Question

    Humans have always been curious about what Earth was like thousands of years ago. To learn more about the plants and animals that lived during that time, scientists examine their fossils or other remains. In recent years, genetics, and in particular the the study of DNA, has become an important tool for these scientists. Some people even dream of bringing ancient creatures such as dinosaurs back to life. Although no animals have been brought back yet, scientists have managed to grow a number of ancient plants from seeds. By far theoldest of these plants is a 32,000-year-old plant that has been grown again by Russian scientists.

The plant is a flower called Silenestenophylla, which used to grow in Siberia in eastern Russia. The scientists discovered seeds and fruits of the plant buried deep below the ground. They believe the seeds and fruits were put there by an ancient animal which stored them to eat during the winter. The seeds that scientists found failed to grow because they were damaged. However, the scientists were able to take genetic material from the fruit to grow a new plant. Then, this plant produced new seeds which the scientists were able to use to grow more plants.

A modern relative of the original flower still grows in Siberia, but when the ancient flower was grown, it had some important differences from the modern flower. The petals on the ancient flower were much longer and also spaced further apart. Studying the ancient flower will allow the scientists to learn more about how plants have evolved.

Before this, the oldest seed to have been grown was from a 2,000-year-year-old tree in Israel. The Russian scientists believe the reason why the Siberian seeds were preserved for so long is that they were buried in permanently frozen earth, which protected the genetic information in the seeds. The scientists believe that the permanently frozen soil in Siberia contains many other ancient seeds, so they may be able to bring back even older plants. This will help them better understand the history of plants and how they have changed over time.

1.Recently, scientist have ________.

A.been able to bring a number of ancient animals back to life

B.begun using genetics to learn more about ancient plants and animals

C.started to create a dinosaur that could live on Earth today

D.tried to create new types of fossils to study how animals used to live

2.How were Russian scientists able to grow Silenestenophylla?

A.They used genetic material from an ancient fruit they discovered.

B.They used ancient seeds that they had found deep below the ground.

C.They planted the seeds deep in the ground to protect them during the cold winter.

D.They planted fruit in a new kind of container that they had specially designed.

3.What is one thing the Russian scientists learned by comparing the ancient plant with its modern relative?

A.The plant used to produce fewer flowers than it produces now.

B.The plant has evolved to have shorter petals on its flowers.

C.The ancient plant was a different color from its modern relative.

D.The modern plant is found across a wider area of Russia than the ancient one.

4.The Russian scientists believe that ________.

A.it is unlikely that they can grow plants from seeds that are over 2,000 years old

B.ancient seeds that were kept in Israel will be easier to grow than Russian seeds

C.they will be able to grow plants in areas where the earth is permanently frozen

D.the frozen soil in Siberia is able to keep the DNA of plants safe for a long time

5.Which of the following statements is true?

A.Russian scientists would like to use frozen earth to protect seeds.

B.Human DNA can be used to help scientists learn more about the genetic history of plants.

C.The fruit and seeds of Silenestenophylla may have been buried by an ancient animal.

D.The first plant that had flowers grew in Siberia over 32,000 years ago.

Answer

1.B

2.A

3.B

4.D

5.C

【解析】

这是一篇说明文。主要说明了科学家们已经设法从种子中培育出许多古代植物。俄罗斯科学家重新种植了这种植物。这种植物是一种被称为Silenestenophylla的花，曾生长在俄罗斯东部的西伯利亚。文章说明了这种植物与现代花的区别等情况。

1.细节理解题。根据第一段中To learn more about the plants and animals that lived during that time, scientists examine their fossils or other remains. In recent years, genetics, and in particular the study of DNA, has become an important tool for these scientists.可知为了更多地了解生活在那个时期的动植物，科学家们检查了它们的化石或其他遗骸。近年来，遗传学，特别是DNA的研究，已经成为这些科学家的重要工具。由此可知，最近，科学家们开始利用遗传学来更多地了解古代植物和动物。故选B。

2.细节理解题。根据第二段中However, the scientists were able to take genetic material from the fruit to grow a new plant.可知然而，科学家们能够从这种水果中提取遗传物质来培育一株新的植物。由此可知，俄罗斯科学家使用了他们发现的一种古代水果的遗传物质从而培育出了银叶蕨。故选A。

3.推理判断题。根据第三段中The petals on the ancient flower were much longer and also spaced further apart.可知古代花朵上的花瓣更长，间隔也更远。由此判断出，通过比较古代植物和现代植物，俄罗斯科学家发现这种植物在进化过程中花的花瓣变短了。故选B。

4.细节理解题。根据最后一段中The Russian scientists believe the reason why the Siberian seeds were preserved for so long is that they were buried in permanently frozen earth, which protected the genetic information in the seeds.可知俄罗斯科学家认为，西伯利亚种子保存如此之久的原因是它们被埋在永久冻土中，从而保护了种子中的遗传信息。由此可知，俄罗斯科学家认为，西伯利亚的冻土能够在很长一段时间内保持植物的DNA。故选D。

5.细节理解题。根据第二段中They believe the seeds and fruits were put there by an ancient animal which stored them to eat during the winter.可知俄罗斯科学家相信这些古代种子是由一种古老的动物放在那里的，这种动物在冬天储存它们以供食用。由此可知，银叶蕨的果实和种子可能是被一种古代动物埋起来的。故选C。