问题 单项选择题

下列有关植物激素调节的叙述,正确的是( )。
①可利用适宜浓度的赤霉素促进细胞伸长,使植物增高
②在植物组织培养中生长素和细胞分裂素的不同配比会影响组织分化
③使同种植物的扦插枝条产生相同生根效果的2,4—D浓度相同
④在太空失重状态下植物激素不能进行极性运输,根失去了向地生长的特性

A.①②
B.③④
C.①③
D.②④

答案

参考答案:A

解析: 由赤霉素功能易知①正确;在植物组织培养中,生长素用量与细胞分裂素用量比值高时,有利于根的形成,抑制芽的形成;反之则有利于芽的分化而抑制根的形成,故②正确;同种植物的不同组织以及同种组织的不同发育时期对生长素的敏感性不同,③错误;极性运输与地心引力无关,④错误。

单项选择题
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Beginning college is exciting: new ideas to explore, new challenges to be met and many decisions to be made; your future begins here.

However, you will find college life is different from your previous school environment. Many of us can be easily overwhelmed by the details of running a well-balanced life. While some of us may have the know-how, I guess there are more of us who can benefit from learning about the experiences of others who have walked the college halls before you.

The following you may find of use about life on campus:

·Plan well. There are so many new things to do at a new college or university. Give yourself time to make new friends and became familiar with the campus, but don’t forget why you are there. Give some time for social activities and manage your time wisely.

·If you don’t have a “system” for planning your time now (like a day timer a computer data book). get one. Most of all, don’t depend on your memory.

·Don’t miss the guidelines. The restrictions, rules and regulations of all kinds can usually be found in your student’s handbook. Consider them well-balanced food for thought. What dates are important? What pieces of paper need to be handed in? What can / can’t you do in your student residence(住处)? Who has the right for what? What do you need to complete to graduate?

·Write the word “STUDY” on the walls of our bedroom and bathroom, and maybe it will help to to write it on a piece of paper and stick it on the telephone, TV and the kitchen table. Consider this — you are paying thousands of dollars for your course. You pay every time you have to repeat or replace a course.

·Build your identity. This is the time for you to decide what to do and what not to do. Take as much time as you need to explore new ideas. Do not be afraid of the beyond. This is learning to make good choices.

小题1:What is the main purpose of the passage?

A.To offer advice on college life.

B.To explain why college life is exciting.

C.To describe the importance of college life.

D.To persuade you to go to college.小题2:According to the passage, why is it exciting to begin college life?

A.Because you will have more freedom at college.

B.Because you will no longer be afraid of the beyond

C.Because you prepare for your future career and life there.

D.Because professors there will provide you with many new ideas.小题3:The underlined word “know-how” refers to _____

A.An understanding of how things are going at college

B.Practical knowledge about how to behave and what to do at college

C.College halls where rules and regulations are presented

D.An environment completely different from the one you’re used to小题4:According to the passage, college students _______.

A.needn’t learn from those who went to college before them

B.spend as much time as possible on social activities

C.should know what they have fight for on campus

D.are supposed to repeat or replace at least one course