题干

关于下列微生物所需要的氮源物质的说法不正确的是:①分子态氮②氨③铵盐④硝酸盐⑤尿素⑥牛肉膏⑦蛋白胨(   )

A:③④等是微生物最常用的氮源

B:固氮微生物把②转变为①

C:⑤⑥⑦既是氮源又是碳源

D:氮源用于合成蛋白质、核酸及其他含氮物质

上一题 下一题 0.0难度 选择题 更新时间:2016-12-13 05:21:28

答案(点此获取答案解析)

B

同类题1

Teens Enjoy Reading
     According to a survey on reading conducted by the U.S. National Education Association (NEA), young Americans say reading is important—more important than computers and science. Over 50% of the twelve to eighteen years old children interviewed said they enjoy reading a lot. Seventy-nine percent find it stimulating and interesting, and 87% think it is relaxing. Most of those surveyed (68%) disagree with the opinion that reading is boring, or old-fashioned.
Teens Read Variety of Material
    Over half the teenagers interviewed said they read more than ten books a year. The results also showed that middle school students read more books than high school students. Most teens (66%) like to read fiction, such as novels and stories. Only 26% were interested in non-fiction, such as biographies and history books. Sixty-four percent of students liked reading ‘stories about people of my own age’ as their favorite topic. Mysteries and detective stories came second on the list at 53%. Just under 50% said they were interested in reading about their own culture and heritage.
Other Interests
    Of the teenagers who took part in the survey, 49% said that libraries are where they get most of their books. However, many complained that their school libraries do not have enough up-to-date, interesting books and magazines. Even though many teenagers in the U.S. enjoy reading, they still have other interests. When asked which activity would be the most difficult to give up for a week, 48% said listening to music. TV would be difficult to give up for 25% of those surveyed.
  ____
    Another survey which is published by www. SmartGirl.com studied the differences between teenage boys' and girls' reading habits. According to the report, more girls than boys read for fun. Many more girls (77%) than boys (6%) read fashion and beauty magazines. More boys (47%)  than girls (7%) read magazines about video games, but an equal number of each like to read adventure stories and newspapers. Girls also read more material about celebrities and social issues such as crime, drugs, or poverty. Boys, on the other hand, read more about sports.