题目内容
Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes.Scientists have found the gene that determines skin color.
The gene comes in two versions, one of which is found in 99 per cent of Europeans.The other is found in 93 t0 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.
Scientists have changed the color of a dark - striped zebrafish(斑马鱼) to uniform gold by inserting a version of the pigment(色素) gene into a young fish.As with humans, zebrafish skin color is deter-mined by pigment cells,which contain melanin(黑色素).The number, size and darkness of melanin perpigment cell determine skin color.
It appears that, like the golden zebrafish, light - skinned Europeans also have a mutation (变异) in the gene for melanin production.This results in less pigrnented skin.
However, Keith Cheng, leader of the research team, points out that the mutation is different in hu-man ancl zebrafish genes.
Humans acquired dark skin in Africa about l.5 million years ago to protect bodies from ultra - violetrays of the sun. which can cause skin cancer.
But when modem humans leave Africa to live in northem latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.
Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.
The new discovery could lead to medical treatments for skin cancer.lt also could lead to research in-to ways to change skin color without damaging it like chemical treatment did on Michael Jackson.
【小题1】Scientists have done an experiment on a dark -striped zebrafish in order to
A.fincl the different genes o humans' |
B.prove the humans' skin color is determined by the pigment gene |
C.find out the reason why the Africans' skin color is dark |
D.fincl out the ways of changing people's skin color |
A.nowadays people who want to change their skin color have to suffer 8 lot from the damage caused by the chemical treatment |
B.Europeans and Africans have the same gene |
C.the new discovery could help to find medical treatments for skin cancer |
D.there are two kinds of genes |
A.scientists have found out that people's skin color is determined by the gene |
B.the new discovery could lead to research into ways to change skin color safely |
C.pop king Michael Jackson often changed his skin color as he liked |
D.people can not change their skin color without any pain |
A.they are bom light - skinned people |
B.light - skinned Europeans have mutation in the gene for melanin production |
C.they have fewer activities outside |
D.they pay much attention to protecting their skin |
A.neutral | B.negative | C.indifferent | D.positive |
【小题1】B
【小题2】A
【小题3】A
【小题4】B
【小题5】D
解析
“If I had one million yuan, I would buy you a palace! Do I have one million yuan? No, I don’t! so I only can spend ten fen(分) on this short message, sending you my best wishes! ”
Today, SMS—Short Message Service is popular, and China Mobile says that every second, there are 410 messages being sent.
Look around you! People are watching their mobiles, smiling or laughing. Thumbs are pressing buttons, bring happiness to their friends. The humor of the words shows how beautiful language is! Through SMS, we know the weather report, share jokes and news, express love and friendship.
“Thumb Culture” is becoming more and more popular. It is reported that 67% of young people like to “Short” to greet each other. Internet SMS will provide more convenience to people. I am grateful for the progress because SMS saves me much money. Just on the tip of thumb, so much joy can be found!
【小题1】The first paragraph is a(n) __________.
A.e-mail. | B.short message. | C.piece of news. | D.story. |
A.Buy a palace. | B.Provide food. |
C.Learn foreign language. | D.Send messages. |
A.save much money. | B.know the weather report. |
C.enjoy the happiness of SMS. | D.have one million yuan. |
A.SMS helps people a lot. | B.people can find joy on the Internet. |
C.greeting can cost much money. | D.thumb has become a kind of culture. |