题干

在农业生产研究上,常常需要进行微生物的培养和计数.

(1)如图是利用____ 法进行微生物接种,把聚集的菌种逐步____ 分散到培养基的表面.

(2)分析下面培养基的配方:NaNO3、KH2PO4、NaH2PO4、MgSO4•7H2O、KCl、H2O.若此培养基用于培养分解尿素的细菌,则应除去上述____ 成分,并加入____ ,以补充____ 源.

(3)三位同学用稀释涂布平板法测定同一土壤样品中细菌数量.在对应稀释倍数为106培养基中,得到以下统计结果:甲同学涂布了两个平板,统计的菌落数是236和260,平均值248;乙同学涂布了三个平板,统计的菌落数是210、240和250,取平均值233丙同学涂布了三个平板,统计的菌落数是21、212和256,取平均值163;在三位同学统计中,只有一位同学的统计是正确的,指出另两位同学的统计为什么不正确____ .

(4)若在稀释倍数为106的培养基中测得平板上菌落数的平均值为233,那么每毫升样中的菌落数是(涂布平板时所用稀释液的体积为0.2mL)____ 

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答案(点此获取答案解析)

\u5e73\u677f\u5212\u7ebf\u3000,\u7a00\u91ca,NaNO3\u3000,\u5c3f\u7d20\u548c\u8461\u8404\u7cd6,\u6c2e\u3001\u78b3,\u7532\u540c\u5b66\u53ea\u6d82\u5e03\u4e86\u4e24\u4e2a\u5e73\u677f\uff0c\u5b9e\u9a8c\u6570\u636e\u8bf4\u670d\u529b\u4e0

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    Many people traveled to Las Vegas, Nevada last week for the 50th Consumer Electronics Show, or CES. The show is said to have the largest collection of new electronic devices in the world.

    The show had many examples of “smart home” devices. “Smart home” technology is designed to make life easier for people by letting computers control many things inside our homes. One such device actually begins working outside the home, when someone arrives and rings the doorbell.

    “When someone comes to your front door and rings the doorbell, the light can turn on immediately. I get a notification when I'm halfway around the world that someone came, and I can start talking to the person who's at my front door, and I can say, 'Oh, here let me let you in,' I can unlock the door for them very easily.” Said Vivint, a smart home service provider.

    One electronics maker launched a device that lets people see and interact with their animals when they are away. The device, from Petcube, lets you remotely watch and talk to your pet through a personal device, according to a company official. It can even give the pet a treat—if you approve and order it.

    For heating or cooling, there is a smart thermostat. This device can also send you a message if a big storm causes leaks of flooding. “We're trying to catch it with just a few drips before it becomes a real big problem,” said Mike Sale of iDevices.

    A concern for many homeowners is the possibility that someone else might find a way to attack these smart home devices. An official from Vivint said his company is sure that only owners of the home can gain use of information on the devices. Warren Katz from iDevices said his company employs engineers from the defense industry to help prevent hacking.