问题 解答题

小明的爸爸和妈妈都是有耳垂的,而小明自己却是无耳垂,小明的姐姐有耳垂,如图所示.请你帮小明分析一下:

(1)显性性状是______.

(2)若显性基因用D表示,隐性基因用d表示,则小明父母的基因组成分别是______和______.

(3)小明姐姐的基因组成可能是______.

答案

(1)由显性基因控制的性状是显性性状,由隐性基因控制的性状是隐性性状;在耳垂的有无这对相对性状的遗传中,小明出现了他的父母没有的性状,说明无耳垂是隐性性状,由隐性基因控制,那么有耳垂为显性性状,由显性基因控制.

(2)若用D表示显性基因,d表示隐性基因,则这对基因的遗传图解如图所示:则无耳垂的小明的基因组成是dd,其父母的基因组成是Dd.

(3)小明的姐姐有耳垂,因此小明姐姐的基因组成可能是DD、Dd.

故答案为:

(1)有耳垂   (2)Dd 和 Dd   (3)DD或Dd

阅读理解

“Cool” is a word with many meanings. Its old meaning is used to express (表示) a temperature that is a little bit cold. As the world has changed, the word has had many different meanings. “Cool” can be used to express feelings of interest in almost everything.

When you see a famous car in the street, maybe you will say. “It’s cool.” You may think “He’s so cool,”when you see your favorite football player.

We all maximize(扩大)the meaning of “cool”. You can use it instead of many words, such as “new” or “surprising”. Here’s an interesting story we can use to show the way the word is used. A teacher asked her student to write about the waterfall(瀑布) they had visited. On the student’s paper was just the one sentence, “It’s so cool.”Maybe he thought it was the best way to show what he saw and felt.

But the story also shows a scarcity(缺乏)of words. Without “cool”, some people have no words to show the same meaning. So it is quite important to keep some credibility(可信性).Can you think of many other words that make your life as colorful as the word “cool”? I can. And I think they are also very cool.

小题1:In the passage, the word “express” means “_______”.

A.see

B.show

C.know

D.feel小题2:If you are ________ something, you may say,“It’s cool.”

A.interested in

B.angry about

C.worried about

D.unhappy with小题3:The writer takes an example to show he is ________ the way the word is used.

A.pleased with

B.strange to

C.worried about

D.unhappy with小题4:In the passage, the writer suggests(暗示)that the word “cool”___________.

A.can be used instead of many words

B.usually means something interesting

C.can make your life colorful

D.may not be as cool as it seems

填空题