题目：
Prairie Diversity
1
Prairies—the grasslands that once covered immense areas of central North America—were created and maintained by factors that favored the growth of grasses over trees. These included an extremely variable climate, ranging from very hot to bitterly cold, with frequent periods of insufficient rainfall. Fires, started by lightning strikes or humans, also prevented the growth of trees, as did the millions of animals, particularly bison, that grazed (fed) on prairie plants. Because prairie plants grow to only a few feet above the ground, they are packed into a small space, creating an environment for competition above but especially below the soil. By some theories, in such an environment, there should be one species that can develop a strong competitive advantage that would allow it to outcompete and eliminate all the others over time.
The word “insufficient” in the passage is closest in meaning to
Vocabulary Questions词汇题
Aheavy
Bdamaging
Cnot normal
Dnot enough
2
Prairies—the grasslands that once covered immense areas of central North America—were created and maintained by factors that favored the growth of grasses over trees. These included an extremely variable climate, ranging from very hot to bitterly cold, with frequent periods of insufficient rainfall. Fires, started by lightning strikes or humans, also prevented the growth of trees, as did the millions of animals, particularly bison, that grazed (fed) on prairie plants. Because prairie plants grow to only a few feet above the ground, they are packed into a small space, creating an environment for competition above but especially below the soil. By some theories, in such an environment, there should be one species that can develop a strong competitive advantage that would allow it to outcompete and eliminate all the others over time.
Paragraph 1 suggests that human activities in prairies helped to do which of the following?
Inference Questions推理题
AReduce the number of fires that occurred there
BMaintain an environment favorable to prairie grasses
CIncrease the above-ground size of prairie plants by several feet
DDevelop a strong competitive advantage for animals such as bison
3
The reason this doesn’t happen is that disturbances knock back the most dominant or competitive species or individuals. Some species do well during a cool, wet summer versus a hot, dry summer. Some species do well immediately after a fire, while others do best several years after the last fire. Species respond both positively and negatively to being subjected to grazing. With all these different disturbances interacting on the landscape across space and time, and different species reacting differently to those disturbances, no one species is able to crowd out all others, and diversity is maintained. Most grazers target a specific group of plants in their diet. Bison and cattle both strongly prefer grasses over wildflowers, or forbs, as they are known scientifically. Their grazing removes the dominant plants—grasses—and makes room for the forbs. Grazing can increase plant diversity, sometimes almost doubling it.
The reason this doesn’t happen is that disturbances knock back the most dominant or competitive species or individuals. Some species do well during a cool, wet summer versus a hot, dry summer. Some species do well immediately after a fire, while others do best several years after the last fire. Species respond both positively and negatively to being subjected to grazing. With all these different disturbances interacting on the landscape across space and time, and different species reacting differently to those disturbances, no one species is able to crowd out all others, and diversity is maintained. Most grazers target a specific group of plants in their diet. Bison and cattle both strongly prefer grasses over wildflowers, or forbs, as they are known scientifically. Their grazing removes the dominant plants—grasses—and makes room for the forbs. Grazing can increase plant diversity, sometimes almost doubling it.
What is the author’s purpose in stating, “Some species do well immediately after a fire, while others do best several years after the last fire”?
Rhetorical Purpose Questions修辞目的题
ATo identify a factor that prevents a single prairie species from becoming too dominant
BTo demonstrate how well prairie species are able to withstand natural disturbances
CTo argue that fires do not significantly impact the distribution of prairie species
DTo contrast the effects of fire during a hot, dry summer with those during a cool, wet summer
4
The reason this doesn’t happen is that disturbances knock back the most dominant or competitive species or individuals. Some species do well during a cool, wet summer versus a hot, dry summer. Some species do well immediately after a fire, while others do best several years after the last fire. Species respond both positively and negatively to being subjected to grazing. With all these different disturbances interacting on the landscape across space and time, and different species reacting differently to those disturbances, no one species is able to crowd out all others, and diversity is maintained. Most grazers target a specific group of plants in their diet. Bison and cattle both strongly prefer grasses over wildflowers, or forbs, as they are known scientifically. Their grazing removes the dominant plants—grasses—and makes room for the forbs. Grazing can increase plant diversity, sometimes almost doubling it.
According to paragraph 2, how does grazing by bison and cattle affect prairie plants?
Factual Information Questions事实信息题
AIt removes some of the grasses, allowing wildflower populations to increase.
BIt can double the number of grasses in the prairie.
CIt lowers the diversity of species.
DIt removes many of the dominant forbs from the prairie.
5
Grazers also alter the structure of the vegetation. An ungrazed prairie appears homogeneous, a continuous canopy of evenly spaced grass seed heads waving in the wind, but in a grazed prairie, some areas will be heavily grazed and some lightly grazed, while other areas will show little sign of grazing. This creates a heterogeneous landscape. In these areas, there is habitat for grassland birds and other wildlife that prefer all types of nesting cover and foraging habitat. Grazers have other effects on the prairie. And here we should expand “grazing” to include animal disturbances more generally. Bison roll in the mud, creating small wetlands after rainstorms. Hoof action crushes some plants. Animal waste changes the fertility of the soil at small scales, making the prairie even more heterogeneous. Burrowing animals create holes and mounds of bare dirt, providing loose fertile soil, ideal for seed germination. Invertebrates that live in the soil, such as earthworms, expose the soil to air with their tunnels.
According to paragraph 3, which of the following occurs when animals create disturbances in the landscape?
Factual Information Questions事实信息题
AVegetation suitable for grazing declines, endangering grazing animals.
BWetlands become the dominant feature of the landscape.
CThe variety of nesting cover and foraging opportunities is reduced.
DA greater diversity of animal life can be supported.
6
Grazers also alter the structure of the vegetation. An ungrazed prairie appears homogeneous, a continuous canopy of evenly spaced grass seed heads waving in the wind, but in a grazed prairie, some areas will be heavily grazed and some lightly grazed, while other areas will show little sign of grazing. This creates a heterogeneous landscape. In these areas, there is habitat for grassland birds and other wildlife that prefer all types of nesting cover and foraging habitat. Grazers have other effects on the prairie. And here we should expand “grazing” to include animal disturbances more generally. Bison roll in the mud, creating small wetlands after rainstorms. Hoof action crushes some plants. Animal waste changes the fertility of the soil at small scales, making the prairie even more heterogeneous. Burrowing animals create holes and mounds of bare dirt, providing loose fertile soil, ideal for seed germination. Invertebrates that live in the soil, such as earthworms, expose the soil to air with their tunnels.
Paragraph 3 mentions all of the following as ways in which animals change the prairie EXCEPT
Negative Factual Information Questions否定事实信息题
Aturning areas of soil into wetlands
Busing hoof action to transport seed heads to new locations
Caffecting the fertility of the soil in certain areas
Dallowing more air to enter the soil
7
Because of the soil warming and direct sunlight on the soil surface, fires generally stimulate both plant growth and flowering. Productivity, the amount of plant material produced, will almost always be higher in burned prairies compared to unburned ones. Anyone who has spent any time in the prairie knows how well most plants flower in the summer following a fire. If fires occur too late in the spring, early-emerging species such as pasqueflower can be affected that year. Periodic fires, even late in the spring, probably do minimal damage to these species. Overall, almost all prairie plant species will respond positively to fire.
The word “Periodic” in the passage is closest in meaning to
Vocabulary Questions词汇题
AWidespread
BFast-moving
COccasional
DShort-lived
8
Because of the soil warming and direct sunlight on the soil surface, fires generally stimulate both plant growth and flowering. Productivity, the amount of plant material produced, will almost always be higher in burned prairies compared to unburned ones. Anyone who has spent any time in the prairie knows how well most plants flower in the summer following a fire. If fires occur too late in the spring, early-emerging species such as pasqueflower can be affected that year. Periodic fires, even late in the spring, probably do minimal damage to these species. Overall, almost all prairie plant species will respond positively to fire.
According to paragraph 5, which of the following is true about the response of most prairie plants to fire?
Factual Information Questions事实信息题
AThey respond better to late-spring fires than to early-spring fires.
BThey flower later in the year after a fire than they do during a year with no fire.
CThey grow taller in unburned prairies than they do in burned prairies.
DThey produce many flowers during the summer after a fire occurs.
9
Fire, another disturber in the tallgrass prairie, has both positive and negative effects on the plants and animals. ⬛First, it removes the insulating buildup of previous years’dead stems. ⬛This, in addition to the black ash left behind, warms the soil in the spring.⬛Unburned prairie can stay quite cold, even frozen, well into the spring.Second, fire causes the release of nitrogen as a gas.⬛While some nutrients, such as phosphorus, return to the soil in the ash, nitrogen is lost to the soil as it escapes into the atmosphere.
Look at the four squares ⬛ that indicate where the following sentence could be added to the passage
The absence of fire, however, can delay the effects of warmer weather on prairie land.Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
10
Several factors are responsible for creating and maintaining prairies.
Prose Summary Questions概要小结题
Select 3 answers
AThe competitive environment and packed space in prairie conditions causes prairie plants such as grasses to grow taller and provide more food for animals such as bison.
BGrazing promotes species diversity because it creates new habitats and nesting areas for animals and provides appropriate soil conditions for a variety of plant species to succeed.
CFires result in warmer soil in spring and, while they can have negative effects on plants and animals, they also lead to increased productivity and good conditions for grazing animals.
DVarious disturbances, including variations in climate from year to year, prevent a single species from maintaining a consistent competitive advantage.
EBison and cattle remove almost all vegetation wherever they graze, creating areas of wet, bare dirt that help to prevent spring wildfires from becoming too widespread.
FA layer of ash caused by a fire across large areas of grassland may briefly reduce plant productivity until phosphorus is returned to the soil.
