问题 单项选择题

下列关于变构酶的叙述,错误的是

A.变构酶催化非平衡反应

B.多为代谢途径的关键酶

C.属于慢速调节

D.不一定都具有催化亚基和调节亚基

E.酶构象变化后活性可升高或降低

答案

参考答案:C

解析:变构酶:①催化非平衡反应;②多为代谢途径的关键酶;③与变构效应剂呈可逆结合;④不一定都具有催化亚基和调节亚基;⑤酶构象变化后活性可升高或降低,属于快速调节。

单项选择题
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Mark Twain was a great writer. He was from the USA. He was born in 1835. He was also a famous speaker. He was famous for his sense of humour. Many people liked to listen to him talk because he liked to tell some interesting stories to make people laugh all the time.   One day Mark Twain was going to a small town because of his writing. Before he was going to leave, one of his friends said to him that there were always a lot of mosquitoes in the town and told him that he’d better not go there. Mark Twain waved (摇动) his hand and said, “It doesn’t matter. The mosquitoes are no relatives of mine. I don’t think they will come to visit me.”

After he arrived at the town, Mark Twain stayed in a small hotel near the station. He went into his room, but when he was just about to have a rest, quite a few mosquitoes flew about him. The waiters felt very sorry about that. “I’m very sorry, Mr Mark Twain. There are too many mosquitoes in our town.” One of them said to him.

Mark Twain, however, made a joke, saying to the waiter, “The mosquitoes are very clever. They know my room number. They didn’t come into the wrong room.” What he said made all the people present laugh heartily.

But that night Mark Twain slept well. Do you know why? That was because all the waiters in the hotel were driving the mosquitoes away for him during the whole night.

65. That day Mark Twain went to the town _____.

A. to see one of his friends

B. because he wanted to do something there for his writing

C. because he was told there were a lot of mosquitoes there

D. to see one of his relatives

66. The waiters felt sorry because _____.

A. they did something wrong to Mark Twain   

B. their hotel was too small

C. the room was not very clean  

D. there were quite a few mosquitoes in Mark Twain’s room

67. All the people present laughed heartily because _____.

A. the mosquitoes were very clever and they didn’t come into the wrong room

B. the mosquitoes knew Mark Twain’s room number

C. Mark Twain gave the waiters some nice presents  

D. Mark Twain made a joke

68. From the story we know _____.

A. no mosquitoes troubled Mark Twain in the night

B. the owner of the hotel told the waiters to look after Mark Twain well at night

C. Mark Twain didn’t have a good rest that night

D. there were not mosquitoes in the hotel any longer