问题 单项选择题 A1型题

下列关于酮体的描述错误的是()

A.酮体包括乙酰乙酸、β-羟丁酸和丙酮

B.合成原料是丙酮酸氧化生成的乙酰CoA

C.只能在肝的线粒体内生成

D.酮体只能在肝外组织氧化

E.酮体是肝输出能量的一种形式

答案

参考答案:B

解析:酮体是脂肪酸在肝线粒体分解氧化时特有的中间代谢产物,是输出能量的一种形式,酮体包括乙酰乙酸、β-羟丁酸和丙酮,合成原料是脂肪酸在线粒体中经β-氧化生成的乙酰CoA,酮体只能在肝外组织氧化,因为肝缺乏利用酮体的酶系。故本题选B。

单项选择题

With only about 1,000 pandas left in the world, China is desperately trying to clone the animal and save the endangered species. That’s a move similar to what a Texas A&M University researcher has been undertaking for the past five years in a project called "Noah’s Ark".

Dr. Duane Kraemer, a professor in Texas A&M’s College of Veterinary Medicine and a pioneer in embryo transfer work and related procedures, says he salutes the Chinese effort and "I wish them all the best success possible. It’s a worthwhile project, certainly not an easy one, and it’s very much like what we’re attempting here at Texas A&M—to save animals from extinction. "

Noah’s Ark is aimed at collecting eggs, embryos, semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Kraemer 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 and reptiles will become extinct over the next 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 of one species to another is not easy, and the lack of available panda eggs could be a major problem," Kraemer believes. "They will probably have to do several hundred transfers to result in one pregnancy. 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 Missyplicity 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 applaud 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.

How long will the Chinese panda-cloning project take according to the passage()

A. 1 year

B. 3 to 5 years

C. 2 years

D. 25 years

多项选择题