大学四级-1092及答案解析.doc

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1、大学四级-1092 及答案解析(总分：713.00，做题时间：90 分钟)一、Part Writing(总题数：1，分数：106.00)1.锻炼身体和平衡饮食哪个是保持健康的最佳办法2我的观点（分数：106.00）_二、Part Reading Compr(总题数：4，分数：70.00)How Exercises WorkWhen you exercise or compete in sports, you notice several things about your body. You breathe heavier and faster, your heart beats faster

2、, your muscles hurt and you sweat. These are all normal responses to exercise whether you work out regularly or only once in a while or whether you are a “weekend warrior“ or a trained athlete. When you watch world-class athletes compete, you see the same responses, only magnified.The body has an in

3、credibly complex set of processes to meet the demands of working muscles. Every system in the body is involved. In this article, we will look at how your body responds to strenuous exercise-how muscles, blood circulation, breathing and body heat are affected. You will also see how these responses ca

4、n be enhanced by training. Your Bodys Response to ExerciseAny type of exercise uses your muscles. Running, swimming, weighttiftingany sport you can imagineuses different muscle groups to generate motion. In running and swimming, your muscles are working to accelerate your body and keep it moving. In

5、 weightlifting, your muscles are working to move a weight. Exercise means muscle activity!As you use your muscles, they begin to make demands on the rest of the body. In strenuous exercise, just about every system in your body either focuses its efforts on helping the muscles do their work, or it sh

6、uts down. For example, your heart beats faster during strenuous exercise so that it can pump more blood to the muscles, and your stomach shuts down during strenuous exercise so that it does not waste energy that the muscles can use.When you exercise, your muscles act something like electric motors.

7、Your muscles take in a source of energy and they use it to generate force. An electric motor uses electricity to supply its energy. Your muscles are biochemical motors, and they use a chemical called adenosine triphosphate ( ATP ) for their energy source. During the process of “burning“ ATP, your mu

8、scles need three things:They need oxygen, because chemical reactions require ATP and oxygen is consumed to produce ATP.They need to eliminate metabolic wastes (carbon dioxide, lactic acid ) that the chemical reactions generate.They need to get rid of heat. Just like an electric motor, a working musc

9、le generates heat that it needs to get rid of.In order to continue exercising, your muscles must continuously make ATP. To make this happen, your body must supply oxygen to the muscles and eliminate the waste products and heat. The more strenuous the exercise, the greater the demands of working musc

10、le. If these needs are not met, then exercise will cease-that is, you become exhausted and you wont be able to keep going.To meet the needs of working muscle, the body has an orchestrated response involving the heart, blood vessels, nervous system, lungs, liver and skin. It really is an amazing syst

11、em!Exercise and ATPFor your musclesin fact, for every cell in your bodythe source of energy that keeps everything going is called ATP. Adenc, sine triphosphate (ATP) is the biochemical way to store and use energy.The entire reaction that turns ATP into energy is a bit complicated, but here is a good

12、 summary:Chemically, ATP is an adenine nucleotide bound to three phosphates.There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions.When a cell needs energy, it breaks this bond to form adenosine diphosphate (ADP) and a fr

13、ee phosphate molecule.In some instances, the second phosphate group can also be broken to form adenosine monophosphate (AMP).When the cell has excess energy, it stores this energy by forming ATP from ADP and phosphate.ATP is required for the biochemical reactions involved in any muscle contraction.

14、As the work of the muscle increases, more and more ATP gets consumed and must be replaced in order for the muscle to keep moving.Because ATP is so important, the body has several different systems to create ATP. These systems work together in phases. The interesting thing is that different forms of

15、exercise use different systems, so a sprinter is getting ATP in a completely different way from a marathon runner!ATP comes from three different biochemical systems in the muscle, in this order:phosphagen systemglycogen-lactic acid systemaerobic respirationExercise and the Phospbagen SystemA muscle

16、cell has some amount of ATP floating around that it can use immediately, but not very muchonly enough to last for about three seconds. To replenish the ATP levels quickly, muscle cells contain a high-energy phosphate compound called creatine phosphate. The phosphate group is removed from creatine ph

17、osphate by an enzyme called creatine kinase, and is transferred to ADP to form ATP. The cell turns ATP into ADP, and the phosphagen rapidly turns the ADP back into ATP. As the muscle continues to work, the creatine phosphate levels begin to decrease. Together, the ATP levels and creatine phosphate l

18、evels are called the phosphagen system. The phosphagen system can supply the energy needs of working muscle at a high rate, but only for 8 to 10 seconds. Exercise and the Glycogen-Lactic Acid SystemMuscles also have big reserves of a complex carbohydrate called glycogen. Glycogen is a chain of gluco

19、se molecules. A cell splits glycogen into glucose. Then the cell uses anaerobic metabolism (anaerobic means “without oxygen“) to make ATP and a byproduct called lactic acid from the glucose.About 12 chemical reactions take place to make ATP under this process, so it supplies ATP at a slower rate tha

20、n the phosphagen system. The system can still act rapidly and produce enough ATP to last about 90 seconds. This system does not need oxygen, which is handy because it takes the heart and lungs some time to get their act together. It is also handy because the rapidly contracting muscle squeezes off i

21、ts own blood vessels, depriving itself of oxygen-rich blood.There is a definite limit to anerobic respiration because of the lactic acid. The acid is what makes your muscles hurt. Lactic acid builds up in the muscle tissue and causes the fatigue and soreness you feel in your exercising muscles.Exere

22、ise and Aerobic RespirationBy two minutes of exercise, the body responds to supply working muscles with oxygen. When oxygen is present, glucose can be completely broken down into carbon dioxide and water in a process called aerobic respiration. The glucose can come from thee different places:remaini

23、ng glycogen supplies in the muscles;breakdown of the livers glycogen into glucose, which gets to working muscle through the bloodstream;absorption of glucose from food in the intestine, which gets to working muscle through the bloodstream.Aerobic respiration can also use fatty acids from fat reserve

24、s in muscle and the body to produce ATP. In extreme cases (like starvation), proteins can also be broken down into amino acids and used to make ATP. Aerobic respiration would use carbohydrates first, then fats and finally proteins, if necessary. Aerobic respiration takes even more chemical reactions

25、 to produce ATP than eitherofthe above systems. Aerobic respiration produces ATP at the slowest rate of the three systems, but it can continue to supply ATP for several hours or longer, so long as the fuel supply lasts.What Happens When You ExerciseSo imagine that you start running. Heres what happe

26、ns:The muscle cells burn off the ATP they have floating around in about 3 seconds.The phosphagen system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid acceleration, short-duration exerc

27、ise occurs.If exercise continues longer, then the glycogen-lactic acid system kicks in. This would be true for short-distance exercises such as a 200-or 400-meter dash or 100-meter swim.Finally, if exercise continues, then aerobic respiration takes over. This would occur in endurance events such as

28、an 800- meter dash, marathon run, rowing, cross-country skiing and distance skating.When you start to look closely at how the human body works, it is truly an amazing machine!（分数：49.00）(1).Your muscles are working to move a weight when you are_.（分数：7.00）A.swimmingB.weightliffingC.runningD.high jumpi

29、ng(2).During the process of “burning“ ATP, your muscles need_.（分数：7.00）A.to eliminate heatB.lactic acidC.carbon dioxideD.to add energy(3).When the cell has excess energy, it stores this energy by forming_.（分数：7.00）A.phosphateB.AMPC.ADPD.ATP(4).The body has several different systems to create_, becau

30、se it is very important.（分数：7.00）A.AMPB.ADPC.ATPD.phosphate molecule(5).Muscle cells contain a high-energy phosphate compound called_.（分数：7.00）A.creatine kinaseB.creatine phosphateC.phosphate groupD.enzyme(6).What makes your muscles hurt?（分数：7.00）A.Glucose.B.ATP.C.Oxygen-rich blood.D.Lactic acid.(7)

31、.Glucose can be completely broken down into carbon dioxide and water when oxygen is present in the process called_.（分数：7.00）A.anaerobic metabolismB.“burning“ ATPC.aerobic respirationD.phosphagen system2.When you are starving，proteins can also be broken down into 1.（分数：7.00）填空项 1:_3.When you start ru

32、nning，the muscle cells bum off the ATP they have floating around in 1.（分数：7.00）填空项 1:_4.Aerobic respiration would occur in 1.（分数：7.00）填空项 1:_三、Part Listening Com(总题数：0，分数：0.00)四、Section A(总题数：4，分数：105.00)Directions: In this section, you will hear 8 short conversations and 2 long conversations. At th

33、e end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer

34、. Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre.（分数：35.00）A.Aholiday.B.Luck.C.Work.D.An accident.A.She prefers the stadium.B.She agrees with the man.C.The light isnt bright enough.D.The dining hall isnt large enough.A.Two hours by train.B.One hour by trai

35、n.C.One hour by bus.D.One hour by car.A.English.B.Canadian.C.Australian.D.Austrian.A.Straight ahead on the street.B.On the right.C.On the left.D.Over there.Questions 19 to 22 are based on the conversation you have just heard.（分数：28.00）A.She generally doesnt allow people to borrow it.B.She is trying

36、to sell it.C.She bought it from a friend.D.It has broken down before.A.The woman could probably repay it herself.B.Its rather small.C.It probably wont cost a lot to repair.D.Its probably difficult to drive.A.He only works on new cars.B.He has fixed her car before.C.He is one of her neighbors.D.He wi

37、ll probably overcharge her.A.Take the woman to her home.B.Test-drive the womans car.C.Help the woman pay the mechanics bill.D.Help the woman fix her car.Questions 23 to 25 are based on the conversation you have just heard.（分数：21.00）A.The possible existence of life on other planets.B.Methods for buil

38、ding powerful new telescopes.C.A technical problem that astronomers cant solve.D.The discovery of planets orbiting distant stars.A.They studied variations in the appearance of the parent stars.B.They were able to see the planets with a telescope.C.They compared the parent stars to the Sun.D.They sen

39、t astronauts on a mission into space.A.Their surface features.B.Their chemical composition.C.Their temperature.D.Their age.A.B.C.D.A.B.C.D.A.B.C.D.五、Section B(总题数：3，分数：70.00)Questions 26 to 28 are based on the passage you have just heard.（分数：21.00）A.She does her shopping.B.She drinks extra tea.C.She

40、 eats a lot of things.D.She sleeps a great deal.A.Problems with the teachers.B.Problems with family members or friends.C.Problems with class work.D.Problems with a part-time job.A.Talking to someone over the phone.B.Drinking some diet coke.C.Playing a video game.D.Drinking extra tea.Questions 29 to

41、31 are based on the passage you have just heard,（分数：21.00）A.They were able to fly it in the air.B.They were able to stay up in the air for half an hour and more in the machine.C.They were able to carry travelers.D.They were able to fly in around Dayton.A.Nothing.B.A lot.C.Hardly anything.D.a little.

42、A.The reporters didnt believe what people told them about the flights.B.The Government didnt give the Wrights any money.C.The Government thought the Wrights wanted money in order to build an airplane.D.At the time it seemed no one could understand them.Questions 32 to 35 are based on the passage you

43、 have just heard.（分数：28.00）A.The writer enjoys sleeping very much.B.The writer doesnt like money at all.C.Bill Gates does not koow how to enjoy himself.D.Mental well-being is the most important thing.A.Material life.B.Sports life.C.Spiritual life.D.Working life.A.It is very commercial.B.It is very n

44、oisy.C.It is very insecure.D.It is very unfriendly.A.Importance of A Good Nights SleepB.The Best Things Money Cannot BuyC.Taking Good Care of OneselfD.How to Enjoy Life Thoroughly六、Section C(总题数：1，分数：77.00)A new book is sure to be discussed，and (36) ，at colleges this fallThe book is called My Freshm

45、an Year What a Professor Learned by Becoming a StudentThe writer is Rebekah NathanThat is not her real nameShe is in her fiftiesShe is a professorof (37) at a universityintheUnited StatesHernameforitis“AnyU”The professor wanted to know why many ofher students did not (38) their work or ask for helpS

46、he decided to do a (39) projectShe got the (40) ofthe university ethics (41) Such groups consider moral and legal issues in studiesIn the spring of 2002，she (42) to her own university under the name“Rebekah Nathan”and was admittedShe lived in student housingShe took five classes during her first ter

47、m and two in the second (43) She did pretty well， although she got one C，a mark ofaverageShe also played sports(44) .(45) .They are busy with activities and jobsThey try to learn only as much as they have toBut she says they will read the material if it is directly linked to what is being discussed

48、in class，(46)_.（分数：77.00）(1).A new book is sure to be discussed，and (36) ，at colleges this fallThe book is called My Freshman Year What a Professor Learned by Becoming a StudentThe writer is Rebekah NathanThat is not her real nameShe is in her fiftiesShe is a professorof (37) at a universityintheUni

49、ted StatesHernameforitis“AnyU”The professor wanted to know why many ofher students did not (38) their work or ask for helpShe decided to do a (39) projectShe got the (40) ofthe university ethics (41) Such groups consider moral and legal issues in studiesIn the spring of 2002，she (42) to her own university under the name“Rebekah Nathan”and was admittedShe lived i