Official 39 Set 2

纠错
  • Q1
  • Q2
  • Q3
  • Q4
  • Q5
  • Q6
置顶

Mineral Evolution

纠错
  • Q1
  • Q2
  • Q3
  • Q4
  • Q5
  • Q6
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

显示答案 正确答案: D

我的笔记 编辑笔记

/
  • 原文
  • 译文
  • 查看听力原文

    关闭显示原文

    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 over 4,300 kinds 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.

    [word unstressed] 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 the environment 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 certain minerals 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.

  • 旁白:请听一段地质学讲座的节选片段。

    教授:自从地球在45亿年前形成开始,地球上的矿物种类的数量就发生了急剧增长,从只有仅仅几种相对简单的矿物质增长,到4300多种我们现在可以识别的矿物,其中的很多矿物很复杂。一个地质学的基本问题是,这些新的矿物质是怎么形成的。近期的研究转向了生物学,试图解释这些新生矿物的产生过程。

    生物学的大部分理论是通过进化的视角来研究的。进化的理论意思是,随着环境的改变,当然环境不可避免地一直在改变,一些有机物会产生让它们成功适应环境的特征,这些特征帮助这些有机物生长存活下来,再产生后代。随着时间的推移,当环境变得更加复杂的时候,这一些早期的生物的适应性和变种会成为进一步组合和变异的基础,从而产生更加多样和复杂的生命。所以从十亿年前数量少的、简单的和相对来说更加相似的生命形式,地球上的生物现在变成了一群有巨大多样性和复杂性的群体。

    一些地质学家现在想把这个理论应用到解释矿物质多样性上。矿物质所处的环境不是一成不变的。譬如温度、压强或者化学环境是一直在变化的,这一些变化,经常是循环往复发生, 随着时间增强或者减弱。随着环境的改变,它们的原子重新组合,成为新的化合物,这就是一个称为矿物质进化的过程的一部分。

    矿物质肯定不是活物,所以矿物质进化的概念和生物进化的概念是不同的。但是还是有很多过程是平行的。活体生物不仅仅要适应环境,还去改变环境,改变环境以后,这个环境可能会变得适宜其他有机体生长。类似地,每一种新的矿物质同样会丰富其化学环境,而这个化学环境是很多其他更复杂的矿物质未来会产生的发源地。

    除了这些相似点,矿物质进化的吸引人的一点是矿物质显然是和有机物一起进化的。嗯,我的意思具体是什么呢?也许是十亿年以前,在地球形成之后,我们第一次发现了生命存在的证据。当然了早期的生命体是原始的,仅仅是小小的,单细胞微生物,但是随着时间过去,它们起到了深远的作用。大量的这种微生物开始通过光合作用生产养料,光合作用释放了大量的氧气。氧气导致和当时存在的矿物质反应,形成了例如铁锈一样的东西,这些物质再和大范围的不同金属反应,最终产生多种矿物质。微生物依赖矿物质而生。但是它们并不是仅仅把矿物质作为营养物质而吸收,他们还分泌一些别的矿物质作为排泄物,包括我们称为生物矿物质的东西,这种物质是通过有机体的帮助下产生的。我们可以通过叠层石得到地质学上关于生物矿物质产生的证据。

    叠层石看起来像是一层层的沉积岩。但它们其实是化石,是微生物的一层层的残渣。微生物层是单细胞生物的巨大聚居地, 这些生物曾经是地球上最占优势的物种。针对叠层石的研究发现这些古代微生物层会与环境中的矿物质发生相互作用,产生新的化合物残渣,这种生物矿物质就是,例如碳酸盐、磷酸盐和二氧化硅这样的物质。实际上,我们已经可以在实验室里培养微生物层,随着时间的过去,它们也开始产生我们在叠层石里发现的相同的矿物质。嗯,你们不需要现在就知道这个过程的细节,我们现在也还在研究呢。

    但是你应该会对矿物进化这个概念怎么用在寻找其他星球的生命证据上面感兴趣。我们的想法是,如果一些矿物质在地球上产生了,是作为生物活动过程的结果产生的,并且如果我们在其他星球上也发现了这些矿物质,这就可以说明生命曾经在那里存在过!但是仅仅因为我们在火星上或者金星上找到了某种特定的矿物质,我们真的不应该假定,发生在地球上的过程也会在那里发生,也不应该假定在它们上面产生矿物质的过程和地球上的一样。

  • 官方解析
  • 网友贡献解析
  • 本题对应音频:
    0 感谢 不懂
    音频1
    解析

    题型分类:目的题

    题干分析:根据purpose定位

    音频定位:

    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.

    选项分析:

    讲座开头直接讲明主题新的矿物质是怎么形成的最近的研究开始从生物学角度来解释然后开始解释这个研究

    标签

题目讨论

如果对题目有疑问,欢迎来提出你的问题,热心的小伙伴会帮你解答。

如何吃透这篇文章?

Mineral Evolution

0人精听过

预计练习时间:16min32s

马上精听本文

最新提问