TF阅读真题第920篇Animal Migration Patterns in the Serengeti

Animal Migration Patterns in the Serengeti

 

The Serengeti, a region in northern Tanzania, is the site of the largest mammal migration on Earth. Herds of wildebeest, zebras, and gazelles leave the Serengeti Plain in the dry season, which makes sense. The grass there stops growing soon after the rains cease, quickly turning the plains into short dry stalks that cannot support a million or more big grazers. The wildebeest and zebras then head northwest, to the region of higher rainfall where there is still plenty of grass amid the acacia woodlands. They may spend several months here, but in November or December they will return to the plains. But why do they leave the woodlands again, especially after the rains have started and the amount of green forage (edible plant life) is increasing? It appears that the reverse migration back to the plain during the rainy season is driven by the need to acquire specific nutrients, particularly phosphorus. The concentration of phosphorus in the woodland forage appears to be below the required level. And phosphorus deficiencies may lead to reduced fertility and milk yield and to other problems during the reproductive season.

The journey of wildebeest, zebras, and gazelles, like the annual migration of birds, is an example of ecological opportunism. For much of the year, the Serengeti Plain is hot, dry, and uninviting; but when the long rains arrive, it very briefly becomes a nutritious green pasture, attracting nearly two million wildebeest, zebras, and gazelles. The herds could not survive there year-round; nor, apparently, can they subsist entirely on the less nutritious food of their dry-season range in the northwestern portion of the ecosystem. But by commuting between the two places, an immense population of grazers can sustain itself.

Compared with, say, a flock of geese winging its way across the autumn sky in precise V formation, the march of grazers across the Serengeti seems disorganized, unplanned, and at times even chaotic but, in fact, years of careful observation have shown that there is a definite order to the migration of zebras, wildebeest, and Thomson’s gazelles. This order is dictated in part by the tenfold difference in body size among the migrants, from 25-kilogram Thomson’s gazelles to 250-kilogram zebras, and in part by differences in digestive physiology. Not surprisingly, a zebra consumes a lot more food than a gazelle, and unlike the gazelle it can survive on a low- quality diet of grass that is high in fiber and low in proteins and nutrients. The zebra compensates for the poor quality of the food by consuming and processing a lot of it, essentially extracting a small amount of nutrition from a large volume of roughage. The gazelle, on the other hand, consumes much less forage than the zebra, but what it does eat is of high quality, consisting mostly of tender young shoots. A wildebeest is almost as big as a zebra, but, unlike a zebra, it is a ruminant. Ruminants have chambered stomachs that enable them to digest their food more thoroughly, thereby extracting a higher proportion of the protein locked within the plant tissue. However, because this slows the rate of digestion, a wildebeest cannot process as much food as a zebra and therefore requires slightly higher-quality food (but not as high quality as what a gazelle needs).

Scientists have discovered that as the dry season begins, the zebras leave the Serengeti Plain ahead of the wildebeest and Thomson’s gazelles. Moving out of the plains, they encounter the tall, rotting grass that has grown up in their absence from this part of the plains, much of it now dead and brown. Zebras are quite capable of surviving on this. They consume the coarse top stems and move on. By removing the long, coarse grass, the zebras inadvertently expose the more nutritious leaves and younger stems, which the wildebeest, following in the zebras’ wake, will eat. Over the course of a few days, the wildebeest reduce the grass to short dry stalks and bare earth, and once they have done so, they depart. The land then undergoes a rather remarkable transformation as green shoots emerge from the soil, their growth prompted by the removal of the dead and dying vegetation and the deposition of enormous amounts of wildebeest manure. Within a few weeks, what had looked like a wasteland after the wildebeest’s departure is a lush, green lawn, consisting largely of young shoots rich in protein and nutrients which provide the gazelles with an abundance of high-quality food.

 

 

 

 

 

 

 

1

The Serengeti, a region in northern Tanzania, is the site of the largest mammal migration on Earth. Herds of wildebeest, zebras, and gazelles leave the Serengeti Plain in the dry season, which makes sense. The grass there stops growing soon after the rains cease, quickly turning the plains into short dry stalks that cannot support a million or more big grazers. The wildebeest and zebras then head northwest, to the region of higher rainfall where there is still plenty of grass amid the acacia woodlands. They may spend several months here, but in November or December they will return to the plains. But why do they leave the woodlands again, especially after the rains have started and the amount of green forage (edible plant life) is increasing? It appears that the reverse migration back to the plain during the rainy season is driven by the need to acquire specific nutrients, particularly phosphorus. The concentration of phosphorus in the woodland forage appears to be below the required level. And phosphorus deficiencies may lead to reduced fertility and milk yield and to other problems during the reproductive season.

According to paragraph 1 ,zebras wildebeest ,and gazelles leave the Serengeti Plain in the dry season in order to

 

Rhetorical Purpose Questions修辞目的题

 

Aescape the heat

Bfind better food resources

Cavoid the migratory path of other grazers

Dengage in seasonal reproduction

2

The Serengeti, a region in northern Tanzania, is the site of the largest mammal migration on Earth. Herds of wildebeest, zebras, and gazelles leave the Serengeti Plain in the dry season, which makes sense. The grass there stops growing soon after the rains cease, quickly turning the plains into short dry stalks that cannot support a million or more big grazers. The wildebeest and zebras then head northwest, to the region of higher rainfall where there is still plenty of grass amid the acacia woodlands. They may spend several months here, but in November or December they will return to the plains. But why do they leave the woodlands again, especially after the rains have started and the amount of green forage (edible plant life) is increasing? It appears that the reverse migration back to the plain during the rainy season is driven by the need to acquire specific nutrients, particularly phosphorus. The concentration of phosphorus in the woodland forage appears to be below the required level. And phosphorus deficiencies may lead to reduced fertility and milk yield and to other problems during the reproductive season.

Paragraph 1 suggests which of the following about the food available to big grazers on the Serengeti Plain during the rainy season?

 

Inference Questions推理题

 

AThe food is mostly in the form of short dry stalks.

BThe food is more abundant than the food available in acacia woodlands at that time

CThe food contains nutrients that are important for the animals successful reproduction.

DThe food does not contain as much phosphorus as the animals need

3

The journey of wildebeest, zebras, and gazelles, like the annual migration of birds, is an example of ecological opportunism. For much of the year, the Serengeti Plain is hot, dry, and uninviting; but when the long rains arrive, it very briefly becomes a nutritious green pasture, attracting nearly two million wildebeest, zebras, and gazelles. The herds could not survive there year-round; nor, apparently, can they subsist entirely on the less nutritious food of their dry-season range in the northwestern portion of the ecosystem. But by commuting between the two places, an immense population of grazers can sustain itself.

Paragraph 2 supports which of the following ideas about the migration of zebras, wildebeest, and gazelles?

 

Factual Information Questions事实信息题

 

ATheir survival depends on migrating to the northwest portion of the ecosystem during the dry season.

BThey migrate at the same time of year as birds do

CThey commute back and forth between the Serengeti Plain and the northwest region many times each year.

DTheir herds improve their chances of surviving by evenly dividing their populations year-round between the northwest and the Serengeti ecosystems.

4

Compared with, say, a flock of geese winging its way across the autumn sky in precise V formation, the march of grazers across the Serengeti seems disorganized, unplanned, and at times even chaotic but, in fact, years of careful observation have shown that there is a definite order to the migration of zebras, wildebeest, and Thomson’s gazelles. This order is dictated in part by the tenfold difference in body size among the migrants, from 25-kilogram Thomson’s gazelles to 250-kilogram zebras, and in part by differences in digestive physiology. Not surprisingly, a zebra consumes a lot more food than a gazelle, and unlike the gazelle it can survive on a low- quality diet of grass that is high in fiber and low in proteins and nutrients. The zebra compensates for the poor quality of the food by consuming and processing a lot of it, essentially extracting a small amount of nutrition from a large volume of roughage. The gazelle, on the other hand, consumes much less forage than the zebra, but what it does eat is of high quality, consisting mostly of tender young shoots. A wildebeest is almost as big as a zebra, but, unlike a zebra, it is a ruminant. Ruminants have chambered stomachs that enable them to digest their food more thoroughly, thereby extracting a higher proportion of the protein locked within the plant tissue. However, because this slows the rate of digestion, a wildebeest cannot process as much food as a zebra and therefore requires slightly higher-quality food (but not as high quality as what a gazelle needs).

The word “thoroughly” in the passage is closest in meaning to

 

Vocabulary Questions词汇题

 

Anaturally

Bspecifically

Crapidly

Dcompletely

5

Compared with, say, a flock of geese winging its way across the autumn sky in precise V formation, the march of grazers across the Serengeti seems disorganized, unplanned, and at times even chaotic but, in fact, years of careful observation have shown that there is a definite order to the migration of zebras, wildebeest, and Thomson’s gazelles. This order is dictated in part by the tenfold difference in body size among the migrants, from 25-kilogram Thomson’s gazelles to 250-kilogram zebras, and in part by differences in digestive physiology. Not surprisingly, a zebra consumes a lot more food than a gazelle, and unlike the gazelle it can survive on a low- quality diet of grass that is high in fiber and low in proteins and nutrients. The zebra compensates for the poor quality of the food by consuming and processing a lot of it, essentially extracting a small amount of nutrition from a large volume of roughage. The gazelle, on the other hand, consumes much less forage than the zebra, but what it does eat is of high quality, consisting mostly of tender young shoots. A wildebeest is almost as big as a zebra, but, unlike a zebra, it is a ruminant. Ruminants have chambered stomachs that enable them to digest their food more thoroughly, thereby extracting a higher proportion of the protein locked within the plant tissue. However, because this slows the rate of digestion, a wildebeest cannot process as much food as a zebra and therefore requires slightly higher-quality food (but not as high quality as what a gazelle needs).

According to paragraph 3, why can the zebra survive on food that is low in proteins and nutrients?

 

Factual Information Questions事实信息题

 

AIt is large enough to store food for later digestion.

BIt consumes very large amounts of food.

CIts large size helps it to process food more efficiently.

DIt migrates to the more productive woodlands before the gazelle and wildebeest arrive.

6

Compared with, say, a flock of geese winging its way across the autumn sky in precise V formation, the march of grazers across the Serengeti seems disorganized, unplanned, and at times even chaotic but, in fact, years of careful observation have shown that there is a definite order to the migration of zebras, wildebeest, and Thomson’s gazelles. This order is dictated in part by the tenfold difference in body size among the migrants, from 25-kilogram Thomson’s gazelles to 250-kilogram zebras, and in part by differences in digestive physiology. Not surprisingly, a zebra consumes a lot more food than a gazelle, and unlike the gazelle it can survive on a low- quality diet of grass that is high in fiber and low in proteins and nutrients. The zebra compensates for the poor quality of the food by consuming and processing a lot of it, essentially extracting a small amount of nutrition from a large volume of roughage. The gazelle, on the other hand, consumes much less forage than the zebra, but what it does eat is of high quality, consisting mostly of tender young shoots. A wildebeest is almost as big as a zebra, but, unlike a zebra, it is a ruminant. Ruminants have chambered stomachs that enable them to digest their food more thoroughly, thereby extracting a higher proportion of the protein locked within the plant tissue. However, because this slows the rate of digestion, a wildebeest cannot process as much food as a zebra and therefore requires slightly higher-quality food (but not as high quality as what a gazelle needs).

According to paragraph 3, which of the following characterizes the consumption behavior of gazelles?

 

Factual Information Questions事实信息题

 

AGazelles are unable to process the food they consume as rapidly as wildebeests can.

BGazelles can satisfy their nutritional needs by eating small amounts of high-quality food.

CGazelles can digest a larger volume of food than zebras can.

DGazelles’ small size allows them to survive on a low-protein diet.

7

Compared with, say, a flock of geese winging its way across the autumn sky in precise V formation, the march of grazers across the Serengeti seems disorganized, unplanned, and at times even chaotic but, in fact, years of careful observation have shown that there is a definite order to the migration of zebras, wildebeest, and Thomson’s gazelles. This order is dictated in part by the tenfold difference in body size among the migrants, from 25-kilogram Thomson’s gazelles to 250-kilogram zebras, and in part by differences in digestive physiology. Not surprisingly, a zebra consumes a lot more food than a gazelle, and unlike the gazelle it can survive on a low- quality diet of grass that is high in fiber and low in proteins and nutrients. The zebra compensates for the poor quality of the food by consuming and processing a lot of it, essentially extracting a small amount of nutrition from a large volume of roughage. The gazelle, on the other hand, consumes much less forage than the zebra, but what it does eat is of high quality, consisting mostly of tender young shoots. A wildebeest is almost as big as a zebra, but, unlike a zebra, it is a ruminant. Ruminants have chambered stomachs that enable them to digest their food more thoroughly, thereby extracting a higher proportion of the protein locked within the plant tissue. However, because this slows the rate of digestion, a wildebeest cannot process as much food as a zebra and therefore requires slightly higher-quality food (but not as high quality as what a gazelle needs).

Scientists have discovered that as the dry season begins, the zebras leave the Serengeti Plain ahead of the wildebeest and Thomson’s gazelles. Moving out of the plains, they encounter the tall, rotting grass that has grown up in their absence from this part of the plains, much of it now dead and brown. Zebras are quite capable of surviving on this. They consume the coarse top stems and move on. By removing the long, coarse grass, the zebras inadvertently expose the more nutritious leaves and younger stems, which the wildebeest, following in the zebras’ wake, will eat. Over the course of a few days, the wildebeest reduce the grass to short dry stalks and bare earth, and once they have done so, they depart. The land then undergoes a rather remarkable transformation as green shoots emerge from the soil, their growth prompted by the removal of the dead and dying vegetation and the deposition of enormous amounts of wildebeest manure. Within a few weeks, what had looked like a wasteland after the wildebeest’s departure is a lush, green lawn, consisting largely of young shoots rich in protein and nutrients which provide the gazelles with an abundance of high-quality food.

Which of the following statements best describes the relationship between paragraphs 3 and 4 in the passage?

Organization Questions组织结构题

AParagraph 3 describes the physical differences among the migrating animals, and paragraph 4 explains how these differences advantage some animals over others.

BParagraph 3 explains how some animals obtain enough nutrition during migration, and paragraph 4 explains why other migrating animals do not.

CParagraph 4 discusses how the migrating animals’ food preferences examined in paragraph 3 change throughout the year.

DParagraph 4 presents the migrating animals’ order of migration, based on their nutritional needs described in paragraph 3.

8

Scientists have discovered that as the dry season begins, the zebras leave the Serengeti Plain ahead of the wildebeest and Thomson’s gazelles. Moving out of the plains, they encounter the tall, rotting grass that has grown up in their absence from this part of the plains, much of it now dead and brown. Zebras are quite capable of surviving on this. They consume the coarse top stems and move on. By removing the long, coarse grass, the zebras inadvertently expose the more nutritious leaves and younger stems, which the wildebeest, following in the zebras’ wake, will eat. Over the course of a few days, the wildebeest reduce the grass to short dry stalks and bare earth, and once they have done so, they depart. The land then undergoes a rather remarkable transformation as green shoots emerge from the soil, their growth prompted by the removal of the dead and dying vegetation and the deposition of enormous amounts of wildebeest manure. Within a few weeks, what had looked like a wasteland after the wildebeest’s departure is a lush, green lawn, consisting largely of young shoots rich in protein and nutrients which provide the gazelles with an abundance of high-quality food.

According to paragraph4,why are gazelles able to obtain a large amount of nutritious food after the dry season has begun in the Serengeti?

 

Factual Information Questions事实信息题

 

AGazelles deposit large amounts of manure that helps grass grow.

BZebras and wildebeest avoid eating the dried grass that gazelles

CThe actions of wildebeest result in the appearance of high quality grass after the wildebeest leave.

DThe dead and dying vegetation that the wildebeest leave is rich in protein and other nutrients

9

The Serengeti, a region in northern Tanzania, is the site of the largest mammal migration on Earth. [■] Herds of wildebeest, zebras, and gazelles leave the Serengeti Plain in the dry season, which makes sense. [■] The grass there stops growing soon after the rains cease, quickly turning the plains into short dry stalks that cannot support a million or more big grazers. [■] The wildebeest and zebras then head northwest, to the region of higher rainfall where there is still plenty of grass amid the acacia woodlands. They may spend several months here, but in November or December they will return to the plains. But why do they leave the woodlands again, especially after the rains have started and the amount of green forage (edible plant life) is increasing? [■]  It appears that the reverse migration back to the plain during the rainy season is driven by the need to acquire specific nutrients, particularly phosphorus. The concentration of phosphorus in the woodland forage appears to be below the required level. And phosphorus deficiencies may lead to reduced fertility and milk yield and to other problems during the reproductive season.

Look at the four squares [■]  that indicate where the following sentence could be added to the passage

Otherwise, they would not be able to satisfy their demand for food.Insert Text Questions句子插入题

Where would the sentence best fit？Click on a square  sentence to the passage.

10

The large grazers of the serengeti Plain have a specific pattern of migration.

 

Prose Summary Questions概要小结题

 

Select 3 answers

AIn order to improve their ability to reproduce successfully, the large mammals of the Serengeti migrate to the wetter woodlands just before the reproductive season begins.

BThe different species of grazers have different nutritional needs, which depend on the animals’ size and stomach characteristics and determine the order of migration.

CSome grazers have adapted to eating short dry stalks by evolving stomachs that can extract a fairly large amount of proteins and other nutrients from a small volume of forage

DDuring the dry season zebras, wildebeest, and gazelles migrate to the acacia woodlands, where there is still a large amount of edible grass available.

EDespite their smaller size, gazelles can successfully compete with zebras and wildebeest for the highest-quality grass because gazelles migrate to the Serengeti Plain shortly after the rainy season begins.

FMigrating animals prepare the way for later-migrating species by consuming the food best suited to them and leaving food that is better suited to the animals that come after them.