下列关于DNA的粗提取实验和血红蛋白的提取实验,叙述正确的是[ ] A.前者选择

题型:选择题

问题:

下列关于DNA的粗提取实验和血红蛋白的提取实验,叙述正确的是[ ]

A.前者选择鸡血细胞作材料较好,后者选择哺乳动物成熟的红细胞作实验材料较好

B.样品预处理时,前者静置1天处理除去上清液即可,后者要加入清水反复低速短时间离心洗涤,至上清液无黄色为即可

C.DNA粗提取实验中,往2mol/L氯化钠溶液中加入蒸馏水析出DNA时,应缓慢加入,直到出现黏稠物为止

D.血红蛋白的提取和分离实验的原理是在电场中带电颗粒迁移的速度不同

考点:DNA的粗提取与鉴定血红蛋白的提取和分离
题型:选择题

投资组合理论认为,对于相同的宏观经济环境变化,不同投资项目的收益会有不同的反应。()

题型:选择题
Three small fish lived in the sea. When they were very young, their parents died. They had to  15  each other day after day. Finally, they grew up and   16  to swim deeper and further.
One morning, the three fish were   17  to a shallow(浅) water by a big wave(浪). A small boat was taken there, too. It was hard for the fish to go back to the sea because the boat was right in front of them. The largest fish realized that they were   18  , and said they had to find a way to leave there as fast as possible. The second largest fish   19  with his elder brother, but the youngest one did not. He said that there was much   20  for their activities, so he would not worry at all and still swam around   21 .
At last, the largest fish returned to the   22  by jumping over the lowest part of the boat. The second largest fish also succeeded in   23   his elder brother in the other side of water. But the youngest one didn’t follow them and still swam joyfully.
Two hours later, when the sun rose up, the water in the small shallow corner   24 . The fish who did not try to return to the sea died of lack(缺乏) of water.
小题1:
A.listen to B.look afterC.talk withD.worry about
小题2:
A.daredB.hatedC.refusedD.stopped
小题3:
A.allowedB.givenC.invitedD.taken
小题4:
A.in safetyB.in doubtC.in dangerD.in peace
小题5:
A.agreedB.talkedC.disagreedD.discussed
小题6:
A.timeB.foodC.waterD.air
小题7:
A.slowlyB.sadly C.luckilyD.happily
小题8:
A.seaB.riverC.lakeD.pool
小题9:
A.catchingB.joiningC.takingD.telling
小题10:
A.rose up B.ran outC.washed awayD.dried up
题型:选择题

常引起副肿瘤综合征的肺癌是()

A.腺癌

B.鳞状细胞癌

C.大细胞癌

D.小细胞癌

E.肉瘤样癌

题型:选择题

()的召开以及()的成立,标志着中国社会学恢复与重建工作的开始。

题型:选择题

下列有关生物多样性的叙述,正确的是()

A.四川地震灾区的部分大熊猫转移到成都、北京等地饲养属于就地保护

B.森林能调节气候属于生物多样性的直接价值

C.保护生物的多样性就是保护濒危生物

D.保护生物多样性的最有效措施是建立自然保护区

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