问题 填空题

(1)填写图中各部分的名称:

②______ ③______④______ ⑥______ ⑧______ ⑨______

(2)⑥外面是______,里面是______,⑥将来发育______.

(3)桃花等被子植物特有的受精方式为______.

答案

一朵花是有花托、萼片、花瓣、雌蕊和雄蕊等组成,雌蕊有柱头、花柱、子房三部分组成,雄蕊有花药和花丝两部分组成.受精后子房壁发育成果皮,胚珠发育成种子,种子和果皮构成果实.当花粉落到雌蕊的柱头上后,在柱头黏液的刺激下,花粉萌发出花粉管,花粉管穿过花柱到达子房胚珠珠孔后,前端破裂释放出两个精子,其中一个精子与珠孔附近的卵细胞融合,形成受精卵.另一个精子与中央极核融合形成受精极核.这个过程称为双受精.双受精现象是被子植物特有的受精方式. 
故答案为:
(1)②柱头; ③花药; ④花柱;   ⑥子房;⑧雌蕊; ⑨雄蕊  
(2)子房壁;胚珠;果实
(3)双受精

单项选择题 A2型题
阅读理解

阅读理解。

     As any homemaker who has tried to keep order at the dinner table knows, there is far more to a family meal

than food. Sociologist Michael Lewis has been studying 50 families to find out just how much more.

     Lewis and his co-workers carried out their study by videotaping (录像) the families while they ate ordinary

meals in their own homes. They found that parents with small families talk actively with each other and their

children. But as the number of children gets larger, conversation gives way to the parents'efforts to control the

loud noise they make. That can have an important effect on the children. "In general the more question-asking

the parents do, the higher the children's IQ scores," Lewis says. "And the more children there are, the less

question-asking there is." The study also provides an explanation for why middle children often seem to have a

harder time in life than their siblings (兄弟姐妹). Lewis found that in families with three or four children, dinner conversation is likely to center on the oldest child, who has the most to talk about, and the youngest, who needs the most attention. "Middle children are invisible," says Lewis. "When you see someone get up from the table and walk around during dinner, chances are it's the middle child." There is, however, one thing that stops all

conversation and prevents anyone from having attention: "When the TV is on," Lewis says,"dinner is a

non-event."

1. The writer's purpose in writing the text is to ______.

A. show the relationship between parents and children

B. teach parents ways to keep order at the dinner table

C. report on the findings of a study

D. give information about family problems

2. Parents with large families ask fewer questions at dinner because _______.

A. they are busy serving food to their children

B. they are busy keeping order at the dinner table

C. they have to pay more attention to younger children

D. they are tired out having prepared food for the whole family

3. By saying "Middle children are invisible" in paragraph 3, Lewis means that middle children ______.

A. have to help their parents to serve dinner

B. get the least attention from the family

C. are often kept away from the dinner table

D. find it hard to keep up with other children

4. Lewis' research provides an answer to the question ______.

A. why TV is important in family life

B. why parents should keep good order

C. why children in small families seem to be quieter

D. why middle children seem to have more difficulties in life

5. Which of the following statements would the writer agree to?

A. It is important to have the right food for children.

B. It is a good idea to have the TV on during dinner.

C. Parents should talk to each of their children frequently.

D. Elder children should help the younger ones at dinner