Relationships Among Species托福听力原文翻译及问题答案

Relationships Among Species托福听力原文翻译及问题答案

一、Relationships Among Species托福听力原文：

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托福听力中文翻译：

旁白：在生物课上听一节课的一部分。男学生：教授，既然我们要讨论野生动物种群的变化，我想问一下我在网上读到的一篇文章，关于一些动物物种的种群大小如何影响其他动物物种，以及其他环境因素如何发挥作用。女教授：对。特定生态系统中动物物种之间的关系可能变得相当复杂。因为除了捕食关系之外，还有其他影响种群规模的变量。男学生：这篇文章提到捕食者及其猎物的数量可能会迅速增加，然后突然下降。女生：哦。是啊我在生态学课上读到过这方面的内容。它是循环发生的。我认为这就是所谓的繁荣与萧条周期。正当女教授：好的。好吧，等一下。首先，我想回顾一些关键概念。比如说，有一个物种可以获得充足的食物和理想的条件。在这种情况下，其人口将呈指数级增长，这意味着人口将以不断加快的速度增长。男学生：哇！听起来有点可怕。女教授：这通常不会发生。正如你所说，人口快速增长之后往往会突然下降。但当外来物种被移植到新环境中时，我们偶尔会看到它们呈指数级增长。嗯，因为它们面临的竞争很少，而且有良好的生长条件。但对大多数物种来说，大多数时候，资源是有限的。只有这么多东西可以让我明白我的观点。每个生态系统都有我们所说的承载能力。承载力是一个物种的最大种群规模，可以由特定生态系统的资源维持。。。。当然，资源是食物、水，同样重要的还有空间。虽然每个物种都有一个最大的种群增长率，但前提是该物种在其环境中的理想条件。总会有一些环境因素限制人口增长。这就是所谓的环境阻力。环境阻力很重要，因为它可以阻止人口失控增长。食物供应、捕食和疾病等因素会影响种群数量，并可能年复一年或季节性变化。男学生：好的。我想我明白了。女教授：好吧，让我们看一个案例研究。这应该让事情变得清楚。几年前，我的一些同事在橡树林中进行了一项实验，涉及三种不同的物种：白足鼠、吉普赛蛾和橡树。好啊现在让我解释一下这片森林的情况。橡树产橡子，橡子是白足鼠的主要食物来源。白足鼠的另一个食物来源是吉普赛蛾。因此，吉卜赛蛾种群的大小由白足鼠控制，这是一件好事，因为吉卜赛蛾毛虫被认为是害虫。他们每隔十年左右就把橡树的叶子剥掉一次。男学生：所以老鼠吃橡树的橡子和吉普赛蛾。吉普赛蛾毛虫吃橡树的叶子。女教授：对。现在，让这组关系特别有趣的是，橡树每隔几年只产一次大量的橡子。男学生：所以在橡子较少的年份，白脚老鼠必须处理较少的食物供应。女教授：是的。但是在有大量橡子的年份，老鼠有更多的食物，这导致了什么？男学生：白脚老鼠的数量在增长。女教授：吉普赛蛾的数量在减少。男学生：我们怎么能确定呢？从更多的橡子到更少的吉普赛飞蛾，这似乎是一个巨大的飞跃。

女教授：嗯，我们可以肯定，因为在这片橡树林中，研究人员决定测试橡子和这两种动物之间的联系。在森林的一些地方，他们让志愿者将大量额外的橡子扔在森林地面上。

在森林的另一部分，他们移除了一些白脚老鼠。在多掉橡子的森林地区，吉普赛蛾的数量很快显著下降。但在白足鼠被移除的森林区域，吉普赛蛾数量激增。

三、Relationships Among Species托福听力问题：

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托福听力答案：

A1:正确答案：A

A2:正确答案：B

A3:正确答案：C

A4:正确答案：D

A5:正确答案：BC

A6:正确答案：D