托福听力tpo46lecture1、2、3、4原文+题目+答案+译文Lecture1 (2)原文 (2)题目 (4)答案 (6)译文 (6)Lecture2 (8)原文 (8)题目 (10)答案 (12)译文 (12)Lecture3 (14)原文 (14)题目 (16)答案 (18)译文 (18)Lecture4 (19)原文 (19)题目 (22)答案 (24)译文 (24)Lecture1原文NARRATOR:Listen to part of a lecture in a biology class.FEMALE PROFESSOR:I'd like to continue our discussion of animal behavior and start off today's class by focusing on a concept we haven't yet touched upon—swarm intelligence.Swarm intelligence is a collective behavior that emerges from a group of animals,like a colony of termites,a school of fish,or a flock of birds.Let's first consider the principles behind swarm intelligence,and we'll use the ant as our model.Now,an ant on its own is not that smart.When you have a group of ants,however, there you have efficiency in action.You see,there's no leader running an ant colony. Each individual,each individual ant operates by instinctively following a simple set of rules when foraging for food.Rule number1:Deposit a chemical marker…called a pheromone.And rule2:Follow the strongest pheromone path.The strongest pheromone path is advantageous to ants seeking food.So,for example,when ants leave the nest,they deposit a pheromone trail along the route they take.If they find food,they return to the nest on the same path and the pheromone trail gets stronger—it's doubled in strength.Because an ant that took a shorter path returns first,its pheromone trail is stronger,and other ants will follow it, according to rule2.And as more ants travel that path,the pheromone trail gets even stronger.So,what's happening here?Each ant follows two very basic rules,and each ant acts on information it finds in its immediate local environment.And it's important to note: Even though none of the individual ants is aware of the bigger plan,they collectively choose the shortest path between the nest and a food source because it's the most reinforced path.By the way,a-a few of you have asked me about the relevance of what we're studying to everyday life.And swarm intelligence offers several good examples of how concepts in biology can be applied to other fields.Well,businesses have been able to use this approach of following simple rules when designing complex systems,for instance,in telephone networks.When a call is placed from one city to another,it has to connect through a number of nodes along the way.At each point,a decision has to be made:Which direction does the call go from here?Well,a computer program was developed to answer this question based on rules that are similar to the ones that ants use to find food.Remember,individual ants deposit pheromones,and they follow the path that is most reinforced.Now,in the phone network,a computer monitors the connection speed of each path, and identifies the paths that are currently the fastest—the least crowded parts of the network.And this information,converted into a numeric code,is deposited at the network nodes.This reinforces the paths that are least crowded at the moment. The rule the telephone network follows is to always select the path that is most reinforced.So,similar to the ant's behavior,at each intermediate node,the call follows the path that is most reinforced.This leads to an outcome which is beneficial to the network as a whole,and calls get through faster.But getting back to animal behavior,another example of swarm intelligence is the way flocks of birds are able to fly together so cohesively.How do they coordinate their movements and know where they're supposed to be?Well,it basically boils down to three rules that each bird seems to follow.Rule1:Stay close to nearby birds.Rule2:Avoid collision with nearby birds.And rule3:Move in the average speed and direction of nearby birds.Oh,and by the way,if you're wondering how this approach can be of practical use for humans:The movie industry had been trying to create computer-generated flocks of birds in movie scenes.The question was how to do it easily on a large scale?A researcher used these threerules in a computer graphics program,and it worked!There have also been attempts to create computer-generated crowds of people using this bird flocking model of swarm intelligence.However,I'm not surprised that more research is needed.The three rules I mentioned might be great for bird simulations,but they don't take into account the complexity and unpredictability of human behavior.So,if you want to create crowds of people in a realistic way,that computer model might be too limited.题目1.What is the lecture mainly about?A.Various methods that ants use to locate foodB.A collective behavior common to humans and animalsC.A type of animal behavior and its application by humansD.Strategies that flocks of birds use to stay in formation2.According to the professor,what behavior plays an important role in the way ants obtain food?A.Ants usually take a different path when they return to their nest.B.Ants leave chemical trails when they are outside the nest.C.Small groups of ants search in different locations.D.Ants leave pieces of food along the path as markers.3.What are two principles of swarm intelligence based on the ant example?[Click on2answers.]A.Individuals are aware of the group goal.B.Individuals act on information in their local environment.C.Individuals follow a leader's guidance.D.Individuals instinctively follow a set of rules.4.According to the professor,what path is followed by both telephone calls on a network and ants seeking food?A.The path with the least amount of activityB.The most crowded pathC.The path that is most reinforcedD.The path that has intermediate stopping points5.Why does the professor mention movies?A.To identify movie scenes with computer-simulated flocks of birdsB.To identify a good source of information about swarm intelligenceC.To emphasize how difficult it still is to simulate bird flightD.To explain that some special effects in movies are based on swarm intelligence6.What is the professor's attitude about attempts to create computer-generated crowds of people?A.She believes that the rules of birds'flocking behavior do not apply to group behavior in humans.B.She thinks that crowd scenes could be improved by using the behavior of ant colonies as a model.C.She is surprised by how realistic the computer-generated crowds are.D.She is impressed that computer graphics can create such a wide range of emotions.答案C B BD C D A译文下面听一段生物学讲座的片段。
托福听力tpo39lecture1、2、3、4原文+题目+答案+译文Lecture1 (2)原文 (2)题目 (4)答案 (6)译文 (6)Lecture2 (8)原文 (8)题目 (10)答案 (12)译文 (12)Lecture3 (14)原文 (14)题目 (16)答案 (18)译文 (18)Lecture4 (19)原文 (19)题目 (22)答案 (23)译文 (24)Lecture1原文NARRATOR:Listen to part of a lecture in a geology class.MALE PROFESSOR:Since Earth formed,some four and a half billion years ago,the number of minerals here has increased dramatically,from a few dozen relatively simple minerals early on…to over4,300kinds of minerals we can identify today—many of them wonderfully complex.A basic question of geology is how all these new minerals came into being.Well,recent studies have turned to biology to try to explain how this happens.Now,much of biology is studied through the lens of evolution.And the theory of evolution suggests that,as environments change—and inevitably they do—some organisms will have characteristics that allow them to adapt to those changes successfully…characteristics that help these organisms develop and survive and reproduce.And when environments become more complex—as tends to happen over time—those earlier adaptations,those variations…become the basis of yet other combinations and variations…and lead to ever more diverse and complex forms of life.So from fewer,simpler,and relatively similar forms of life billions of years ago,life on Earth has now become a dazzling array of diversity and complexity.Well,some geologists now want to apply this concept to explain mineral diversity too. The conditions that minerals are under are not constant.Conditions like temperature or pressure or chemical surroundings—these change—often in cycles,increasing and decreasing slowly over time.And as conditions change,minerals sometimes break down and their atoms recombine into totally new compounds,as part of a process some call mineral evolution.Now,minerals are not alive,of course,so this is not evolution in quite the same sense you'd have in living organisms.But there do appear to be some parallels.Living organisms not only adapt to their environment but also affect it—change theenvironment within which other organisms may then develop.Likewise,each new mineral also enriches the chemical environment from which lots of other,even more complex new minerals may be formed in the future.Beyond these similarities,though,what's really fascinating about mineral evolution is the way minerals apparently coevolve with living organisms.Uh,what do I mean by that?Well,it's maybe a billion years after Earth’s formation that we first see evidence of life.Of course,early life-forms were primitive—just tiny,single-celled microbes—but over time,they had a profound effect.Huge numbers of these microbes began producing food by photosynthesis,which,of course,also freed up enormous amounts of oxygen.And lots of that oxygen interacted with the atoms of existing minerals,creating rust out of iron,for instance,…reacting with a whole range of different metals to create lots of new minerals.Now,living organisms rely on minerals.But they not only take in some minerals as nutrients,they also excrete others as waste products...including what we call biominerals—minerals that form with the help of biological life.We can see geologic evidence of biomineral production in what are called stromatolites.Stromatolites look like wavy layers of sedimentary rock.But they're really fossils—fossils of the waste from microbial mats.Microbial mats are vast colonies of one-celled organisms…that were once the most prevalent form of life on Earth.And the study of stromatolites indicates that these ancient microbial mats interacted with minerals in the environment and left behind new compounds as waste products—biominerals like carbonates,phosphates,and silica.In fact,we’ve grown microbial mats in the laboratory,and,over time,they too have produced some of the same sorts of minerals found in stromatolites.Uh,you don't need to know the details of the process right now—we’re still figuring out just how it works,ourselves.But you might be interested to know that this concept of mineral evolution is being used in the search for evidence of life on other planets.The thinking is that if certainminerals occur here on Earth as a result of a biological process,and if we also find those same minerals on another planet,…this would suggest that life may have once existed there.But—just because a particular mineral is found on say,Mars or Venus—uh,we really shouldn't assume that whatever caused it to turn up there…must be the same process that formed that mineral here on Earth.题目1.What is the main purpose of the lecture?A.To explain how geologists identified the minerals present during Earth's formation.B.To explain why living organisms require certain minerals to survive.C.To explain the differences between simple and compound minerals.D.To explain a recent theory about mineral formation.2.What point does the professor make about the minerals present during Earth's formation?A.They were comparatively few of them.B.They were more complex than minerals formed on other planets.C.Most were not affected by temperature and pressure changes on early Earth.D.Some of them are no longer being formed naturally on Earth.3.What similarities does the professor point out between minerals and living organisms?[Click on2answers.]A.Both first appeared on Earth at approximately the same time.B.They both can be formed only in the presence of oxygen.C.They both have become more diverse and complex over time.D.Not only are they both shaped by their environment,but both also affect it.4.What are stromatolites?A.Fossils remains of microbial mats.yered deposits of iron-based minerals.yers of rock that indicate changes in Earth's pressure and temperature.D.Rock formations created when oxygen interacts with certain metals.5.Why does the professor talk about microbial mats?A.To explain why organisms tend to colonize near certain minerals.B.To describe how minerals can be created by living organisms.C.To illustrate the effects of geological processes on living organisms.D.To emphasize that evolving life depended on the presence of oxygen.6.What does the professor think about using evidence of minerals on another planet to determine whether life has existed there?A.He believes it is the most promising way to search for life on another planet.B.He doubts that complex minerals will ever be found on another planet.C.He is cautious about assuming that certain minerals indicate the presence of life.D.He is surprised that the technique was not suggested until recently.答案D A CD A B C译文旁白：请听一段地质学讲座的节选片段。
托福听力tpo51lecture1、2、3、4原文+题目+答案+译文Lecture1 (1)原文 (1)题目 (3)答案 (5)译文 (6)Lecture2 (7)原文 (7)题目 (10)答案 (12)译文 (12)Lecture3 (14)原文 (14)题目 (16)答案 (18)译文 (18)Lecture4 (20)原文 (20)题目 (22)答案 (24)译文 (24)Lecture1原文NARRATOR:Listen to part of a lecture in a botany class.FEMALE PROFESSOR:So,continuing with crop domestication,and corn—or,um, maize,as it's often called.Obviously it's one of the world's most important cropstoday.It's such a big part of the diet in so many countries,and it's got so many different uses,that it's hard to imagine a world without it.But because it doesn't grow naturally,without human cultivation,and because there's no obvious wild relative of maize…uh,well,for the longest time,researchers weren’t able to find any clear link between maize and other living plants.And that's made it hard for them to trace the history of maize.Now,scientific theories about the origins of maize first started coming out in the 1930s.One involved a plant called teosinte.Teosinte is a tall grass that grows wild in certain parts of Mexico and Guatemala.When researchers first started looking at wild teosinte plants,they thought there was a chance that the two plants—um, maize and teosinte—were related.The young wild teosinte plant looks a lot like the corn plant,and the plants continue to resemble each other—at least superficially—even when they're developed.But when the scientists examined the fruits of the two plants,it was a different story. When you look at ripe corn,you see row upon row of juicy kernels…um,all those tiny little yellow squares that people eat.Fully grown teosinte,on the other hand, has a skinny stalk that holds only a dozen or so kernels behind a hard,um,almost stonelike casing.In fact,based on the appearance of its fruit,teosinte was initially considered to be a closer relative to rice than to maize.But there was one geneticist,named George Beadle,who didn't give up so easily on the idea that teosinte might be…well…the“parent”of corn.While still a student in the1930s,Beadle actually found that the two plants had very similar chromosomes—very similar genetic information.In fact,he was even able to make fertile hybrids between the two plants.In hybridization,you remember,the genes of two species of plants are mixed to produce a new,third plant—a hybrid.And if this offspring—this hybrid—is fertile,then that suggests that the two species are closely related genetically.This new,hybrid plant looked like an intermediate,right between maize and teosinte.So,Beadle concluded that maize must've been developed over many years,uh,that it is a domesticated form of teosinte.Many experts in thescientific community,however,remained unconvinced by his conclusions.They believed that,with so many apparent differences between the two plants,it would have been unlikely that ancient—that prehistoric peoples could’ve domesticated maize from teosinte.I mean,when you think about it,these people lived in small groups,and they had to be on the move constantly as the seasons changed.So for them to selectively breed,to have the patience to be able to pick out just the right plants…and gradually—over generations—separate out the durable,nutritious maize plant from the brittle teosinte that easily broke apart…it's a pretty impressive feat,and you can easily see why so many experts would have been skeptical.But,as it turns out,Beadle found even more evidence for his theory when he continued his experiments,producing new hybrids,to investigate the genetic relationship between teosinte and maize.Through these successive experiments,he calculated that only about five specific genes were responsible for the main differences between teosinte and maize—the plants were otherwise surprisingly similar genetically.And more recently,botanists have used modern DNA testing to scan plant samples collected from throughout the Western Hemisphere.This has allowed them to pinpoint where the domestication of maize most likely took place—and their research took them to a particular river valley in southern Mexico.They've also been able to estimate that the domestication of maize most likely occurred about9,000 years ago.And subsequent archaeological digs have confirmed this estimate.In one site,archaeologists uncovered a set of tools that were nearly9,000years old.And these tools were covered with a dusty residue…a residue of maize,as it turns out…thus making them the oldest physical evidence of maize that we've found so far.题目1.What is the lecture mainly about?A.A research study that compares wild and domesticated plantsB.Problems with a commonly held hypothesis about the origin of teosinteC.Reasons why wild plants are usually unsuitable for agricultureD.The process used to identify the ancestor of a modern crop2.What evidence seemed to indicate that maize and teosinte are not related?A.Young teosinte plants do not physically resemble young maize plants.B.Preliminary DNA evidence indicated that teosinte was related to rice.C.Maize and teosinte usually grow in significantly different climates.D.Maize and teosinte have very different types of kernels.3.Why does the professor discuss hybrids?A.To explain how a geneticist confirmed that maize was widely grown9,000years agoB.To indicate the earliest method used by geneticists to identify plant originsC.To explain a method used to demonstrate a link between two plant speciesD.To describe how geneticists distinguish between wild plants and domesticated plants4.What was most researchers'initial view of George Beadle's theory about teosinte?A.They accepted it but questioned the evidence cited.B.They rejected it because of conflicting archaeological evidence.C.They questioned it because it implies that ancient farmers were sophisticatedplant breeders.D.They questioned it because genetic research was viewed with skepticism at that time.5.What did Beadle conclude about maize and teosinte?A.Both plants lack particular genes that are common in most domesticated plants.B.Both plants have particular genes that enable them to adapt to varying climates.C.Only a small number of genes are responsible for the differences between the two plants.D.The genetic composition of both plants is very similar to that of rice.6.According to the professor,why was the discovery of stone tools important?A.It proved that teosinte was simultaneously domesticated in multiple locations.B.It helped to confirm the period in which maize was first domesticated.C.It suggested that maize required farming techniques that were more complex than experts had previously assumed.D.It provided evidence that maize plants were used for more purposes than experts had previously assumed.答案D D C C C B译文旁白：请听一段植物学讲座的节选。
