TF阅读真题第857篇Desert Adaptation in Kangaroo Rats

 

 

The desert kangaroo rat of western North America has adapted wonderfully to its dry  environment, and in fact it rarely goes thirsty. Mammals lose water in three ways: when they  breathe, sweat, or urinate. Water is lost through breathing, which mammals do to acquire the oxygen necessary for carrying out the chemical functions within cells that [Highlight]sustain life and for getting rid of carbon dioxide, a waste product. Water is lost in the process because it is a physiological requirement that oxygen be absorbed across a wet membrane. The insides of mammalian lungs have a nice wet membrane, and when they breathe out, some water is exhaled as water vapor. Mammals generally sweat to cool their bodies down because evaporation of water removes heat. Animals urinate to remove nitrogenous waste from their bodies because nitrogen is a toxic by-product of digesting food, particularly proteins. If a mammal did not urinate (or if its kidneys shut down), it would quickly build up too much  nitrogen, its blood would become toxic, and it would die.

If we look to the kangaroo rat, however, we can see that evolution has equipped this animal with a host of amazing adaptations to help it conserve precious water in its desert environment. First we turn to the kangaroo rat’s nose, through which it breathes. The rat’s nasal passages are set up in such a way that it is able to conserve and recover some of the water from its breath. In these passages, warm, moist air leaving the lungs comes into contact with cooler, drier air entering the lungs and loses some of its warmth to this cooler air. Thus  the breath leaving the lungs cools as it nears the outside, allowing water vapor in the breath to condense (change to a liquid) in the nasal passages since cool air holds less water than warm air. This relatively simple mechanism allows the kangaroo rat to recover somewhere between 50 percent and 80 percent of the water in its breath, making it very water-efficient

Another astonishing fact about this kangaroo rat is that it does not drink water.In the deserts where these rodents live, they can’t rely on free water because they rarely encounter it. If they don’t drink water, why don’t they die of thirst, you might ask. One way they get water is through their food. When they break down food during digestion, one of the by-products is water. For demonstration  purposes, we will represent all food using the simple sugar glucose, which has the chemical formula CC6 HH12 OO6. Digestion of glucose requires oxygen (O2) and breaks this sugar into carbon dioxide(CO2) and water (H2O), releasing energy. For every molecule of glucose digested, we get six water molecules. This process is not unique to kangaroo rats; it happens when we digest food as well, but these rats are more efficient at generating and using this water. In addition, kangaroo rats are seed eaters and they will often cache, or bury, their seeds underground, where the temperature is significantly cooler. These seeds are bone-dry when collected at the desert surface, but when they are put into cool underground caches, they act like little sponges, sucking up some of the moisture from the surrounding soil. So kangaroo rats also get some water from the way they handle and process food.

When we look at water loss through sweating, we find that kangaroo rats have solved this problem by staying in their burrows, limiting the time they spend out in the hot Sun. In fact, they don’t sweat much because they run around at night, when it is significantly cooler and there is no sunlight to dry them out. Finally, in terms of water loss through urine, kangaroo rats have a specialized kidney that is five times more efficient than that of humans at removing water from their nitrogenous waste. So efficient are the kidneys that the kangaroo rat’s urine is excreted more as a paste than a liquid, saving it large volumes of water. With all of these physiological and behavioral adaptations, the kangaroo rat is a model of water conservation, which allows it to live in the harsh, dry desert.

 

 

 

 

 

 

1

The desert kangaroo rat of western North America has adapted wonderfully to its dry  environment, and in fact it rarely goes thirsty. Mammals lose water in three ways: when they  breathe, sweat, or urinate. Water is lost through breathing, which mammals do to acquire the oxygen necessary for carrying out the chemical functions within cells that [Highlight]sustain life and for getting rid of carbon dioxide, a waste product. Water is lost in the process because it is a physiological requirement that oxygen be absorbed across a wet membrane. The insides of mammalian lungs have a nice wet membrane, and when they breathe out, some water is exhaled as water vapor. Mammals generally sweat to cool their bodies down because evaporation of water removes heat. Animals urinate to remove nitrogenous waste from their bodies because nitrogen is a toxic by-product of digesting food, particularly proteins. If a mammal did not urinate (or if its kidneys shut down), it would quickly build up too much  nitrogen, its blood would become toxic, and it would die.

According to paragraph 1, all of the following occur when mammals lose water from the body through various ways EXCEPT:

Negative Factual Information Questions否定事实信息题

AChemical functions within cells become limited.

BCarbon dioxide is removed from the body.

CThe body becomes cooler.

DThe body is cleansed of poisonous chemicals

 

2

The desert kangaroo rat of western North America has adapted wonderfully to its dry  environment, and in fact it rarely goes thirsty. Mammals lose water in three ways: when they  breathe, sweat, or urinate. Water is lost through breathing, which mammals do to acquire the oxygen necessary for carrying out the chemical functions within cells that [Highlight]sustain life and for getting rid of carbon dioxide, a waste product. Water is lost in the process because it is a physiological requirement that oxygen be absorbed across a wet membrane. The insides of mammalian lungs have a nice wet membrane, and when they breathe out, some water is exhaled as water vapor. Mammals generally sweat to cool their bodies down because evaporation of water removes heat. Animals urinate to remove nitrogenous waste from their bodies because nitrogen is a toxic by-product of digesting food, particularly proteins. If a mammal did not urinate (or if its kidneys shut down), it would quickly build up too much  nitrogen, its blood would become toxic, and it would die.

According to paragraph 1, for which of the following reasons is it necessary for mammals to remove nitrogen from their bodies?

Factual Information Questions事实信息题

ANitrogen removal allows urination to occur.

BNitrogen removal prevents the kidneys from shutting down.

CNitrogen removal prevents the blood from being poisoned.

DNitrogen removal allows for efficient digestion of food.

 

3

If we look to the kangaroo rat, however, we can see that evolution has equipped this animal with a host of amazing adaptations to help it conserve precious water in its desert environment. First we turn to the kangaroo rat’s nose, through which it breathes. The rat’s nasal passages are set up in such a way that it is able to conserve and recover some of the water from its breath. In these passages, warm, moist air leaving the lungs comes into contact with cooler, drier air entering the lungs and loses some of its warmth to this cooler air. Thus  the breath leaving the lungs cools as it nears the outside, allowing water vapor in the breath to condense (change to a liquid) in the nasal passages since cool air holds less water than warm air. This relatively simple mechanism allows the kangaroo rat to recover somewhere between 50 percent and 80 percent of the water in its breath, making it very water-efficient

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

Vocabulary Questions词汇题

Avaluable

Bavailable

Csufficient

Dneeded

 

4

If we look to the kangaroo rat, however, we can see that evolution has equipped this animal with a host of amazing adaptations to help it conserve precious water in its desert environment. First we turn to the kangaroo rat’s nose, through which it breathes. The rat’s nasal passages are set up in such a way that it is able to conserve and recover some of the water from its breath. In these passages, warm, moist air leaving the lungs comes into contact with cooler, drier air entering the lungs and loses some of its warmth to this cooler air. Thus  the breath leaving the lungs cools as it nears the outside, allowing water vapor in the breath to condense (change to a liquid) in the nasal passages since cool air holds less water than warm air. This relatively simple mechanism allows the kangaroo rat to recover somewhere between 50 percent and 80 percent of the water in its breath, making it very water-efficient

Why does the author state that “cool air holds less water than warm air”?

Rhetorical Purpose Questions修辞目的题

ATo indicate that the kangaroo rat is able to recover more water from warm air than from cold air

BTo explain why kangaroo rats are able to breathe efficiently through their nasal passages

CTo help explain why the kangaroo rat is able to recover some of the water from its breath

DTo demonstrate that water vapor condensation has a limited effect on the kangaroo rat’s ability to conserve water

 

5

Another astonishing fact about this kangaroo rat is that it does not drink water.In the deserts where these rodents live, they can’t rely on free water because they rarely encounter it. If they don’t drink water, why don’t they die of thirst, you might ask. One way they get water is through their food. When they break down food during digestion, one of the by-products is water. For demonstration  purposes, we will represent all food using the simple sugar glucose, which has the chemical formula CC6 HH12 OO6. Digestion of glucose requires oxygen (O2) and breaks this sugar into carbon dioxide(CO2) and water (H2O), releasing energy. For every molecule of glucose digested, we get six water molecules. This process is not unique to kangaroo rats; it happens when we digest food as well, but these rats are more efficient at generating and using this water. In addition, kangaroo rats are seed eaters and they will often cache, or bury, their seeds underground, where the temperature is significantly cooler. These seeds are bone-dry when collected at the desert surface, but when they are put into cool underground caches, they act like little sponges, sucking up some of the moisture from the surrounding soil. So kangaroo rats also get some water from the way they handle and process food.

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

Vocabulary Questions词汇题

Aappropriately

Bgenerally

Cobviously

Dconsiderably

 

6

Another astonishing fact about this kangaroo rat is that it does not drink water.In the deserts where these rodents live, they can’t rely on free water because they rarely encounter it. If they don’t drink water, why don’t they die of thirst, you might ask. One way they get water is through their food. When they break down food during digestion, one of the by-products is water. For demonstration  purposes, we will represent all food using the simple sugar glucose, which has the chemical formula CC6 HH12 OO6. Digestion of glucose requires oxygen (O2) and breaks this sugar into carbon dioxide(CO2) and water (H2O), releasing energy. For every molecule of glucose digested, we get six water molecules. This process is not unique to kangaroo rats; it happens when we digest food as well, but these rats are more efficient at generating and using this water. In addition, kangaroo rats are seed eaters and they will often cache, or bury, their seeds underground, where the temperature is significantly cooler. These seeds are bone-dry when collected at the desert surface, but when they are put into cool underground caches, they act like little sponges, sucking up some of the moisture from the surrounding soil. So kangaroo rats also get some water from the way they handle and process food.

According to paragraph 3, in which of the following ways does kangaroo rat digestion differ from human digestion?

Factual Information Questions事实信息题

AKangaroo rats are better able to use the water produced by digestion.

BKangaroo rats break down glucose into a larger number of molecules.

CKangaroo rats require much less water to properly digest their food.

DKangaroo rats use more energy during digestion.

 

7

Another astonishing fact about this kangaroo rat is that it does not drink water.In the deserts where these rodents live, they can’t rely on free water because they rarely encounter it. If they don’t drink water, why don’t they die of thirst, you might ask. One way they get water is through their food. When they break down food during digestion, one of the by-products is water. For demonstration  purposes, we will represent all food using the simple sugar glucose, which has the chemical formula CC6 HH12 OO6. Digestion of glucose requires oxygen (O2) and breaks this sugar into carbon dioxide(CO2) and water (H2O), releasing energy. For every molecule of glucose digested, we get six water molecules. This process is not unique to kangaroo rats; it happens when we digest food as well, but these rats are more efficient at generating and using this water. In addition, kangaroo rats are seed eaters and they will often cache, or bury, their seeds underground, where the temperature is significantly cooler. These seeds are bone-dry when collected at the desert surface, but when they are put into cool underground caches, they act like little sponges, sucking up some of the moisture from the surrounding soil. So kangaroo rats also get some water from the way they handle and process food.

Paragraph 3 suggests which of the following about the seeds collected on the surface by kangaroo rats?

Inference Questions推理题

AThey provide kangaroo rats with much greater amounts of water than glucose does.

BThey are easier to process for kangaroo rats than glucose is.

CThey become much easier to digest after being buried in cool soil.

DThey help kangaroo rats to avoid dying of thirst only if eaten after being buried in the ground for some time.

 

8

When we look at water loss through sweating, we find that kangaroo rats have solved this problem by staying in their burrows, limiting the time they spend out in the hot Sun. In fact, they don’t sweat much because they run around at night, when it is significantly cooler and there is no sunlight to dry them out. Finally, in terms of water loss through urine, kangaroo rats have a specialized kidney that is five times more efficient than that of humans at removing water from their nitrogenous waste. So efficient are the kidneys that the kangaroo rat’s urine is excreted more as a paste than a liquid, saving it large volumes of water. With all of these physiological and behavioral adaptations, the kangaroo rat is a model of water conservation, which allows it to live in the harsh, dry desert.

Which of the following is NOT mentioned in paragraph 4 about how kangaroo rats reduce water loss?

Negative Factual Information Questions否定事实信息题

AKangaroo rats have specialized organs that prevent them from sweating much.

BKangaroo rats limit the time they stay outside their burrows when the Sun is hot.

CKangaroo rats are most active outside their burrows at night.

DKangaroo rats release urine in paste form.

 

9

[■]Another astonishing fact about this kangaroo rat is that it does not drink water. [■]In the deserts where these rodents live, they can’t rely on free water because they rarely encounter it. [■]If they don’t drink water, why don’t they die of thirst, you might ask. [■]One way they get water is through their food. When they break down food during digestion, one of the by-products is water. For demonstration  purposes, we will represent all food using the simple sugar glucose, which has the chemical formula CC6 HH12 OO6. Digestion of glucose requires oxygen (O2) and breaks this sugar into carbon dioxide(CO2) and water (H2O), releasing energy. For every molecule of glucose digested, we get six water molecules. This process is not unique to kangaroo rats; it happens when we digest food as well, but these rats are more efficient at generating and using this water. In addition, kangaroo rats are seed eaters and they will often cache, or bury, their seeds underground, where the temperature is significantly cooler. These seeds are bone-dry when collected at the desert surface, but when they are put into cool underground caches, they act like little sponges, sucking up some of the moisture from the surrounding soil. So kangaroo rats also get some water from the way they handle and process food.

Look at the four squaresthat indicate where the following sentence could be added to the passage

The environment has a lot to do with this characteristic of the kangaroo rat.

Insert Text Questions句子插入题

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

10

The desert kangaroo rat of western North America has adapted very well to its dry environment

Prose Summary Questions概要小结题

Select 3 answers

ADespite the need to conserve water, the kangaroo rat loses water in the same ways that other mammals do in order to cool its body in the hot desert environment.

BThe structure of the kangaroo rat’s nasal passages allows water leaving the lungs to cool and condense, preventing much of it from escaping with the breath.

CBecause the kangaroo rat does not drink water, it urinates less often, and it is thus able to retain much of the water it gets through other means.

DKangaroo rats get some water from their food by processing it efficiently and storing it in a moist environment.

EKangaroo rats have behavioral and physiological characteristics that limit the amount of water they lose through sweating and urination.

FKangaroo rats stay in burrows to take advantage of underground moisture, and when they come out they are able to physiologically process cached seeds more easily.