英語六級生物知識閱讀練習題

If you go down to the woods today, you may meethigh-tech trees genetically modified to speed theirgrowthor improve the quality of their wood. Genetically-engineered food crops have becomeincreasingly common, albeit controversial. overthe past ten years. But genetic engineering of treeshas lagged behind.

Part of the reason is technical. Understanding. and then altering, the genes of a big pine treeare 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 isa 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 andsequencing the estimated 100,00 genes in human cells. similar efforts to analyzetree genesare still just saplings (幼苗).

Given the large number of tree genes and the little that is known about them, tree engineersare starting with a search for genetic "markers". The first step is to isolate DNA from treeswith desirable propertiessuch as insect resistance. The next step is to find stretches of DNAthat show the presence of a particular gene. Then, when you mate two trees with differentdesirable properties, it is simple to check which offspring contain them all by looking for thegenetic markers. Henry Amerson, at North Carolina State University, is using genetic markersto breed fungal resistance into southern pines. Billions of these are grown across America forpulp and paper, and outbreaks of disease are expensive. But not all individual trees aresusceptible. Dr. Amerson’s group has found markers that distinguish fungus-resistantstock from disease-prone g traditional breeding techniques, they are introducingthe resistance genes into pines on test sites in America.

Using generic markers speeds up old-fashioned breeding methods becauseyou no longer haveto wait for the tree to grow up to see if it has the desiredtraits. But it is more a sophisticatedform of selective breeding. Now. rest in genetic tinkering (基因修補) is alsogaining ground. To this end, son and his colleagues are taking part in the Pine GeneDiscovery Project. an initiative to identify and sequence the 50,000-odd genes in the pinetree's genome. Knowing which gene does what should make it easier to know what to alter.

1. Compared with genetic engineering of foodcrops, genetic engineering oftrees____________________.

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.

1.相較於糧食作物的基因工程，樹木的基因工程______________。

A)開始得較晚

B)發展得較慢

C)用處較小

D)爭議性較低

[B]本文並沒有提到樹木基因改良技術從什麼時候開始，所以有可能樹木的基因改良技術和別的基因改良技術在開始的時間上相差不大，但在所取得的成果方面卻有很大的差別，因此，本題關鍵在於理解首段末句中的lagbehind指的是程度上的落後，而非時間上的落後，故B正確。

2.作者對於松樹基因工程怎麼看?

A)耗時。

B)十分值得。

C)很重要。

D)技術上不可能。

[B]第2段第3句中的that takes years表明研究樹木的基因改造技術將花費很長時間，因此選項A為本題答案。原文沒有就選項B和C兩方面做出討論，因此不能推斷出這兩個選項;雖然第2段首句提到technical一詞，但文章表明樹木基因改造技術是可行的。只是會花費較多的時問，因此選項D也不正確。

3.對於樹木基因進行的研究，我們瞭解到什麼?

A)研究方法與分析人類基因時相同。

B)人們預計研究成果會與人類基因分析一樣碩果累累。

C)所花的時間和精力與人類基因分析一樣多。

D)研究主要關注在小樹的基因上面。

[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。該句表明人類基因和樹種基因的分析方法相同，但進展有差別，因此選項A為正確的.推斷。

y Amerson的研究小組發現，__________________。

A)南部黃鬆不能抵抗真菌

B)並不是所有的南部黃鬆都很容易染病

C)南部黃鬆的基因標記最容易識別

D)有真菌抵抗能力基因源自國外而非美國

[B]選項B是一個半否定的句式，因此本題關鍵在於理解選項B的 not...結構在意義上等同於第3段倒數第3句的not all... are...。第3段倒數第2句中的fungus-resistant stock指的是南方松樹中能抗真菌的樹種，並非別的與南方松樹毫不相關的樹種，因此A的說法不正確。

5.開展“松樹基因發現專案”的主要目的是什麼?

A)加快舊式的育種方法。

B)識別松樹基因組中的所有基因。

C)找到松樹所具有的優質特點。

D)讓發現什麼基因需要做改變的過程變得更加簡單。

[B]末段倒數第2句中的an initiative...是the Pine Gene Discovery Project的同位語，表明開展該計劃的目的，因此選項B為本題答案。其他選項都是在完成該計劃後能夠達成的工作，它們都要以松樹基因的排列組合為基礎，因此，這些選項都不是primary objective，而是在實現了primary objective之後繼續進行的工作。