日日人人_亚洲美女在线视频_av手机在线播放_国产大片aaa_欧美中文日韩_午夜理伦三级


D
With only about 1, 000 pandas left in the world, China is desperately trying to clone(克隆) the animal and save the endangered species(物種). That’s a move similar to what a Texas A & M University researchers have been undertaking for the past five years in a project called “Noah’s Ark”.
Noah’s Ark is aimed at collecting eggs, embryos(胚胎), semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A & M’s College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.
It is estimated that as many as 2, 000 species of mammals, birds reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.
This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.
The entire procedure could take from three to five years to complete.
“The nuclear transfer(核子移植) of one species to another is not easy, and the lack of available(capable of being used) panda eggs could be a major problem,” Kraemer believes. “They will probably have to do several hundred transfers to result in one pregnancy (having a baby). It takes a long time and it’s difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort,” adds Kraemer, who is one of the leaders of the Project at Texas A& M, the first-ever attempt at cloning a dog.
“They are trying to do something that’s never been done, and this is very similar to our work in Noah’s Ark. We’re both trying to save animals that face extinction. I certainly appreciate their effort and there’s a lot we can learn from what they are attempting to do. It’s a research that is very much needed.”
69. According to Professor Kraemer, the major problem in cloning pandas would be the lack of _______.
A. available panda eggs                     B. host animals
C. qualified researchers                     D. enough money
70. The best title for the passage may be _______.
A. China’s Success in Pandas Cloning   
B. The First Cloned Panda in the World
C. Exploring the Possibility to Clone Pandas
D. China —the Native Place of Pandas Forever
71. From the passage we know that _______.
A. Kraemer and his team have succeeded in cloning a dog
B. scientists try to implant a panda’s egg into a rabbit
C. Kraemer will work with Chinese scientists in clone researches
D. about two thousand of species will probably die out in a century

練習(xí)冊(cè)系列答案
相關(guān)習(xí)題

同步練習(xí)冊(cè)答案
主站蜘蛛池模板: 国产精品久久久久久久久久东京 | 女同久久另类99精品国产 | 色欧美综合 | 国产自产精品视频 | 国产传媒在线 | 婷婷精品在线 | 在线观看免费av的网址 | 日韩在线免费 | 亚洲在线一区二区 | 黄网址在线观看 | 99亚洲国产 | 午夜视频在线免费观看 | 国产乱人伦av在线a 日韩电影中文字幕 | 久久精品亚洲a | av网战 | 亚洲一区中文字幕在线观看 | 国产精品久久久久久久久久久久久 | 草草视频在线观看 | 久久国产精品99久久久久久牛牛 | 国产美女高潮一区二区三区 | 日韩精品在线观看视频 | 夜夜av| 亚洲不卡视频 | 81精品国产乱码久久久久久 | 国产精品精品视频一区二区三区 | 日本精品免费 | 亚洲国产精品一区二区第一页 | 国产精品久久久久久久久免费丝袜 | 亚洲国产伊人 | 最新黄网在线观看 | 仙踪林久久久久久久999 | 久草精品在线 | 成人一区二区三区 | 日本激情视频在线播放 | 日本久久久亚洲精品 | 亚洲成人精品网 | 成人在线观看一区 | 毛片毛片毛片毛片毛片毛片毛片毛片 | 亚洲色图偷拍自拍 | 毛片91| 极品女神高潮呻吟av久久 |