问题 问答题 简答题

简述卵细胞的发育和成熟过程

答案

参考答案:

①卵原细胞的增殖期:

核大,质少,通常有1-2个核仁。通过有丝分裂的形式增加数量,进入卵母细胞生长期

②卵母细胞生长期:

1、小生长期(第Ⅰ和第Ⅱ时相卵母细胞):细胞质的增长,核仁数量增多,具有一层滤泡膜。

2、大生长期(第Ⅲ时相和第Ⅳ时相卵母细胞):早期,滤泡膜增加至二层,出现脂肪泡和液泡(皮质泡)。中期,滤泡膜变为多层,脂肪泡增加,液泡增大,出现了卵黄颗粒。晚期,卵黄颗粒不断积累,脂肪泡继续合并,液泡增大,其内涵物外倾

③成熟期:

核极化,核膜和核仁溶解,卵黄粒融化为胶状物

阅读理解

阅读理解

     The White family come to a new big city, but Mrs White's son, Bob, is not happy. He doesn't

have anyone to play with. "Don't worry!" says his mother. "You will soon make friends here."

     One morning, there is a knock at the door. Bob's mother, Mrs White, opens it. There stands

a woman with brown hair. It is Mrs Miller. She comes to borrow two eggs. She wants to make

cakes. Mrs White gives her two. In the afternoon there is another knock at the door. Mrs White

opens it and she sees a boy standing there. "My name is Jack Miller," he says. "My mother sends

you this cake and the two eggs."

     "Well, thank you , Jack," says Mrs White. "Come in and meet my son Bob."

     Look! Bob and Jack are having cake and milk. They are playing football. Now they are friends!

Jack says, "I'm glad you live next door." Bob says, "I must thank your mother for coming to borrow

eggs." Jack laughs and tells Bob, "My mother doesn't want the two eggs, but she wants to make

friends with your mother. " Bob says, "That's a funny way to make friends. It's an easy way, too.

It can work!

1. Bob feels __________ when his family moves to a new city.

A. unhappy

B. happy

C. tired

D. busy

2. Mrs Miller __________ one morning.

A. gives Mrs White a piece of cake

B. asks Bob to play with his son

C. borrows eggs from Mrs White

D. lends two eggs to Mrs White

3. In the afternoon __________ have cake and milk together.

A. Jack and Mrs Miller

B. Bob and his mother

C. Mrs White and Mrs. Miller

D. Bob and Jack

4. Which of the following is true?

A. Mrs Miller is Mrs White's old neighbor(邻居).

B. Mrs Miller wants to make friends with the Whites.

C. There aren't any eggs in Mrs White's home one morning.

D. There aren't any eggs in Mrs Miller's home.

5. The best title of this passage is __________.

A. Way to Borrow Eggs

B. Way to Make Cakes

C. Way to Make Friends

D. How to Make Cakes

选择题