题干

下列有关“DNA粗提取与鉴定”实验的叙述,正确的是(  )

A:随NaCl溶液浓度增大,DNA的溶解度逐渐增大

B:新鲜的猪血细胞是用于DNA粗提取的理想材料

C:在酒精溶液中,某些蛋白质的溶解度大于DNA的溶解度

D:在50~60℃水浴中,DNA遇二苯胺试剂后即呈蓝色

上一题 下一题 0.0难度 选择题 更新时间:2013-06-27 04:19:51

答案(点此获取答案解析)

C

同类题3

阅读下面短文,根据其内容,从方框中选择适当的单词填在标有题号的空白处,使语意通顺、完整.(每空一词,切不可重复使用)

moving    direction    fall      hands      where    protect     yourself

against    as        up     possible     easily     them  thing   ground

 What should you do if you are in a crowd(人群)? The first and most important ____   is to make yourself clear where you are and where the exits are. No matter ____  you are, make sure you always know how to get out and to be safe.

 Make yourself know the type of  ____  you are standing on. Wet or uneven(不平坦的)ground can cause you to ____  down in a crowd of moving people.

 If you find ____   in the middle of a moving crowd, you must be careful. Do not walk ____  the moving direction and do not stop or sit down, because you could get trampled (踩踏)  ____ Instead, move in the same ____  of the crowd. Keep your____  up by your chest(胸部)to protect your chest. If you fall down, get up quickly, If you can't get  ____  , ask someone to pull you back up. If you have kids, lift  ____  up.

 If you fall and cannot get up, keep on  ____   in the same direction of the crowd. If that is not  ____   , then cover your head with your arms.

 Try to get away from hard things in a crowd. If you're pushed against them, ____   a result, you may be hurt badly.

 We should learn to ____  ourselves. Stay away from the crowd.

Remember: Whatever you do, safety is first!