单选题According to the passage, what would happen to healthy cells within 48 hours of exposure to radio waves?AThe number of healthy cells will keep declining as more and more of them die.BThe number of healthy cells will initially drop before recovering rapidly.CThe number of healthy cells will be on steady increase throughout the process.DThe scientists have not yet arrived at any conclusion on this issue.
单选题
According to the passage, what would happen to healthy cells within 48 hours of exposure to radio waves?
A
The number of healthy cells will keep declining as more and more of them die.
B
The number of healthy cells will initially drop before recovering rapidly.
C
The number of healthy cells will be on steady increase throughout the process.
D
The scientists have not yet arrived at any conclusion on this issue.
参考解析
解析：
事实细节的找寻和判断。根据上题解析可知，暴露在无线电波之下24小时，被杀死的白血病细胞比正常细胞数量多出20%。但录音中同时指出“longer exposure to the radio waves triggered genes in the surviving cancer cells to divide aggressively”，可知若接受超过24小时（48小时）的连续辐射后，残余癌细胞中的基因会大量繁殖。但对于健康细胞的影响，有关科学家表示“We don’t know what the effects would be on healthy human cells”，由此可知，选项D与录音原文相符。
事实细节的找寻和判断。根据上题解析可知，暴露在无线电波之下24小时，被杀死的白血病细胞比正常细胞数量多出20%。但录音中同时指出“longer exposure to the radio waves triggered genes in the surviving cancer cells to divide aggressively”，可知若接受超过24小时（48小时）的连续辐射后，残余癌细胞中的基因会大量繁殖。但对于健康细胞的影响，有关科学家表示“We don’t know what the effects would be on healthy human cells”，由此可知，选项D与录音原文相符。
相关考题：
共用题干What Is Cancer?Cancer is actually a group of many related diseases that all have to do with cells.Cells are the very small units that make up all________(1)things,including the human body.There are billions of cells________(2)each person's body.Cancer happens when cells that are not normal grow________(3)spread veryfast.Normal body cells grow and divide and know when to stop growing.Over time,they also die._______(4)these normal cells,cancer cells just continue to grow and divide out of control and don't die.Cancer cells usually group together to form tumors（肿瘤）.A growing tumor becomes a lump of cancer cells_________(5)can destroy the normal cells around the_________(6)and damage the body's healthy tissues.Thiscan make someone very _______(7).Sometimes cancer cells break away from the original tumor and travel to other areas of the________(8),where they keep growing and can go on to form new tumors.This is how cancer__________(9).The spread of a tumor to a new place in the body is __________(10)metastasis（转移）.People with cancer may feel pretty sick at times一but can usually still do lots of normal things._________(11)they are very sick,kids and teenagers with cancer may still be able to go to school. They may be tired or bruise（出现青肿）easily, but they __________( 1 2) sometimes go to camp , movies , and sleepover（在外过夜的）parties. People with cancer still like the same things they did__________(13)they got sick.Cancer in kids is rare一but today,many kids who do get cancer go on living normal lives.The number of kids who beat cancer goes________(14)every year because of new cancer treatments.So a lot of kids with cancer will some day drive cars,go to college, have careers,and even get_________(15)and have families of their own._________(1) A:living B:nice C: big D: whole
共用题干LeukemiaLeukemia is the most common type of cancer kids get,but it is still very rare.Leukemia involves the blood and blood-forming organs,such as the bone marrow.________(46)A kid with leukemia produces lots of abnormal white blood cells in the bone marrow. Usually,white blood cells fight infection,but the white blood cells in a person with leukemia don't work the way they're supposed to.________(47)The abnormal white blood cells multiply out of control,filling the bone marrow and making it hard for enough normal,infection-fighting white blood cells to form.Other blood cells一such asred blood cells(that carry oxygen in the blood to the body's tissues)and platelets(that allow blood to clot）一are also crowded out by the white blood cells of leukemia. These cancer cells may also move to other parts of the body,including the bloodstream,where they continue to multiply and build up.Although leukemia can make kids sick,most of the time it is treatable,and kids get better. Almost all leukemia patients are treated with chemotherapy,which means using anti-cancer drug.________(48)Chemotherapy quickly goes to work,traveling through the blood to the bone marrow. There,the drugs can attack the cancer cells.After several weeks of chemotherapy,many kids begin to feel better.Some children with leukemia will also have to have radiation therapy,too.________(49)If the cancer isn't getting better from using the usual amounts of chemotherapy and radiation,then a kid with leukemia will probably need more treatment一with higher doses of chemotherapy and radiation to finally kill the cancer cells.But this heavy-duty treatment will also harm the normal cells in the kid's bone marrow too,and the bone marrow will no longer be able to produce normal blood cells.So,doctors will then give a kid一or anyone else with bone marrow that is no longer working一normal bone marrow tissue from someone else who is healthy.________(50)___________（48）A:The chemotherapy drugs are given through a catheter,a narrow tube that is inserted into a blood vessel, sometimes in the kid's upper chest.B:Early symptoms of leukemia are often overlooked,since they may resemble symptoms of the flu or other common diseases.C:This is a special procedure called a bone marrow transplant,and it helps the patient make new blood cells so they can recover from the leukemia.D:Bone marrow is the innermost part of some bones where blood cells are first made.E:They don't protect the person from infections very well.F: Radiation therapy uses invisible high-energy waves(similar to X-rays)to kill cancerous cells.
共用题干第三篇 Nuclear Power and Its DangerNqclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital or-gans.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.if the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones. But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce them-selves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done with-out the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine, then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can cause serious consequences even at the lowest level_________.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can________.A:kill large numbers of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.According to the passage,the danger of nuclear power lies in________.A:nuclear mysteryB:radiation detectionC:nuclear radiationD:radiation level
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共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can cause serious consequences even at the lowest level________.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation1 can cause serious consequences even at the lowest level______.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干第三篇 Nuclear Power and Its DangerNqclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital or-gans.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.if the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones. But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce them-selves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done with-out the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine, then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can_________.A:kill large numbers of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干第一篇Human Heart can Make New CellsSolving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues togenerate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows with age.The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart diseases such as heart failure and heart attack,experts say."We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with or whether they could be renewed,"he said."The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only 0.45 percent by age 75."If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for example,a heart attack,"Frisen said.That could lead to treatment that helps restore damaged hearts."A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the Karolinska Institute."Chronic heart failure arises from heart cells dying," he said."With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off,especially in older patients with heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一 whether the rate of cell turnover in diseased hearts is the same remains unknown.The human heart stops producing cardiac cells ______.A:when a person becomes oldB:as soon as a person gets sickC:immediately after a person is bornD:once a person dies
共用题干第二篇Bone Marrow TransplantationBone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.Before receiving healthy cells,diseased cells must_________.A:undergo chemotherapyB:go through radiationC:be preparedD:be wrecked
共用题干AIDSThe World Health Organization(WHO)says as many as 10 million persons worldwidemay have the virus that causes AIDS（艾滋病）.Experts believe about 350, 000 personshave the disease.And one million more may get it in the next five years. In the UnitedStates,about 50,000 persons have died with AIDS.The country's top medical official says more than 90 percent of all Americans who had the AIDS virus five years ago are dead.There is no cure for AIDS and no vaccine（疫苗）or medicine to prevent it. However, researchers know much more about AIDS than they did」ust a few years ago.We now know that AIDS is caused by a virus.The virus invades healthy cells,including white blood cellsthat are part of our defense system against disease.It takes control of the healthy cell's genetic material and forces the cell to make a copy of the virus.The cell then dies.And the virus-caused particles move on to invade and kill more healthy cells.The AIDS virus is carried in a person's body fluids.The virus can be passed sexually or by sharing instruments used to take intravenous（进入静脉的）drugs. It also can be passed in blood products or from a pregnant woman with AIDS to her developing baby.Many stories about the spread of AIDS are false.You cannot get AIDS by working or attending school with someone who has the disease.You cannot get it by touching drinking glasses or other objects used by such persons.Experts say no one has gotten AIDS by living with,caring for or touching an AIDS patient. According to the WHO,there are now 10 million AIDS patients in the world.A:Right B:Wrong C:Not mentioned
共用题干第一篇Human Heart can Make New CellsSolving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues togenerate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows with age.The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart diseases such as heart failure and heart attack,experts say."We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with or whether they could be renewed,"he said."The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only 0.45 percent by age 75."If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for example,a heart attack,"Frisen said.That could lead to treatment that helps restore damaged hearts."A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the Karolinska Institute."Chronic heart failure arises from heart cells dying," he said."With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off,especially in older patients with heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一 whether the rate of cell turnover in diseased hearts is the same remains unknown.Chronic heart failure is attributed to _________.A:the dying heart cellsB:the effect of pharmaceuticalsC:the weight of the patientD:the life span of a person
共用题干第二篇Bone Marrow TransplantationBone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.Healthy stem cells may come from the following sources EXCEPT__________.A:peripheral blood stem cellsB:baby bloodC:bone marrowD:cord blood
共用题干第二篇Bone Marrow TransplantationBone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.We can infer from this passage that_________.A:bone marrow transplantation requires five proceduresB:bone marrow transplantation is complexC:people with leukemia must need transplantationD:people with cancer must donate bone marrow before treatment
共用题干第二篇Bone Marrow TransplantationBone marrow is the spongy tissue inside some of your bones,such as your hip and thigh bones. It contains immature cells,called stem cells.The stem cells can develop into the red blood cells that carry oxygen through your body,the white blood cells that fight infections,and the platelets that help with blood clotting.If there is a problem with your bone marrow,a transplant can give you healthy new marrow. You could need a transplant because of a disease,such as bone marrow diseases or cancers like leukemia kemia or lymphoma.Or you might need one if a strong cancer treatment kills your healthy blood cells.People with cancer sometimes donate bone marrow before treatment to be transplanted later. But often the new marrow comes from a donor,either a close family member or someone unrelated.The healthy cells for a transplant can come from three sources:bone marrow;peripheral (circulating) blood that has an increased number of healthy blood-forming cells(also called peripheral blood stem cells or PBSC);umbilical cord blood that is collected after a baby is born.If you need an allogeneic transplant,your doctor will look for a marrow donor or cord blood unit that matches your HLA tissue type.HLA stands for human leukocyte antigen,a markei your immune system uses to recognize which cells belong in your body and which do not.Before your body can receive the healthy cells,the diseased cells must be destroyed.This is done using chemotherapy and sometimes radiation. The destruction of diseased cells is called a preparative regimen or a conditioning regimen.On the day of transplant,the cells from the marrow donor or cord blood unit are infused intravenously(go into your body through a large vein).These healthy cells move into the spaces inside your bones where they create new marrow. They grow and make healthy new red blood cells,white blood cells,and platelets.The new marrow usually comes from__________.A:people with cancerB:a family memberC:an organ donorD:a relative or a stranger
共用题干AIDSThe World Health Organization(WHO)says as many as 10 million persons worldwidemay have the virus that causes AIDS（艾滋病）.Experts believe about 350, 000 personshave the disease.And one million more may get it in the next five years. In the UnitedStates,about 50,000 persons have died with AIDS.The country's top medical official says more than 90 percent of all Americans who had the AIDS virus five years ago are dead.There is no cure for AIDS and no vaccine（疫苗）or medicine to prevent it. However, researchers know much more about AIDS than they did」ust a few years ago.We now know that AIDS is caused by a virus.The virus invades healthy cells,including white blood cellsthat are part of our defense system against disease.It takes control of the healthy cell's genetic material and forces the cell to make a copy of the virus.The cell then dies.And the virus-caused particles move on to invade and kill more healthy cells.The AIDS virus is carried in a person's body fluids.The virus can be passed sexually or by sharing instruments used to take intravenous（进入静脉的）drugs. It also can be passed in blood products or from a pregnant woman with AIDS to her developing baby.Many stories about the spread of AIDS are false.You cannot get AIDS by working or attending school with someone who has the disease.You cannot get it by touching drinking glasses or other objects used by such persons.Experts say no one has gotten AIDS by living with,caring for or touching an AIDS patient. America has the largest number of AIDS patients in the world.A:Right B:Wrong C:Not mentioned
共用题干第一篇Human Heart can Make New CellsSolving a longstanding（为时甚久的）mystery, scientists have found that the human heart continues togenerate new cardiac（心脏的）cells throughout the life span, although the rate of new cell production slows with age.The finding,published in the April 3rd issue of Science,could open a new path for the treatment of heart diseases such as heart failure and heart attack,experts say."We find that the beating cells in the heart, cardiomyocytes（心肌细胞）,are renewed," said lead researcher Dr. Jonas Frisen,a professor of stem cell research at the Karolinska Institute in Stockholm,Sweden."It has previously not been known whether we were limited to the cardiomyocytes we were born with or whether they could be renewed,"he said."The process of renewing these cells changes over time,"Frisen added. In a 20-year-old,about 1percent of cardiomyocytes are exchanged each year , but the turnover（更替）rate decreases with age to only 0.45 percent by age 75."If we can understand how the generation of new cardiomyocytes is regulated,it may be potentially possible to develop pharmaceuticals（药物）that promote this process to stimulate regeneration after , for example,a heart attack,"Frisen said.That could lead to treatment that helps restore damaged hearts."A lot of people suffer from chronic heart failure,."noted co-author Dr. Ratan Bhardwaj,also from the Karolinska Institute."Chronic heart failure arises from heart cells dying," he said."With this finding,scientists are opening the door to potential therapies（疗法）,to having ourselves heal ourselves,"Bhardwaj said."Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."But barriers remain.According to Bhardwaj,scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off,especially in older patients with heart failure.In addition,the number of new cells the heart produces was estimated using healthy hearts一 whether the rate of cell turnover in diseased hearts is the same remains unknown.It is not known yet if the rate of cell turnover in diseased hearts_________.A:is high enough to replace cells faster than they're dying offB:is of any use to researchersC:is the same as that in healthy heartsD:changes over time
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can_______.A:kill large number of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干AgingThroughout history man has had to accept the fact that all living things must die,but people now live longer than they used to.Yet all living things still show the________(51)of aging,which will eventually________(52)death.Aging is not a disease,but as a person passes maturity,the cells of the body and the________ (53) do not function as well as they did in childhood and adolescence（青春期）.The body provides less________(54)against disease and is more likely________(55)have accident.A number of related causes may________(56)aging. Some cells of the body have a fairly long life,but they are not reborn when they die.As a person ages,________(57)of brain cells and muscle cells decreases.The other cells are replaced by new cells.In an aging person the________(58) cells and muscle cells may not be as viable（能生存的）or as capable________ ( 59 ) growth as those of a young person.Another________(60)in aging may be changes within the cells themselves.Some of the protein chemicals in cells are known________(61)with age and became less elastic.This is why the skin of old people wrinkles and________(62).This is also the reason old people________(63)in height. There may not be other more important chemical changes in the cells.Some complex cell chemicals, such as DNA and RNA,store and________(64)information that the cells need.Aging may affect this________(65)and change the information-carry molecules so that they do not transmit the information as well._________(51)A:function B:effectC:fact D:symbol
共用题干AgingThroughout history man has had to accept the fact that all living things must die,but people now live longer than they used to.Yet all living things still show the________(51)of aging,which will eventually________(52)death.Aging is not a disease,but as a person passes maturity,the cells of the body and the________ (53) do not function as well as they did in childhood and adolescence（青春期）.The body provides less________(54)against disease and is more likely________(55)have accident.A number of related causes may________(56)aging. Some cells of the body have a fairly long life,but they are not reborn when they die.As a person ages,________(57)of brain cells and muscle cells decreases.The other cells are replaced by new cells.In an aging person the________(58) cells and muscle cells may not be as viable（能生存的）or as capable________ ( 59 ) growth as those of a young person.Another________(60)in aging may be changes within the cells themselves.Some of the protein chemicals in cells are known________(61)with age and became less elastic.This is why the skin of old people wrinkles and________(62).This is also the reason old people________(63)in height. There may not be other more important chemical changes in the cells.Some complex cell chemicals, such as DNA and RNA,store and________(64)information that the cells need.Aging may affect this________(65)and change the information-carry molecules so that they do not transmit the information as well._________(56)A:concern B:contribute toC:happen to D:bring to
单选题What is the speaker’s main topic?AEffects of using mobile phones on healthy human cells.BRisks of developing cancer involved in the use of mobile phones.CDamage to healthy cells caused by the use of mobile phones.DThe potential health hazards of mobile phones on humans.
单选题According to the passage, what would happen to healthy cells within 48 hours of exposure to radio waves?AThe number of healthy cells will keep declining as more and more of them die.BThe number of healthy cells will initially drop before recovering rapidly.CThe number of healthy cells will be on steady increase throughout the process.DThe scientists have not yet arrived at any conclusion on this issue.
单选题Supposing 1 million leukemia cells were killed after 24 hours of exposure to radio waves, how many healthy cells would be killed under the same condition?A1.2 million.B1.4 million.C0.8 million.D2 million.
单选题Which of the following is NOT TRUE according to the passage?AWe will be in trouble if our fat cells become less responsive to insulin.BMore and more studies are done to study the link between sleep and weight.CMore than 20％ of Americans are not getting enough sleep.DFat cells are there to help us maintain a good health.
单选题Which of the following is an appropriate title for this passage?APoor Sleep May Lead to Too Much Stored Fat and DiseaseBSleep Experts Had Exciting Findings in a Fat StudyCAmericans Should Have More Than Six Hours of SleepDBad Things Happen if Fat Cells Become Our Friend
单选题According to the passage, what did Darwin believe would happen to human emotions that were not expressed?AThey would become less intense.BThey would last longer than usual.CThey would cause problems later.DThey would become more negative.