Question

Bacterial Quorum Sensing

Bacteria(细菌)play an important role in our lives. They can keep us alive as well as make us sick. It wasn’t until fairly recently that we learned bacteria can communicate with one another.

In the 1960s, researchers found that a kind of bacteria called Vibrio fischeri（费氏弧菌） produced no light when they were alone, but that they exhibited great amount of light as the bacterial population grew to a certain number. How did this happen? How can Vibrio fischeri tell the difference between times when they’re alone and times when they’re in a community, and then all do something together?

Researchers found they talk to each other with a chemical language—signal molecules(信号分子). Vibrio fischeri makes signal molecules, and it also has a receptor on its surface that fits like a lock and key with a signal molecule. As the bacteria increase, more and more signal molecules are sent into the environment. When signal molecules increase to a certain amount, they lock down into those receptors and information comes into the bacteria, which tells them how many neighbors there are. As soon as they realize the population has hit the certain number, all of the bacteria behave as a group, making light together. In the past ten years, researchers have found all bacteria have systems like this: they make and recognize chemical words, determine(判断)the size of the community, and carry out tasks that would be unsuccessful if a single one were to act alone. This process is called quorum sensing.

Most of the time, bacteria live with thousands of other species (种类)of bacteria. There has to be a language of interspecies communication. In fact, bacteria have another kind of signal molecule, which is the common language used by all species. Moreover, this kind of molecule has its own receptor. In this way, bacteria are able to count different populations, and then they decide what task to carry out depending on which species has the greatest population.

Knowing how bacteria communicate could influence how we fight disease. What if bacteria can’t talk or hear? They won’t recognize when there are enough bacteria and when to exhibit the group behavior to make us sick. Researchers are developing a method—to make molecules that look like the real ones and then they lock into the receptors to jam recognition of the real situation.

On the other hand, researchers also improve the conversation of the beneficial bacteria, so they can do things that we want them to do better than they would do on their own.

1.According to the passage, what can we learn about quorum sensing?

A.Quorum sensing may happen when there is only one Vibrio fischeri.

B.Signal molecules are kept away from receptors during quorum sensing.

C.Most bacteria have similar systems to make light during quorum sensing.

D.Bacteria carry out a group task when their population hit a certain number.

2.What can we learn from the passage?

A.The more species there are, the more group actions bacteria will take.

B.In different environments, bacteria have different interspecies languages.

C.Beneficial bacteria communicate better by themselves than harmful ones.

D.To fight disease, researchers try to turn off the communication between harmful bacteria.

3.The passage is mainly about ________.

A.why bacterial population grows B.how bacteria communicate with each other

C.which bacteria help fight disease D.what scientists do to find quorum sensing

Answer

1.D

2.D

3.B

【解析】

本文向我们介绍了细菌群体感应机制，告诉我们细菌是如何相互交流的。

1.

细节理解题。根据第二段中“As soon as they realize the population has hit the certain number, all of the bacteria behave as a group…if a single one were to act alone. This process is called quorum sensing.”可知，一旦发现细菌数量达到一定数量，所有的细菌就会一起发光。研究人员发现所有的细菌都有这样的系统，判断群体的大小，并且如果单独行动的话执行的任务将会失败。这个过程称为群体感应。结合选项，故选D。

2.

推理判断题。根据第四段中“Researchers are developing a method—to make molecules that look like the real ones and then they lock into the receptors to jam recognition of the real situation.”可知，研究人员正在开发一种方法——使分子看起来像真实的分子，然后它们锁定在受体上，阻碍对真实情况的识别。所以为了对抗疾病，研究人员试图关闭有害细菌之间的交流。故选D。

3.

主旨大意题。A：细菌种群为什么会增长；B：细菌是如何相互交流的；C：哪些细菌有助于对抗疾病；D：科学家如何发现群体感应。分析全文内容可知，本文向我们介绍了细菌群体感应机制，告诉我们细菌是如何相互交流的。故选B。