单选题
单选题
Climatic conditions are delicately adjusted to the composition of the Earth’s atmosphere. If there were a change in the atmosphere--for example, in the relative proportions of atmospheric gases"-the climate would probably change also. A slight increase in water vapor, for instance, would increase the heat-retaining capacity of the atmosphere and would lead to a rise in global temperatures. In contrast, a large increase in water vapor would increase the thickness and extent of the cloud layer, reducing the amount of solar energy reaching the Earth’s surface.
The level of carbon dioxide in the atmosphere has an important effect on climatic change. Most of the Earth’s incoming energy is short-wavelength radiation, which tends to pass through atmospheric carbon dioxide easily. The Earth, however, reradiates much of the received energy as long-wavelength radiation, which carbon dioxide absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by Venus, a planet covered by heavy clouds composed mostly of carbon dioxide, whose surface temperatures have been measured at 43012. If the carbon dioxide content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric carbon dioxide concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the carbon dioxide concentration would lead only to reduction in global temperatures of 312.
If, because of an increase in forest fires or volcanic activity, the carbon dioxide content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of carbon dioxide, would probably increase. As a consequence, plants would use more and more carbon dioxide. Eventually carbon dioxide levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; carbon dioxide would thereby be returned to the atmosphere and gradually the temperature would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of carbon dioxide present in the atmosphere, with regular temperature increases and decreases of a set magnitude.
Some climatologists argue that the burning of fossil fuels has raised the level of carbon dioxide in the atmosphere and has caused a global temperature increase of at least 1 C. But a supposed global temperature rise of 112 may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and mused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere Oceanic Zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations.
Which of the following questions does the passage supply information for answering
A:Why are projections of the effects of changes in water vapor levels oh the climate so inaccurate B:What are the steps in the process that takes place as carbon dioxide absorbs long-wave length radiation C:How might our understanding of the greenhouse effect be improved if the burning of fossil fuels were decreased D:What might cause a series of regular increases and decreases in the amount of carbon dioxide in the atmosphere
Climatic conditions are delicately adjusted to the composition of the Earth’s atmosphere. If there were a change in the atmosphere--for example, in the relative proportions of atmospheric gases"-the climate would probably change also. A slight increase in water vapor, for instance, would increase the heat-retaining capacity of the atmosphere and would lead to a rise in global temperatures. In contrast, a large increase in water vapor would increase the thickness and extent of the cloud layer, reducing the amount of solar energy reaching the Earth’s surface.
The level of carbon dioxide in the atmosphere has an important effect on climatic change. Most of the Earth’s incoming energy is short-wavelength radiation, which tends to pass through atmospheric carbon dioxide easily. The Earth, however, reradiates much of the received energy as long-wavelength radiation, which carbon dioxide absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by Venus, a planet covered by heavy clouds composed mostly of carbon dioxide, whose surface temperatures have been measured at 43012. If the carbon dioxide content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric carbon dioxide concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the carbon dioxide concentration would lead only to reduction in global temperatures of 312.
If, because of an increase in forest fires or volcanic activity, the carbon dioxide content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of carbon dioxide, would probably increase. As a consequence, plants would use more and more carbon dioxide. Eventually carbon dioxide levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; carbon dioxide would thereby be returned to the atmosphere and gradually the temperature would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of carbon dioxide present in the atmosphere, with regular temperature increases and decreases of a set magnitude.
Some climatologists argue that the burning of fossil fuels has raised the level of carbon dioxide in the atmosphere and has caused a global temperature increase of at least 1 C. But a supposed global temperature rise of 112 may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and mused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere Oceanic Zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations.
The author is primarily concerned with______.
A:explaining the effects that the burning of fossil fuels might have on climate B:illustrating the effects of carbon dioxide on atmospheric radiation C:discussing effects that changes in the carbon dioxide level in the atmosphere might have on climate D:challenging hypothesis about the effects of water vapor and carbon dioxide on climate
Text 3
Most growing plants contain much more water than all other materials combined. C. R. Bames has suggested that it is .as proper to term the plant a water structure as to call a house composed mainly of brick a brick building. Certainly it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the. soil solution before they can be taken into the root. They are carried to all parts of the growing plants and are built into essential plant materials while in a dissolved state.
The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars -- the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may
have much less water than growing tissues. The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll ( 叶落素 ) and with energy derived from light— to form sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor --to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80°F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A:the functions of carbon dioxide and water B:the role of water in a growing plant C:the process of simple sugar formation D:the synthesis of water with carbon dioxide
Text 3
Most growing plants contain much more water than all other materials combined. C. R. Bames has suggested that it is .as proper to term the plant a water structure as to call a house composed mainly of brick a brick building. Certainly it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the. soil solution before they can be taken into the root. They are carried to all parts of the growing plants and are built into essential plant materials while in a dissolved state.
The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars -- the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may
have much less water than growing tissues. The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll ( 叶落素 ) and with energy derived from light— to form sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor --to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80°F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A:forming sugars B:sustaining woody stems C:keeping green D:producing carbon dioxide
Text 3
Most growing plants contain much more water than all other materials combined. C. R. Bames has suggested that it is .as proper to term the plant a water structure as to call a house composed mainly of brick a brick building. Certainly it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the. soil solution before they can be taken into the root. They are carried to all parts of the growing plants and are built into essential plant materials while in a dissolved state.
The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars -- the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may
have much less water than growing tissues. The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll ( 叶落素 ) and with energy derived from light— to form sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor --to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80°F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A:to form sugars B:to derive energy from light C:to preserve water D:to combine carbon dioxide with water
Text 3
| Climatic conditions are delicately
adjusted to the composition of the Earth’s atmosphere. If there were a
change in the atmosphere--for example, in the relative proportions of
atmospheric gases"-the climate would probably change also. A slight increase in
water vapor, for instance, would increase the heat-retaining capacity of the
atmosphere and would lead to a rise in global temperatures. In contrast, a large
increase in water vapor would increase the thickness and extent of the cloud
layer, reducing the amount of solar energy reaching the Earth’s
surface. The level of carbon dioxide in the atmosphere has an important effect on climatic change. Most of the Earth’s incoming energy is short-wavelength radiation, which tends to pass through atmospheric carbon dioxide easily. The Earth, however, reradiates much of the received energy as long-wavelength radiation, which carbon dioxide absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by Venus, a planet covered by heavy clouds composed mostly of carbon dioxide, whose surface temperatures have been measured at 43012. If the carbon dioxide content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric carbon dioxide concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the carbon dioxide concentration would lead only to reduction in global temperatures of 312. If, because of an increase in forest fires or volcanic activity, the carbon dioxide content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of carbon dioxide, would probably increase. As a consequence, plants would use more and more carbon dioxide. Eventually carbon dioxide levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; carbon dioxide would thereby be returned to the atmosphere and gradually the temperature would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of carbon dioxide present in the atmosphere, with regular temperature increases and decreases of a set magnitude. Some climatologists argue that the burning of fossil fuels has raised the level of carbon dioxide in the atmosphere and has caused a global temperature increase of at least 1 C. But a supposed global temperature rise of 112 may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and mused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere Oceanic Zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations. |
A:Why are projections of the effects of changes in water vapor levels oh the climate so inaccurate B:What are the steps in the process that takes place as carbon dioxide absorbs long-wave length radiation C:How might our understanding of the greenhouse effect be improved if the burning of fossil fuels were decreased D:What might cause a series of regular increases and decreases in the amount of carbon dioxide in the atmosphere
Text 3
| Climatic conditions are delicately
adjusted to the composition of the Earth’s atmosphere. If there were a
change in the atmosphere--for example, in the relative proportions of
atmospheric gases"-the climate would probably change also. A slight increase in
water vapor, for instance, would increase the heat-retaining capacity of the
atmosphere and would lead to a rise in global temperatures. In contrast, a large
increase in water vapor would increase the thickness and extent of the cloud
layer, reducing the amount of solar energy reaching the Earth’s
surface. The level of carbon dioxide in the atmosphere has an important effect on climatic change. Most of the Earth’s incoming energy is short-wavelength radiation, which tends to pass through atmospheric carbon dioxide easily. The Earth, however, reradiates much of the received energy as long-wavelength radiation, which carbon dioxide absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by Venus, a planet covered by heavy clouds composed mostly of carbon dioxide, whose surface temperatures have been measured at 43012. If the carbon dioxide content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric carbon dioxide concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the carbon dioxide concentration would lead only to reduction in global temperatures of 312. If, because of an increase in forest fires or volcanic activity, the carbon dioxide content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of carbon dioxide, would probably increase. As a consequence, plants would use more and more carbon dioxide. Eventually carbon dioxide levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; carbon dioxide would thereby be returned to the atmosphere and gradually the temperature would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of carbon dioxide present in the atmosphere, with regular temperature increases and decreases of a set magnitude. Some climatologists argue that the burning of fossil fuels has raised the level of carbon dioxide in the atmosphere and has caused a global temperature increase of at least 1 C. But a supposed global temperature rise of 112 may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and mused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere Oceanic Zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations. |
A:explaining the effects that the burning of fossil fuels might have on climate B:illustrating the effects of carbon dioxide on atmospheric radiation C:discussing effects that changes in the carbon dioxide level in the atmosphere might have on climate D:challenging hypothesis about the effects of water vapor and carbon dioxide on climate
Text 3
Most growing plants contain much more water than all other materials combined. C. R. Bames has suggested that it is .as proper to term the plant a water structure as to call a house composed mainly of brick a brick building. Certainly it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the. soil solution before they can be taken into the root. They are carried to all parts of the growing plants and are built into essential plant materials while in a dissolved state.
The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form simple sugars -- the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may
have much less water than growing tissues. The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll ( 叶落素 ) and with energy derived from light— to form sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor --to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80°F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A:forming sugars B:sustaining woody stems C:keeping green D:producing carbon dioxide
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