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2018专八阅读理解练习题《生物知识》
尽管现在离2018的专八考试还比较遥远，但是不少的考生已经在备考2018年的专八考试了。下面，小编就为考生送上一篇2018专八阅读理解练习题。
If you go down to the woods today, you may meet high-tech trees genetically modified to speed their growthor improve the quality of their wood. Genetically-engineered food crops have become increasingly common, albeit controversial. over the past ten years. But genetic engineering of trees has lagged behind.
Part of the reason is technical. Understandng. and then altering, the genes of a big pine tree are more complex than creating a better tomato. While tomatoes sprout happily, and rapidly, in the laboratory, growing a whole tree from a single, genetically altered cell in a test tube is a tricky process that takes years, not months. Moreover. little is known about tree genes. Some trees, such as pine trees. have a lot of DNA-roughly ten times as much as human. And, whereas the Human Genome Project is more than half-way throughits task of isolating and sequencing the estimated 100,00 genes in human cells. similar efforts to analyzetree genes are still just saplings (幼苗).
Given the large number of tree genes and the little that is known about them, tree engineers are starting with a search for genetic "markers". The first step is to isolate DNA from trees with desirable propertiessuch as insect resistance. The next step is to find stretches of DNA that show the presence of a particular gene. Then, when you mate two trees with different desirable properties, it is simple to check which offspring contain them all by looking for the genetic markers. Henry Amerson, at North Carolina State University, is using genetic markers to breed fungal resistance into southern pines. Billions of these are grown across America for pulp and paper, and outbreaks of disease are expensive. But not all individual trees are susceptible. Dr. Amerson’s group has found markers that distinguish fungus-resistant stock from disease-prone trees.Using traditional breeding techniques, they are introducing the resistance genes into pines on test sites in America.
Using generic markers speeds up old-fashioned breeding methods becauseyou no longer have to wait for the tree to grow up to see if it has the desiredtraits. But it is more a sophisticated form of selective breeding. Now. however.interest in genetic tinkering (基因修补) is also gaining ground. To this end, Dr.Amerson and his colleagues are taking part in the Pine Gene Discovery Project. an initiative to identify and sequence the 50,000-odd genes in the pine tree's genome. Knowing which gene does what should make it easier to know what to alter.
1. Compared with genetic engineering of food crops, genetic engineering of trees____________________.
A) began much later
B) has developed more slowly
C) is less useful
D) was less controversial
2. What does the author think about the genetic engineering of pine trees?
A) Time-consuming.
B) Worthwhile.
C) Significant.
D) Technically impossible.
3. What can we learn about the research on tree genes?
A) The research methods are the same as the analysis of human genes.
B) The findings are expected to be as fruitful as the analysis of human genes.
C) It will take as much time and effort as the analyst, of human genes.
D) The research has been mainly concentrated on the genes of young trees.
4. It is discovered by Henry Amerson’s team that_______________.
A) southern pines cannot resist fungus
B) all southern pines are not susceptible
C) the genetic marker in southern pines was the easiest to identify
D) fungus-resistant genes came originally from outside the U.S.A.
5. What is the primary objective of carrying out the Pine Gene Discovery Project?
A) To speed up old-Fashioned breeding methods.
B) To identify all the genes in the pine tree's genome.
C) To find out what desired traits the pine trees have.
D) To make it easier to know which gene needs altering.
答案：
1.相较于粮食作物的基因工程，树木的基因工程______________。
A)开始得较晚
B)发展得较慢
C)用处较小
D)争议性较低
[B]本文并没有提到树木基因改良技术从什么时候开始，所以有可能树木的基因改良技术和别的基因改良技术在开始的时间上相差不大，但在所取得的成果方面却有很大的差别，因此，本题关键在于理解首段末句中的lag behind指的是程度上的落后，而非时间上的落后，故B正确。
2.作者对于松树基因工程怎么看?
A)耗时。
B)十分值得。
C)很重要。
D)技术上不可能。
[B]第2段第3句中的that takes years表明研究树木的基因改造技术将花费很长时间，因此选项A为本题答案。原文没有就选项B和C两方面做出讨论，因此不能推断出这两个选项;虽然第2段首句提到technical一词，但文章表明树木基因改造技术是可行的。只是会花费较多的时问，因此选项D也不正确。
3.对于树木基因进行的研究，我们了解到什么?
A)研究方法与分析人类基因时相同。
B)人们预计研究成果会与人类基因分析一样硕果累累。
C)所花的时间和精力与人类基因分析一样多。
D)研究主要关注在小树的基因上面。
[A]第2段末句中的similar cfforts指的就是task of isolating and sequencing，即分析基因的常用方法。该句表明人类基因和树种基因的分析方法相同，但进展有差别，因此选项A为正确的推断。
4.Henry Amerson的研究小组发现，__________________。
A)南部黄松不能抵抗真菌
B)并不是所有的南部黄松都很容易染病
C)南部黄松的基因标记最容易识别
D)有真菌抵抗能力基因源自国外而非美国
[B]选项B是一个半否定的句式，因此本题关键在于理解选项B的Al1...are not...结构在意义上等同于第3段倒数第3句的not all... are...。第3段倒数第2句中的fungus-resistant stock指的是南方松树中能抗真菌的树种，并非别的与南方松树毫不相关的树种，因此A的说法不正确。
5.开展“松树基因发现项目”的主要目的是什么?
A)加快旧式的育种方法。
B)识别松树基因组中的所有基因。
C)找到松树所具有的优质特点。
D)让发现什么基因需要做改变的过程变得更加简单。
[B]末段倒数第2句中的an initiative...是the Pine Gene Discovery Project的同位语，表明开展该计划的目的，因此选项B为本题答案。其他选项都是在完成该计划后能够达成的工作，它们都要以松树基因的排列组合为基础，因此，这些选项都不是primary objective，而是在实现了primary objective之后继续进行的工作。
附：2018专八阅读技巧推荐
略读
略读(skimming)是常用的阅读方法之一，其主要特征是选择性地阅读。通常的阅读要求看到每一个词，每次注目看1-2个词。略读不需要看到每一个词，眼睛跳动的频率和幅度都有较大的提高，有时甚至从上一行跳到下一行。略读不可能使你对所读内容全部了解，但是你能大大地提高阅读速度，也能获得大量的信息。
略读的主要作用是了解文章的大意。经过略读之后，你对所读内容已经有了大致的了解，再仔细阅读，这时你的印象会更深刻，理解更透彻。
大部分读者不需要正规的训练和指导就可以进行略读。但是有意识地训练会大大地提高。你的略读速度和效率。进行略读训练的最简单的方法是强迫自己在规定的时间内读完某一篇文章，开始训练时，可以把略读速度定为平常阅读的5/4倍，以后逐步提高。略读的关键是增加眼跳的幅度，高度集中注意力，努力捕捉那些能引起注意或者你认为重要的内容。
扫读
扫读(scanning)是以最快的速度扫视所读材料，在找到所需信息时才仔细阅读该项内容。如查找某个人名、地名、时间、地点等，也即在寻找特定信息、寻找具体事实、寻找答题所需内容时都用这种方法。
研读
研读(study reading)就是仔细阅读，对文章有透彻深刻的理解。根据考题，运用上下文、逻辑关系、背景知识进行判断和推论。对难句的理解和翻译用得着这种方法。提高阅读速度的一个重要内容是扩大词汇量。其必要性表现在以下几个方面：
1. 词汇量决定了你的阅读理解能力，词汇量越大，你阅读得越广，视野就越开阔，你阅读理解的得分就越高。
2. 有限的词汇量必然会影响你阅读理解能力的提高。
生词的含义只有在上下文中才能完全展现出来，并易于被识记、理解、掌握。换句话说，是上下文给某个词以特定含义，而这个特定含义往往是字典无法提供的。有的人或许会说，我们从中学到大学英语词汇都是通过背生词表来记的。但是这样说的读者忽视了很重要的一点：所学课文后面的词汇表都是为课文服务的，而且，教师上课时对某些词或表达方式所举的实例，实质上是为它们设置上下文。不少教师鼓励学生背句子、段落、或整篇文章，都是出于同一目的，即要学生在上下文中理解并掌握词汇和短语。
3. 多读是扩大词汇量的最好的方法。不仅要读不同体裁的书和文章，而且要多接触不同题材，才能适应考试的需要。
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