问题 问答题 简答题

什么是细胞质遗传,它有哪些特点?

答案

参考答案:

细胞质遗传指由细胞质内的遗传物质即细胞质基因所决定的遗传现象和规律,又称非染色体遗传、非孟德尔遗传、染色体外遗传、核外遗传、母体遗传。 

细胞质遗传的特点:

⑴遗传方式是非孟德尔式的;杂交后一般不表现一定比例的分离。

⑵正交和反交的遗传表现不同;F1通常只表现母体的性状,故又称母性遗传。

⑶通过连续回交能将母本的核基因几乎全部置换掉,但母本的细胞质基因及其所控制的性状仍不消失。

⑷由附加体或共生体决定的性状,其表现往往类似病毒的转导或感染。

阅读理解

根据短文内容,判断正(T)误(F)。

     We often see people in different offices wear different clothes. In America, a businessman goes to 

work in a dark suit, with black shoes, socks and a tie. A reporter goes to work in old blue jeans, a work

 shirt and sneakers (运动鞋). These two kinds of clothes are suitable for their work. 

     If you are a college student who will leave school soon, before starting a job, you have to buy some 

new clothes. And you'd better have a look at "what everyone else is wearing" in the office. On certain

(某种) kinds of business occasions, the men wear only suits with white shirts and dark ties. On others, 

men can wear jackets.

      Dressing is very important. Without it, there is no successful fashion. It would be helpful if everyone 

looks at himself in the mirror before leaving home every morning. 

( )1. It's very common to see people in different offices wear the same clothes.                                  

( )2. If you are a student, you'd better know "what everyone else is wearing" in an office before  

            working there.

( )3. Suits with white shirts and dark ties are for men on certain kinds of business occasions.

( )4. A reporter often goes to work in a dark suit.                                                                

( )5. Dressing is important for successful fashion.                                                                

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