题干

下列与实验相关的叙述,错误的是(  )

A:马铃薯块茎捣碎后的提取液可检测出蛋白质

B:光学显微镜,可用于观察植物细胞的质壁分离现象

C:检测酵母菌培养过程中是否产生CO2,可判断其呼吸方式

D:在95%乙醇中加入无水Na2CO3后可提高色素的溶解度

上一题 下一题 0.0难度 选择题 更新时间:2017-01-07 09:58:46

答案(点此获取答案解析)

C

同类题2

What do you do if you're stranded(处于困境的)on a lonely island? Surely you need to find a way to get in touch with the outside world. Your best chance of doing this is to draw the attention of a passing plane.
  Body signals(信号)
  Pilots from different countries understand body signals if they have the correct training. When you wave your arms up and down in a straight line, it means "yes". When you point downwards and swing your arm from side to side, it means "no". If you want the pilot to know that it's safe to land, push your hands out in front of you and bend(弯曲)your knees. If you want to say that it's not safe to land, put your arms in the air and move them to one side.
  Smoke signals
  The smoke from a fire can be seen from far away, so it's a good way to draw attention. If the weather is dry, it isn't hard to start a fire. Remember, however, that fires can be very dangerous if they get out of control. Never light a fire unless you're sure that it can't spread. If the ground is dark, light smoke can be seen more easily. Green grass and leaves produce light smoke.
  Ground-to-air signals
  It's a good idea to build some signals, too. Use large pieces of wood to make the symbols(标记). If you can't find any wood, use earth. Some useful symbols are:
  F "I need food and water."
  II "I need medicine."
  I "I am badly hurt."
  X" I am unable to move from here."
  Pilots' replies
  If the pilot lowers the plane's wings from side to side, this means "message received and understood". (At night, the pilot flashes the plane's green lights.) If the pilots flies the plane in a clockwise circle, this means "message received but not understood".(At night, the pilot flashes the plane's red lights.)
However, there is no signal which means "message not received". Why not?