predict that there will be increased occurrences of extreme events, such as extended periods without rain (drought), extreme heat waves, greater seasonal variation in temperatures, and increases in the frequency and magnitude of severe storms. Plants and animals have strong responses to virtually every aspect of these projected global changes.
The challenge of predicting organismal responses to global climate change is difficult. Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life.
The relative roles that abiotic and biotic factors play in the distribution of organisms is especially important now, when the world is confronted with the consequences of a growing human population. Changes in climate, land use, and habitat destruction are currently causing dramatic decreases in biodiversity throughout the world. An understanding of climate-organism relationships is essential to efforts to preserve and manage Earth's biodiversity.

单选题 The phrase "makes it" in the passage is closest in meaning to

• A. is reflected
• B. collects
• C. arrives
• D. blends

单选题 It can be inferred from paragraph 1 that one positive aspect of greenhouse gases is that they

• A. absorb 70 percent of the Sun's energy
• B. can be rapidly replenished in the atmosphere
• C. remove pollutants from ecosystems
• D. help keep Earth warm

单选题 According to paragraph 2, what can be said about the effects of global changes?

• A. The local plants and animals will be permanently damaged.
• B. It is hard to know exactly what form the local effects will take.
• C. Seawater levels will fall around the world.
• D. The effects will not occur in some regions of the world.

单选题 Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 2? Incorrect choices change the meaning in important ways or leave out essential information.

• A. The rapid rise of carbon dioxide concentrations can be attributed largely to the actions of humans.
• B. Predictions about atmospheric concentrations of carbon dioxide indicate that the influence of human activities will double soon.
• C. In the next 50 to 100 years, human activities will no longer have an influence on atmospheric carbon dioxide concentrations.
• D. Human activities can influence current predictions about atmospheric conditions.

单选题 The word "consensus" in the passage is closest in meaning to

• A. publication
• B. debate
• C. collection
• D. agreement

单选题 The phrase "this process" refers to

• A. the interaction between physical and biological components of Earth's climate system
• B. the increase of greenhouse gases in the atmosphere
• C. predicting future global climate
• D. global circulation models

单选题 According to paragraph 3, rainfall amounts are predicted to decrease in what parts of the world?

• A. In mid-latitude regions
• B. In tropical areas
• C. In mid-continental regions
• D. At the poles

单选题 The word "incorporate" in the passage is closest in meaning to

• A. describe
• B. include
• C. expand
• D. present

单选题 The word "virtually" in the passage is closest in meaning to

• A. nearly
• B. presumably
• C. usually
• D. visually

单选题 According to paragraph 3, climate models predict that all of the following events will occur with the increase in greenhouse gases EXCEPT

• A. greater seasonal temperature changes
• B. prolonged heat waves
• C. increased diversity of plants and animals
• D. longer dry periods

单选题 The author's main purpose in paragraph 5 is to

• A. explain the process of studying organism responses to climate change
• B. stress the importance of learning how climate affects plants and animals
• C. illustrate an important point about factors affecting biodiversity
• D. examine current research practices on the distribution of organisms on Earth

单选题 Look at the terms "greenhouse gas," "atmospheric circulation patterns," "global scale," and "biotic factors." Which of these terms is defined in the passage?

• A. Greenhouse gas
• B. Atmospheric circulation patterns
• C. Global scale
• D. Biotic factors

单选题 Look at the four squares [■] that indicate where the following sentence can be added to the passage.
Much of this work depends on the assumption that life forms adapted to a particular climate in the present were adapted to the same type of climate in the past.
Where would the sentence best fit?

• A. The challenge of predicting organismal responses to global climate change is difficult. Much of this work depends on the assumption that life forms adapted to a particular climate in the present were adapted to the same type of climate in the past. Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. ■ It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. ■ One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life. ■
• B. The challenge of predicting organismal responses to global climate change is difficult. ■ Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. Much of this work depends on the assumption that life forms adapted to a particular climate in the present were adapted to the same type of climate in the past. It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. ■ One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life. ■
• C. The challenge of predicting organismal responses to global climate change is difficult. ■ Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. ■ It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. Much of this work depends on the assumption that life forms adapted to a particular climate in the present were adapted to the same type of climate in the past. One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life. ■
• D. The challenge of predicting organismal responses to global climate change is difficult. ■ Partly, this is due to the fact that there are more studies of short-term, individual organism responses than there are of long-term, systemwide studies. ■ It is extremely difficult, both monetarily and physically, for scientists to conduct field studies at spatial and temporal scales that are large enough to include all the components of real-world systems, especially ecosystems with large, freely ranging organisms. ■ One way paleobiologists try to get around this limitation is to attempt to reconstruct past climates by examining fossil life. Much of this work depends on the assumption that life forms adapted to a particular climate in the present were adapted to the same type of climate in the past.

填空题 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.
Write your answer choices in the spaces where they belong. You can either write the letter of your answer choice or you can copy the sentence.
Human population on Earth is affecting both the atmosphere and the ecosystems.
·______
·______
·______

A. The survival of organisms on Earth is directly related to the amount of fossil fuels that are consumed.
B. Atmospheric carbon dioxide concentrations are rising quickly.
C. Scientists are working on ways to make precise forecasts of how the increase of greenhouse gases will affect Earth.
D. Scientists predict that temperature changes would be greater at the poles than at the equator.
E. Global circulation models can be used to measure the concentrations of chlorofluorocarbons in the atmosphere.
F. The ability to make accurate predictions about global climate presents several difficulties.