问题 单项选择题 A1/A2型题

关于非竞争性抑制作用哪项正确?()

A.Km↓、Vmax

B.抑制剂的结构与底物相似

C.Km↓、Vmax不变

D.抑制剂和底物结合在酶分子的不同部位

E.Km不变、Vmax增大

答案

参考答案:D

解析:非竞争性抑制剂与底物的结构无相似性,结合在酶活性中心以外的部位。此类抑制Km不变、Vmax减小。

阅读理解

阅读理解。

      There are four seasons in a year in China. Spring comes in February. May, June and July make the

summer season. August, September and October make the autumn season. November, December and

January make the winter season. In different seasons people wear different clothes and do different things.

For example, the weather is hot, so people usually wear cool clothes and do things like swimming, boating

or surfing.

      Near the North Pole there are only two seasons. They are winter and summer. In winter, nights are

long. For more than two months you can't see the sun, even at noon. In summer, the days are long. For

more than two months the sun never goes down and there is no night.

     The people living near the North Pole are called Inuit. In summer they live in tents and catch deers for

food. In winter they live in small round snow houses. They can build a snow house in two hours. They

travel around by using dogs to carry their things. They make holes in the ice and catch fish and seals.

They eat much meat but not many vegetables.

1. The two seasons near the North Pole are _____. [ ]

A. spring and autumn

B. summer and winter

C. rainy season and dry season

D. spring and winter

2. You can't see the sun for _____ in North pole in a year.[ ]

A. a season

B. half a year

C. more than two months

D. half a year

3. Autumn in China _____. [ ]

A. is cold

B. lasts from August to October

C. hot

D. come after spring

4. Near the North Pole _____ in summer. [ ]

A. the days aren't long

B. the nights are long

C. there's no night for more than two months

D. 24 hour days last two months 

5. The people in the North Pole eat much _____. [ ]

A. vegetables

B. meat

C. milk

D. bread

单项选择题 A1型题