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On June 26, 2000, two scientists, called Francis Collins and Craig Venter, told the world that they could read the whole “map” of the human body: DNA. DNA is something that everybody has, and it tells the body what to do. DNA is the reason that we look like our mother and father, because we get some of their DNA to make our own.
People have been trying to understand the human body for a long time. In 1860, Gregor Mendel discovered a special reason why we look the same as other people in our family. It is because of small things named “genes” in our body. In 1953, James Watson and Francis Crick made another discovery and found out that those small parts are real messages written in the DNA with a special language.
In 1961, Marshall Nirenberg and Johann Matthaci found a message in DNA showing how DNA tells the cell(细胞)to build its parts. Scientists have now found all the words in the DNA map, but we still do not understand what they all do. By understanding what just one “word” means, we can help save more people from several illnesses.
Most people hope that this will help make better medicine and help sick people. Other people worry that when people begin to know more words and find out lots of other information, we might use it in a wrong way, just to make people more attractive, or stop sick people from getting jobs. Man would have to meet a lot of trouble if DNA technic wasn’t limited(限制)in use.
1.When did we first know why we look like other people m our family?
A.In 1860 B.In 1953 C.In 1961 D.In 2000
2.What does the underlined word “ genes” mean?
A. The “map” of DNA. B. A special language.
C. Small parts of DNA. D. DNA
3.What did the two scientists first discover in 1961 ?
A. The “map” of DNA. B. A new illness.
C. The language of DNA. D. A message of DNA.
4.What can we do if we understand some “ words” of the language inside the body
A.Make people get new jobs.
B.Make medicine for illnesses.
C.Make maps of human.
D.Make people less attractive.
5.What do people think about this work’?
A.It can cause good or bad results.
B.It can cause only good results.
C.It can cause good results but won’t work.
D.It can cause only bad results.
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On June 26, 2000, two scientists, called Francis Collins and Craig Venter, told the world that they could read the whole “map” of the human body: DNA. DNA is something that everybody has, and it tells the body what to do. DNA is the reason that we look like our mother and father, because we get some of their DNA to make our own.
People have been trying to understand the human body for a long time. In 1860, Gregor Mendel discovered a special reason why we look the same as other people in our family. It is because of small things named “genes” in our body. In 1953, James Watson and Francis Crick made another discovery and found out that those small parts are real messages written in the DNA with a special language.
In 1961, Marshall Nirenberg and Johann Matthaci found a message in DNA showing how DNA tells the cell(细胞)to build its parts. Scientists have now found all the words in the DNA map, but we still do not understand what they all do. By understanding what just one “word” means, we can help save more people from several illnesses.
Most people hope that this will help make better medicine and help sick people. Other people worry that when people begin to know more words and find out lots of other information, we might use it in a wrong way, just to make people more attractive, or stop sick people from getting jobs. Man would have to meet a lot of trouble if DNA technic wasn’t limited(限制)in use.
【小题1】When did we first know why we look like other people m our family?
| A.In 1860 | B.In 1953 | C.In 1961 | D.In 2000 |
A. The “map” of DNA. B. A special language.
C. Small parts of DNA. D. DNA
【小题3】What did the two scientists first discover in 1961 ?
A. The “map” of DNA. B. A new illness.
C. The language of DNA. D. A message of DNA.
【小题4】What can we do if we understand some “ words” of the language inside the body
| A.Make people get new jobs. |
| B.Make medicine for illnesses. |
| C.Make maps of human. |
| D.Make people less attractive. |
| A.It can cause good or bad results. |
| B.It can cause only good results. |
| C.It can cause good results but won’t work. |
| D.It can cause only bad results. |
DNA is the whole “map” of the human body. It is something that all humans have, and it tells the body what to do. DNA is the reason that we look like our parents, because we get some of their DNA to make our own.
People have been trying to understand the human body for a long time, In1860, Mr Mendel discovered why we look the same as other people in our family. It is because of small things called “genes”(基因) in our body. In 1953, two scientists, Watson and Crick, found out that those small parts are really messages . They’re written in the DNA with a special language.
In1961, another two scientists found the first “word” that they could understand in that language. It shows how DNA tells the cell﹙细胞﹚to build its parts. So far, scientists have found all the words in the DNA map, but we still do not understand what they all do. By understanding what just one “word ”means, we can help to save people from several illness. So the more we understand, the more doctors will be able to do.
Most people hope that this will help to make better medicine and help sick people. Other people worry that when we learn more “words” and find out more information, we will use it in the wrong way, just to make people more attractive (有吸引力的),or stop sick people getting jobs.
1.When did Mr Mendel discover why we look the same as other people in our family?
A. In 2000. B. In 1961 C. In 1953 D In 1860
2.What did the two scientists find in 1961? They found_____.
A.all the words in the DNA map
B.Small things called “genes” in our body
C.The first “word” they could understand in that language
D.those small parts are written in the DNA with a special language
3.How can we help sick people if we understand more “words” in the DNA map?
A.Make better medicine. B.Make them get jobs.
C.Make maps for them. D.Make them attractive
4.Which one is not true according to the article?
A.We look like our parents because of “genes” in our body
B.We have understand what all the words in the DNA map do
C.DNA is the whole “map” of the human body.
D.DNA tells the cell to build its parts.
5.What do people think about this research about DNA?
A.It can be only bad B.It can be only good
C.It can be good but won’t work D.It can be good and bad
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First of all, it's important to find that not all plant cells have a cell wall. Besides, there are many differences of a cell wall based on the kinds of plant. The following is meant to be what a plant cell wall is like.
The cell wall of a plant is on the outside of the cell membrane (膜). It is usually hard and cannot be bent easily, but the degree of flexibility (韧性) of the cell wall is different. It is based on the special use that the cell has in keeping the plant alive. Cells that make up the trunk of a tree are clearly less flexible than cells on a leaf.
Cell walls act in many ways. They serve to protect the plant. They provide support, as well as help in the movement of chemicals and wastes into and out of the cell. More importantly, they control the water that goes in and out. Plants must have good water controlling systems (系统), allowing them to keep water during dry seasons, and get rid of unnecessary water. Plants can't walk around to find water, so being able to control water is very important.
So there you have it , what a plant cell wall is. Of course, there are many other things that are not talked about here. Knowing more about plant cell wails requires further study and research.
小题1:From the first two paragraphs we can find that _____.
| A.all plants have a ceil wall |
| B.plant cells and animal cells are the same |
| C.different kinds of plant have different cell walls |
| D.there are no differences between the cells of a tree and a dog |
| A.变形的 | B.防水的 | C.太阳灼伤的 | D.表皮破损的 |
| A.as flexible as | B.not so flexible as |
| C.more important than | D.less important than |
| A.To protect the plant. | B.To provide support. |
| C.To move chemicals and wastes. | D.To control the water. |