Relationships Among Species托福聽力原文翻譯及問題答案

Relationships Among Species托福聽力原文翻譯及問題答案

一、Relationships Among Species托福聽力原文：

NARRATOR:Listen to part of a lecture in a biology class.MALE STUDENT:Professor,since we are going to talk about changes in animal populations in the wild,I'd like to ask about something I read in an article online,about how the population size of some animal species can affect other animal species,and how other environmental factors come into play too.FEMALE PROFESSOR:Right.Relationships between animal species in a given ecosystem can get pretty complex.Because in addition to predator-prey relationships,there are other variables that affect population size.MALE STUDENT:The article mentioned that populations of predators and their prey might go up rapidly and then decline all of a sudden.FEMALE STUDENT:Oh.Yeah!I read about that in my ecology class.It happens in cycles.I think that's called a boom-and-bust cycle.Right?FEMALE PROFESSOR:OK.Well,hold on a second.First I want to go over some key concepts.Let's say there was a species that had access to plenty of food and ideal conditions.Under those circumstances,its population would increase exponentially,meaning it would increase at an ever-accelerating pace.MALE STUDENT:Wow!That sounds a little scary.FEMALE PROFESSOR:Well,it doesn't usually happen.Like you said,a rapid population growth is often followed by a sudden decline.But we do occasionally see exponential growth in nonnative species when they are transplanted into a new environment.Um,because they face little competition and have favorable growing conditions.But for most species,most of the time,resources are finite.There's only so much available—which leads me to my point.Every ecosystem has what we call a carrying capacity.The carrying capacity is the maximum population size of a species that can be sustained by the resources of a particular ecosystem....Resources are,of course,food,water,and just as important,space.Although every species has a maximum rate at which the population of that species could increase,assuming ideal conditions for the species in its environment.There are always going to be environmental factors that limit population growth.This is called environmental resistance.Environmental resistance is important because it stops populations from growing out of control.Factors such food supply,predation and disease affect population size,and can change from year to year or season to season.MALE STUDENT:OK.I think I get it.FEMALE PROFESSOR:Well,let's look at a case study.That should make things clear.Some years ago,some of my colleagues conducted an experiment in an oak forest involving three different species:white-footed mice,gypsy moths and oak trees.OK.Now let me explain what the situation is in this forest.Oak trees produce acorns,and acorns are a primary food source for white-footed mice.Another food source for the white-footed mice is the gypsy moth.So the size of the gypsy moth population is controlled by the white-footed mice,which is a good thing because gypsy moth caterpillars are considered pests.They strip away the leaves from the oak trees every ten years or so.MALE STUDENT:So the mice eat both acorns from the oak trees and gypsy moths.And the gypsy moth caterpillars eat oak tree leaves.FEMALE PROFESSOR:Right.Now,what makes this set of relationships particularly interesting is that oak trees only produce a large number of acorns once every few years.MALE STUDENT:So during the years with fewer acorns,the white-footed mice have to deal with a smaller food supply.FEMALE PROFESSOR:Yes.But in the years with large amounts of acorns,the mice have more food,which leads to?MALE STUDENT:The white-footed mice population growing.FEMALE PROFESSOR:And the gypsy moth population decreasing.MALE STUDENT:How can we know that for sure?It seems like a big jump from more acorns to fewer gypsy moths.

FEMALE PROFESSOR:Well,we can know for sure because in this oak forest,the researchers decided to test the links between acorns and the two animal species.In some parts of the forest,they had volunteers drop a large number of extra acorns on the forest floor.

And in another section of the forest,they removed a number of white-footed mice.In the forest areas where extra acorns had been dropped,the gypsy moth population soon went into a significant decline.But in the section of the forest where the white-footed mice had been removed,the gypsy moth population exploded.

二、Relationships Among Species托福聽力中文翻譯：

旁白：在生物課上聽一節(jié)課的一部分。男學生：教授，既然我們要討論野生動物種群的變化，我想問一下我在網上讀到的一篇文章，關于一些動物物種的種群大小如何影響其他動物物種，以及其他環(huán)境因素如何發(fā)揮作用。女教授：對。特定生態(tài)系統中動物物種之間的關系可能變得相當復雜。因為除了捕食關系之外，還有其他影響種群規(guī)模的變量。男學生：這篇文章提到捕食者及其獵物的數量可能會迅速增加，然后突然下降。女生：哦。是啊我在生態(tài)學課上讀到過這方面的內容。它是循環(huán)發(fā)生的。我認為這就是所謂的繁榮與蕭條周期。正當女教授：好的。好吧，等一下。首先，我想回顧一些關鍵概念。比如說，有一個物種可以獲得充足的食物和理想的條件。在這種情況下，其人口將呈指數級增長，這意味著人口將以不斷加快的速度增長。男學生：哇！聽起來有點可怕。女教授：這通常不會發(fā)生。正如你所說，人口快速增長之后往往會突然下降。但當外來物種被移植到新環(huán)境中時，我們偶爾會看到它們呈指數級增長。嗯，因為它們面臨的競爭很少，而且有良好的生長條件。但對大多數物種來說，大多數時候，資源是有限的。只有這么多東西可以讓我明白我的觀點。每個生態(tài)系統都有我們所說的承載能力。承載力是一個物種的最大種群規(guī)模，可以由特定生態(tài)系統的資源維持。。。。當然，資源是食物、水，同樣重要的還有空間。雖然每個物種都有一個最大的種群增長率，但前提是該物種在其環(huán)境中的理想條件。總會有一些環(huán)境因素限制人口增長。這就是所謂的環(huán)境阻力。環(huán)境阻力很重要，因為它可以阻止人口失控增長。食物供應、捕食和疾病等因素會影響種群數量，并可能年復一年或季節(jié)性變化。男學生：好的。我想我明白了。女教授：好吧，讓我們看一個案例研究。這應該讓事情變得清楚。幾年前，我的一些同事在橡樹林中進行了一項實驗，涉及三種不同的物種：白足鼠、吉普賽蛾和橡樹。好啊現在讓我解釋一下這片森林的情況。橡樹產橡子，橡子是白足鼠的主要食物來源。白足鼠的另一個食物來源是吉普賽蛾。因此，吉卜賽蛾種群的大小由白足鼠控制，這是一件好事，因為吉卜賽蛾毛蟲被認為是害蟲。他們每隔十年左右就把橡樹的葉子剝掉一次。男學生：所以老鼠吃橡樹的橡子和吉普賽蛾。吉普賽蛾毛蟲吃橡樹的葉子。女教授：對?，F在，讓這組關系特別有趣的是，橡樹每隔幾年只產一次大量的橡子。男學生：所以在橡子較少的年份，白腳老鼠必須處理較少的食物供應。女教授：是的。但是在有大量橡子的年份，老鼠有更多的食物，這導致了什么？男學生：白腳老鼠的數量在增長。女教授：吉普賽蛾的數量在減少。男學生：我們怎么能確定呢？從更多的橡子到更少的吉普賽飛蛾，這似乎是一個巨大的飛躍。

女教授：嗯，我們可以肯定，因為在這片橡樹林中，研究人員決定測試橡子和這兩種動物之間的聯系。在森林的一些地方，他們讓志愿者將大量額外的橡子扔在森林地面上。

在森林的另一部分，他們移除了一些白腳老鼠。在多掉橡子的森林地區(qū)，吉普賽蛾的數量很快顯著下降。但在白足鼠被移除的森林區(qū)域，吉普賽蛾數量激增。

三、Relationships Among Species托福聽力問題：

Q1:1.What is the lecture mainly about?

A.Ways species in an ecosystem affect each other's population size

B.How the carrying capacity of an ecosystem is determined

C.A new theory regarding cycles in predator and prey population sizes

D.How researchers monitor the population size of animal species in the wild

Q2:2.Why does the professor mention nonnative species?

A.To show that some species cannot be transplanted easily to new environments

B.To give an example of rapid population growth that is not followed by decline

C.To emphasize that species with rapidly growing populations harm ecosystems

D.To introduce a study on the changing population size of certain species

Q3:3.What point does the professor make when she discusses the carrying capacity of an ecosystem?

A.The availability of food is more important for species than the availability of space.

B.The amount of environmental resistance in an ecosystem does not change over time.

C.Environmental resistance controls the population size of species in an ecosystem.

D.The population size of most species increases at a constant rate.

Q4:4.How did the researchers test the links between acorns,white-footed mice,and gypsy moths in a forest?

A.They supplied an additional food source for gypsy moths.

B.They introduced gypsy moths to areas where there had been none.

C.They cleared oak trees from some areas where both animal species lived.

D.They manipulated the numbers of mice and acorns in some areas.

Q5:5.What does the professor say can lead to a change in the gypsy moth population in a forest?[Click on 2 answers.]

A.An increase in the number of tree species in a forest

B.An increase in the number of acorns produced by oak trees

C.A decrease in the population of white-footed mice

D.A decrease in oak tree leaves caused by gypsy moth caterpillars

Q6:6.What can be inferred about the professor when she says this?

A.She does not know the answer to the student’s question.

B.She wants to correct a statement she made earlier.

C.She thinks the term the student used is incorrect.

D.She would like to redirect the discussion.

四、Relationships Among Species托福聽力答案：

A1:正確答案：A

A2:正確答案：B

A3:正確答案：C

A4:正確答案：D

A5:正確答案：BC

A6:正確答案：D

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